Waterborne Pathogens: Detection and Treatment [1 ed.] 0128187832, 9780128187838

Table of contents :
Cover
Waterborne Pathogens: Detection and Treatment
Copyright
Contributors
About the editors
Professional experience
Academic honors
Visiting assignments in various universities—widely traveled
Preface
Acknowledgments
1 - Emerging waterborne pathogens in the context of climate change: Vibrio cholerae as a case study
1. Introduction
2. Vibrio cholerae and its environmental reservoir
3. Attachment
4. Viability of the bacterium through the interepidemic period
5. Cyanobacterial reservoir and the seasonality of cholera: the Bangladesh model
6. Transmission of cholera during epidemics
7. Impact of climate on cholera
8. Conclusion
References
2 - Ubiquitous waterborne pathogens
1. Introduction
2. Waterborne pathogens
2.1 Waterborne bacteria
2.1.1 The genus Vibrio
2.1.2 The genus Salmonella
2.1.3 The genus Shigella
2.1.4 The genus Escherichia
2.1.5 The genus Burkholderia
2.1.6 The genus Campylobacter
2.1.7 The genus Francisella
2.1.8 The genus Legionella
2.1.9 Mycobacterium avium complex
2.2 Waterborne viruses
2.2.1 Adenoviruses
2.2.2 Astroviruses
2.2.3 Caliciviruses
2.2.4 Noroviruses
2.2.5 Sapoviruses
2.2.6 Enteroviruses
2.2.7 Hepatovirus A
2.2.8 Hepatovirus E
2.2.9 Rotaviruses
2.3 Waterborne protozoa
2.3.1 The genus Cryptosporidium
2.3.2 The genus Giardia
2.3.3 Entamoeba histolytica
2.4 Waterborne helminths
2.4.1 The genus Dracunculus
2.4.2 The genus Fasciola
3. Potential waterborne pathogens
3.1 Potential waterborne bacteria
3.1.1 Helicobacter pylori
3.1.2 Aeromonas hydrophila
3.1.3 The genus Leptospira
3.1.4 The genus Tsukamurella
3.1.5 The genus Bacillus
3.1.6 Cyanobacteria and cyanotoxins
3.2 Potential waterborne viruses
3.3 Potential waterborne protozoa
3.3.1 Microsporidia
3.3.2 Cystoisospora belli
3.3.3 Cyclospora cayetanensis
3.4 Potential waterborne helminths
3.4.1 The genus Schistosoma
4. Summary
Acknowledgment
References
3 - Waterborne pathogens: review of outbreaks in developing nations
1. Introduction
2. Waterborne pathogen outbreaks in developing countries
3. WASH and waterborne disease outbreaks
4. Water quality: contribution to disease
5. Groundwater quality
6. Intervention efforts
7. Conclusion
References
4 - Treatment of waterborne pathogens by reverse osmosis
1. Treatment of waterborne pathogens by reverse osmosis
1.1 Types of waterborne pathogens
1.2 Pathogen control in drinking water
1.3 Reverse osmosis
1.3.1 Basic terms and definition
1.3.1.1 Basic requirements for membrane materials
1.3.1.2 Pretreatment
1.3.1.3 Configuration of the reverse osmosis process
1.3.1.4 Membrane
1.3.1.5 Materials used for membrane
1.4 Removals of waterborne by reverse osmosis
2. Conclusion
References
5 - Treatment of waterborne pathogens by microfiltration
1. Treatment of waterborne pathogens by microfiltration
1.1 Overview of waterborne pathogens
1.2 Microfiltration versus conventional filtration
1.2.1 Advantages and disadvantages of conventional filtration for waterborne pathogens removal
1.3 Microfiltration
1.3.1 Mass transport in the microfiltration process
1.4 Waterborne pathogens removal by microfiltration
2. Summary and conclusions
References
6 - Filtration and chemical treatment of waterborne pathogens
1. Introduction
2. Waterborne pathogens and types of diseases
3. Source and transmission of waterborne pathogens
4. Filtration and chemical treatment
4.1 Filtration methods for treatment of pathogens
4.1.1 Household and small-scale water treatment
4.1.2 Drinking water treatment in plants/industries
4.1.3 Wastewater treatment in plant/industries
4.2 Chemical methods for treatment of pathogens
4.2.1 Chemical pretreatment
4.2.2 Chemical coagulation
4.2.3 Chemical disinfection
5. Conclusions and future scope
References
7 - Biofiltration technique for removal of waterborne pathogens
1. Introduction
2. Waterborne disease
2.1 Log removal
2.2 Turbidity
3. Biofiltration
3.1 Trickling filter
3.2 Slow sand filtration
3.3 Rapid sand filter
3.4 Stormwater biofilter
3.4.1 Submerged zone
3.4.2 Removal of pathogenic bacteria in stormwater biofilter
3.5 Biofilter design consideration for removal of microbial contaminants
3.5.1 Filter media
3.5.2 Amendments of filter media
3.5.3 Surface modification of filter media
3.5.4 Biofilm
3.5.5 Infauna
3.5.6 Vegetation
3.6 Microbial-earthworm ecofilters
4. Conclusion
References
8 - Thermal methods, ultraviolet radiation, and ultrasonic waves for the treatment of waterborne pathogens
1. Introduction
2. Thermal methods
3. The application of ultraviolet radiation
3.1 Basis of the process
3.2 The intensity of radiation and its dose
3.3 The required ultraviolet dose
3.4 Ultraviolet reactors
4. The application of solar disinfection
4.1 The basis of the process
4.2 Inactivation of microbes
4.3 The factors affecting the effectiveness of the process
4.4 Technological solutions
5. The application of ultrasonic waves
6. Summary
References
9 - Heat, solar pasteurization, and ultraviolet radiation treatment for removal of waterborne pathogens
1. Introduction
2. Heat treatment
2.1 Critical temperature and efficacy of boiling
2.2 Advantages and disadvantages
2.3 Combination with other techniques
3. Solar pasteurization
3.1 Batch system
3.2 Continuous flow-through system
4. Ultraviolet radiation
4.1 Electromagnetic spectrum of ultraviolet light and microbial inactivation
4.2 Ultraviolet disinfection instrument
4.2.1 Mercury-based ultraviolet lamps
4.2.2 Mercury-free ultraviolet lamps
4.3 Factors affecting ultraviolet disinfection
4.4 Advantages and disadvantages
5. Future scope
6. Conclusion
References
10 - Bioaugmentation for the treatment of waterborne pathogen contamination water
1. Introduction
2. Biological control of Legionella pneumophila—a most tracked waterborne pathogens in man-made water systems
2.1 Selection of anti-Legionella compounds producers
2.2 Biological molecules showing anti-Legionella activity
3. Antagonistic microbial strains as biological pesticides for lethal pathogenic microbes
3.1 Microbial consortium for optimum pollutant and pathogen removal
4. Bacteriophage for pathogen reduction in wastewater
4.1 Role of phage to control waterborne bacterial pathogens
4.2 Phage in wastewater treatment
5. Pathogen bacteria removal in constructed wetlands
5.1 Selection of antagonistic bacteria for removal of waterborne pathogens
6. Conclusion
References
Further reading
11 - Chemical treatment for removal of waterborne pathogens
1. Introduction
2. Regulated chemicals
3. Water treatment plants and its significance
3.1 The disinfection of drinking water
3.2 General overview of the water treatment
4. Raw water quality and disinfectant demand
5. Microbiological deliberation for disinfection and indicator organism
6. Conventional method of treatment
6.1 Physical and chemical treatments
6.2 Particulates aggregates and residuals
6.3 Chlorine
6.4 Effectiveness of chlorination on protozoa, bacteria, and virus and residues
6.5 Chloramine-based disinfection
6.6 Effectiveness and by-product of chloramine
6.7 Chlorine dioxide and effectiveness
6.8 Ozone
6.9 Ultraviolet disinfection
6.10 Human health and ecological effect
7. Conclusion
References
Further reading
12 - Molecular tools for the detection of waterborne pathogens
1. Introduction
2. Commonly encountered pathogens in water
2.1 Bacteria
2.2 Protozoa
2.3 Virus
3. Major types of detection platforms for the detection of waterborne pathogens
3.1 Luminescent molecular markers
3.2 Polymerase chain reaction–based molecular tools
3.3 Electrochemical sensors
3.4 Enzyme-linked immunosorbent assay
3.5 Magnetic biosensors
3.6 Designer “lab-on-a-chip” biosensor
3.7 Smartphone-based rapid monitoring system
4. Sensors and molecular tools in waterborne pathogens detection: where do we stand today?
4.1 Benefits
4.2 Limitations
4.3 Future prospects
5. Conclusion
References
Further reading
13 - Biosensors/molecular tools for detection of waterborne pathogens
1. Biosensors
1.1 Types of biosensors
1.1.1 Optical biosensors
1.1.1.1 Surface plasmon resonance biosensors
1.1.1.2 Evanescent field–based fiber optic biosensors
1.1.1.3 Fluorescence and chemiluminescence biosensors
1.1.1.4 Colorimetric biosensors
1.1.2 Piezoelectric biosensors (acoustic wave–based biosensors/mass sensitive detectors)
1.1.3 Electrochemical biosensors
2. Molecular methods
2.1 Different molecular methods of pathogen detection
2.1.1 Polymerase chain reaction and variants
2.1.1.1 Multiplex PCR and real-time PCR
2.1.2 Oligonucleotide DNA microarrays
2.1.3 Next-generation sequencing
2.1.4 Pyrosequencing
2.1.5 Fluorescence in situ hybridization
2.1.6 Immunology-based methods
3. Conclusion
References
14 - Drug and multidrug resistance in waterborne pathogens
1. Introduction
2. Bacteria with drug resistance and multiresistance represented in water environments
3. Drug resistance mechanism and genes involved in resistance and multiresistance
4. Factors driving of resistance
5. Tools for resistance and multiresistance determination
6. Emergence of bacteria resistant to antibiotics in aquatic environments
7. Summary and conclusions
Acknowledgment
References
Further reading
15 - Sorption as effective and economical method of waterborne pathogens removal
1. Sorption
1.1 Sorption process used in the waters treatment
1.2 Sorbents
1.3 Pathogens
References
16 - Methods used in situ for removal of waterborne pathogens
1. Introduction
2. Biological contaminants of water
3. Methods of removing waterborne pathogens
3.1 Self-purification processes in water
3.2 Biosurfactants
3.3 Photosensitizers
3.4 Filtration
4. Conclusion
Acknowledgment
References
17 - Effective control of waterborne pathogens by aquatic plants
1. Introduction
2. Removal of pathogens by aquatic plants
3. Role of wetlands in treating pathogen-contaminated wastewater
4. Conclusion and future studies
References
Further reading
18 - Nanoconjugates for detection of waterborne bacterial pathogens
1. Introduction
1.1 Indicators of microbial water quality
2. Major waterborne pathogens and their impact on humans
3. Waterborne bacterial pathogens
4. Conventional waterborne bacteria detection methodologies
5. Search for solution: nanoconjugates for detection of waterborne bacterial pathogens
5.1 Gold nanoparticles conjugated detection system
5.2 Colorimetric detection of active biomolecule–conjugated AuNPs
5.3 Silver nanoparticle conjugated detection system
5.4 Aptamers
5.5 Graphene oxide
5.6 Metal–organic frameworks
6. Conclusion: preparing for tomorrow, today
References
19 - Nanomaterials for removal of waterborne pathogens: opportunities and challenges
1. Introduction
2. Nanomaterials
2.1 Characteristics of nanoparticle
2.2 Types
2.2.1 Naturally occurring nanomaterials
2.2.2 Metals and their oxide-based nanomaterials
2.2.3 Carbon-based nanomaterials
2.2.4 Newly structured and engineered nanomaterials
2.3 Application in contaminated water treatment
3. Mechanism of cytotoxicity of nanomaterials
3.1 Naturally occurring nanomaterials
3.2 Metals and their oxide-based nanomaterials
3.3 Carbon-based nanomaterials
3.4 Newly structured and engineered nanomaterials
4. Applications of nanomaterials in waterborne pathogens treatment
4.1 Magnetic nanoparticles
4.2 Nanostructured membranes
4.3 Bioactive nanoparticles
4.4 Dendrimer-enhanced ultrafiltration
4.5 Photocatalytic inactivation by nanoparticles
4.6 Molecularly Imprinted Polymers
4.7 Bioinspired nanoparticles
4.8 Nanofibers
4.9 Nanosorbents
5. Limitations and upcoming challenges
5.1 Mode of application and side products of degradation
5.2 Nanotoxicity and its effects
5.3 Plausible solutions
6. Summary
Abbreviations
References
Further reading
20 - Applications of carbon nanotubes for controlling waterborne pathogens
1. Introduction
2. Antimicrobial activity of carbon nanotubes
2.1 Biocidal effect of native carbon nanotubes
2.1.1 Physiochemical property
2.1.2 External factors
2.2 Bactericidal effect of decorated carbon nanotubes
2.2.1 Metal nanoparticles
2.2.2 Antimicrobial agents
2.2.3 Polymers
3. Potential applications of carbon nanotubes for water disinfection
3.1 Immobilized carbon nanotubes
3.1.1 Membranes/filters
3.1.2 Adsorbents
3.2 Suspended carbon nanotubes
4. Limitations and possible risks of the use of carbon nanotubes for waterborne pathogen control
4.1 Toxicological and environmental concerns
4.2 Economic consideration
5. Conclusion
References
21 - Nanofiltration technology for removal of pathogens present in drinking water
1. Introduction
2. Waterborne diseases
3. Sources of pathogen contamination in drinking water
4. Currently available techniques for pathogen removal
5. Membrane-based technologies for pathogenic contaminant removal
5.1 Microfiltration
5.2 Ultrafiltration
5.3 Reverse osmosis
6. Nanofiltration technology for removal of pathogenic microbes
6.1 Mechanism of separation by nanofiltration membranes
6.2 Bacteria
6.3 Virus
6.4 Protozoa
7. Advantages of nanofiltration technology over other virus elimination processes
7.1 Specificity
7.2 Expectedness of virus removal
7.3 Process effectiveness and robustness
7.4 Process elasticity and easiness
7.5 Viral markers
7.6 Toxicological assessment
8. Future improvements in the technology
9. Conclusions
References
Further reading
Index
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Back Cover

Citation preview

Waterborne Pathogens Detection and Treatment

Edited by Majeti Narasimha Vara Prasad School of Life Sciences University of Hyderabad Hyderabad, India

Anna Grobelak Czestochowa University of Technology Faculty of Infrastructure and Environment Czestochowa, Poland

Butterworth-Heinemann is an imprint of Elsevier The Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, United Kingdom 50 Hampshire Street, 5th Floor, Cambridge, MA 02139, United States Copyright © 2020 Elsevier Ltd. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopying, recording, or any information storage and retrieval system, without permission in writing from the publisher. Details on how to seek permission, further information about the Publisher’s permissions policies and our arrangements with organizations such as the Copyright Clearance Center and the Copyright Licensing Agency, can be found at our website: www.elsevier.com/permissions. This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein). Notices Knowledge and best practice in this field are constantly changing. As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary. Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein. In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility. To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products, instructions, or ideas contained in the material herein. Library of Congress Cataloging-in-Publication Data A catalog record for this book is available from the Library of Congress British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library ISBN: 978-0-12-818783-8 For information on all Butterworth-Heinemann publications visit our website at https://www.elsevier.com/books-and-journals

Publisher: Matthew Deans Editorial Project Manager: John Leonard Production Project Manager: R. Vijay Bharath Cover Designer: Victoria Pearson Typeset by TNQ Technologies

Contributors Niyaz Ahmed, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh Shraddha Awasthi, Department of Applied Chemistry, Indian Institute of TechnologyBanaras Hindu University (IIT-BHU), Varanasi, Uttar Pradesh, India Rahul Bhadouria, Department of Botany, Delhi University, New Delhi, India Andrzej Butarewicz, Bia1ystok University of Technology, Department of Chemistry, Biology and Biotechnology, Bia1ystok, Poland Klaudia Ca1us, Czestochowa University of Technology, Faculty of Infrastructure and Environment, Department of Environmental Engineering, Czestochowa, Poland Sudip Choudhury, Centre for Soft Matter, Department of Chemistry, Assam University, Silchar, Assam, India John David Clemens, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh Bhupinder Dhir, School of Sciences, Indira Gandhi National Open University, Chennai, Tamil Nadu, India Anna Grobelak, Czestochowa University of Technology, Faculty of Infrastructure and Environment, Department of Environmental Engineering, Czestochowa, Poland Anup Kumar Gupta, Indian Institute of Technology (Indian School of Mines) Dhanbad, Dhanbad, Jharkhand, India Md. Hassan-uz-Zaman, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh Natasha Agustin Ikhsan, Department of Chemical Engineering, Institut Teknologi Bandung, Bandung, Jawa Barat, Indonesia Antonius Indarto, Department of Chemical Engineering, Institut Teknologi Bandung, Bandung, Jawa Barat, Indonesia Md. Sirajul Islam, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh Md. Shafiqul Islam, International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh Agata Jab1o
nska-Trypu
c, Bia1ystok University of Technology, Department of Chemistry, Biology and Biotechnology, Bia1ystok, Poland Ajay Kumar, Agriculture Research Organization, Volcani Centre, Derech HaMaccabim 68, Rishon LeTsiyon, Israel xv

xvi Contributors Sushil Kumar, Delhi College of Arts and Commerce, University of Delhi, New Delhi, India Iwona Kupich, Czestochowa University of Technology, Institute of Environmental Engineering, Czestochowa, Poland Anna Kwarciak-Kozlowska, Czestochowa University of Technology, Faculty of Infrastructure and Environment, Czestochowa, Poland Magdalena Made1a, Czestochowa University of Technology, Institute of Environmental Engineering, Czestochowa, Poland D.N. Magana-Arachchi, Molecular Microbiology & Human Diseases Unit, National Institute of Fundamental Studies, Kandy, Sri Lanka Anurag Maurya, Department of Botany, Shivaji College, University of Delhi, New Delhi, India Pradeep Kumar Mishra, Department of Chemical Engineering and Technology, Indian Institute of Technology-Banaras Hindu University (IIT-BHU), Varanasi, Uttar Pradesh, India Ankita Ojha, Maharaja College, VKSU, Arrah, Bihar, India Vivek Kumar Pandey, Department of Chemical Engineering and Technology, Indian Institute of Technology-Banaras Hindu University (IIT-BHU), Varanasi, Uttar Pradesh, India; Department of Food and Nutritional Sciences, University of Reading, Reading, United Kingdom Shilpi Pandey, Department of Botany, Centre of Advanced Study, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh, India Barbara Pieczykolan, Institute of Water and Wastewater Engineering, Faculty of Energy and Environmental Engineering, Silesian University of Technology, Gliwice, Poland Izabela P1onka, Institute of Water and Wastewater Engineering, Faculty of Energy and Environmental Engineering, Silesian University of Technology, Gliwice, Poland Sanchayita Rajkhowa, Department of Chemistry, Gauhati University, Guwahati, Assam, India Jyotirmoy Sarma, Department of Chemistry, Kaziranga University, Jorhat, Assam, India Manoj Kumar Singh, Department of Botany, Acharya Narendra Dev College, University of Delhi, New Delhi, India Rishikesh Singh, Institute of Environment and Sustainable Development, Banaras Hindu University, Varanasi, Uttar Pradesh, India Pardeep Singh, PGDAV College, Department of Environmental Sciences, Delhi University, New Delhi, India Vipin Kumar Singh, Department of Botany, Centre of Advanced Study, Institute of Science, Banaras Hindu University, Varanasi, Uttar Pradesh, India Monika Sobczyk, Czestochowa University of Technology, Faculty of Infrastructure and Environment, Department of Environmental Engineering, Czestochowa, Poland

Contributors xvii

Kumar Rohit Srivastava, Department of Chemical Engineering and Technology, Indian Institute of Technology-Banaras Hindu University (IIT-BHU), Varanasi, Uttar Pradesh, India Pradeep Kumar Srivastava, School of Biochemical Engineering, Indian Institute of Technology-Banaras Hindu University (IIT-BHU), Varanasi, Uttar Pradesh, India R.P. Wanigatunge, Department of Plant and Molecular Biology, University of Kelaniya, Kelaniya, Sri Lanka Indra Wibowo, School of Life Sciences & Technology, Institut Teknologi Bandung, Bandung, Jawa Barat, Indonesia Renata Wlodarczyk, Czestochowa University of Technology, Faculty of Infrastructure and Environment, Czestochowa, Poland El_zbieta Wo1ejko, Bia1ystok University of Technology, Department of Chemistry, Biology and Biotechnology, Bia1ystok, Poland Urszula Wydro, Bia1ystok University of Technology, Department of Chemistry, Biology and Biotechnology, Bia1ystok, Poland

About the editors Majeti Narasimha Vara Prasad is currently Emeritus Professor, School of Life Sciences, University of Hyderabad, Hyderabad, India. Formerly Dean, School of Life Sciences. Formerly Head, Department of Plant Sciences. Formerly Coordinator, Biotechnology Program. Formerly Coordinator of PG Diploma in Environmental education and management. He did his MSc (Botany) from Andhra University, Waltair, 1973e75, and PhD (Botany) from Lucknow University, Lucknow 1975e79 (research conducted at Birbal Sahni Institute of Palaeosciences, an autonomous institute under the Department of Science and Technology, Government of India).

Professional experience Lecturer, June 1980e85, Department of Botany, North Eastern Hill University, Shillong. University of Hyderabad, School of Life Science, Lecturer, 1985e86, Lecturer (Senior Scale) 1986e90; Reader, February 1990e98, and Professor since August 1, 1998 to May 10, 2018 in the Department of Plant Sciences. Dr. Prasad has made significant contributions to the field of plantemetal interactions, bioremediation, and bioeconomy. He has published 213 research articles in peer-reviewed journals, 135 book chapters, and 30 edited books by Elsevier, Academic Press, Fizmatlit Russia, John Wiley, Kluwer Academic, Ministry of Environment and Forests, Government of India, New Delhi, Marcel Dekker, Narosa, Russian Academy of Sciences, Springer, and Taylor & Francis. Citations of his publications as per google scholar are 16409, with an H-index of 63.

Academic honors 1. Recipient of Excellent Scholar Award by the XIX International Botanical Congress, July 23e29, 2017, Shenzhen, China xix

xx About the editors

2. Pitamber Pant National Environment Fellow 2007 awarded by the Ministry of Environment, Forests and Climate Change, Government of India 3. Recipient of Prof. KS Bilgrami memorial award, 2015, by the Society for Plant Research, India 4. Served as COST action 859 (Phytotechnologies) working group member, ESF 5. Elected FellowdLinnean Society of London, UK 6. Elected FellowdNational Institute of Ecology, New Delhi

Visiting assignments in various universitiesdwidely traveled l

l

l l l l l

l l l l l

NSERC foreign research awardee by the University Que’bec INRS-Eau, Canada, 1994 Department of Plant Physiology and Biochemistry, Jagiellonian University, Krakow, Poland, 1996 University of Coimbra, Portugal, 1999 Stockholm University, Institute of Botany, Sweden, 2000 University of Oulu, Oulu, by Finnish Academy Finland, 2002 University of South Australia, Adelaide, Australia, 2005 Al-Farabi Kazakh National University, Department of Botany, Almaty, Kazakhstan, 2006 Ural Federal University, Ekaterinburg, Russia, 2007e2015 Ghent University Faculty of Bioscience Engineering, Gent, Belgium, 2011 Mahasarakham University, Thailand, 2013e14 University of Santa Cruz, Ilhe’us-Bahia, Brazil, 2015 MHRD, Government of India secondment to Asian Institute of Technology Thailand for January to May semester 2017 visiting Professor, Thailand

Anna Grobelak is an Assistant Professor at Czestochowa University of Technology, Institute of Environmental Engineering. She completed her doctoral degree in 2012 in Environmental Engineering at Czestochowa University of Technology, Faculty of Infrastructure and Engineering. Her area of research is environmental engineering, biotechnology, and molecular toxicology. She has made a contribution to the field of waste water treatment, molecular diagnosis of pathogens, waste management, and bioremediation technologies (Google Scholar citations 746, h-index 13).

About the editors

xxi

She has published research articles in peer-reviewed journals and book chapters (in total 78). She is an author of patents, scientific opinions, and technological implementations for the industry. Much of her work has been conducted with participation in research projects and with industry concerning on waste and sewage sludge management, waste water systems, soil reclamation, and bioremediation.

Preface Over many years of science and technological development, it is general belief that we have already achieved so much progress to become master of the earth and the universe. However, this thought is illusory. Paradoxically, on the one hand, we are looking for traces of life in space while millions of people do not have access to clean drinking water. Safe drinking water production is an ancient art while establishing standards is relatively new. There are documented ways to improve water quality as early as 4000 BC. Alum was used for water treatment as early as 1500 BC and is still widely used. Water disinfection involves pathogen inactivation to control acute waterborne disease, balanced with the reduction of toxic disinfection by-products (DBPs). Although the last two decades experienced increased interdisciplinary collaborations among chemists, biologists, epidemiologists, engineers, and regulators, resolving the risks of DBPs follows a dated paradigm. A new integrated approach is required to determine the contaminants in source and drinking waters that increase health risks and to provide the foundation for novel disinfection practices for the 21st century. Chlorine is the most commonly used primary disinfectant in the world. Since its first usage as primary disinfectant in 1908, it has been used around the world in many forms to protect people against waterborne diseases such as diarrhea, cholera, Escherichia coli, Legionellosis, dysentery, etc. Chlorine reacts with organics in water and does produce some by-products, and unfortunately, these DBPs are carcinogenic in nature. This book is addressed to those of us who realize that the most basic important issue concerning human life is the access to clean drinking water. Water is the essence of life and becomes for many of us a treasure for which we must fight or pay a high price to make it usable. Progressive climate change, industrialization, and pressure from rich world economies on the intensive mining of valuable deposits cause the ever-increasing problem of pollution of the environment and waters and access to them. The different earth areas have slightly different technical problems in terms of water purification and residents’ access to clean drinking water. We come to writing when concluded that since the problem of water affects all the inhabitants of the globe, new solutions and technologies can be applied and can generate further improvements only if they are available to a wide audience from different countries and when they are

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xxiv Preface

represented by authors from different areas of the world. In this book we cover the issues and solutions of water treatment across worldwide. This book focuses on aspects of detection, identification, and removal methods of waterborne pathogens. This book copes both with theoretical and practical aspects and thus is especially dedicated to biologists, chemists, and environmental professionals. In this book, the worldwide authors described new threats of drinking water safety as well as new technologies of water treatment improving the currently used. In this book, the problem of water pathogens and water treatment is very holistic. Physical methods of water treatment such as filtration, radiation, heating, nanotubes, and nonporous materials were discussed, as well as chemical and biological methods. The book deals with current problems of pathogens in waters, including those pathogens that until now were considered to be nonexistent, even historical, but as it turns out, it is still a challenge for many societies. This book also addresses the issues of modern applications of scientific achievements such as biosensors or molecular tools in the detection of pathogens or monitoring the release of resistance genes into the environment. We recommend this book to microbiology and environmental engineering students and researchers as well as for potential stakeholders because this book provides current knowledge on drinking water pathogens highlighting the technical application of solutions. We hope that this book will be useful to advisers, extension officers, educators, and advanced researchers who are concerned about the protection of human health. We also hope that the efforts to forward the readers toward the better understanding of “Waterborne pathogens: detection and treatment” shall be fruitful.

Acknowledgments The editors would like to thank all the authors of this volume for their cogent and comprehensive contributions. The editors would also like to place on record their appreciation and thanks to Mathew Deans for his inspiration and vital thoughts regarding key inputs for the work. We thank Editorial Project Manager John Leonard for the excellent coordination of this fascinating project, suggestions, and help in many ways that resulted in timely publication. Thanks are also due to the Production Project Manager, Rajan, Vijay Bharath, and Cover Designer Victoria Pearson. Last but not least, we wish to thank numerous colleagues for sharing their knowledge, ideas and lending assistance, which helped to shape this book. Editors

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Chapter 1

Emerging waterborne pathogens in the context of climate change: Vibrio cholerae as a case study Md. Sirajul Islam, Md. Hassan-uz-Zaman, Md. Shafiqul Islam, John David Clemens, Niyaz Ahmed International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh

1. Introduction Emerging infectious diseases have become a major public health concern over the past decade, owing primarily to their unprecedentedly rapid spread. As a basic measure of this phenomenon, at least 50 emerging infectious agents have been identified over the past four decades (Dong et al., 2008). Considering that infectious agents are already present in the environment, the phenomenon of emergence or reemergence of a disease is the consequence of increased human exposure to the pathogen (Vouga and Greub, 2016). This significantly contributes to the concern surrounding emerging diseases, as increases in human exposure are factors of sociodemographic and environmental changes. With the rapid changes in lifestyle, global and regional conflicts, and the consequent population displacement events, there is a heightened risk of exposure to particular pathogens of previous unexposed groups. Perhaps even more fundamentally, the world is at the cusp of what has been declared the “biggest global health threat of the 21st century”danthropogenic climate change (Costello et al., 2009; Watts et al., 2018). Indeed, one of the major pathways of increasing human exposure to emerging pathogens is environmental change. The link between climate and the dynamics of disease spread has been demonstrated in the case of both waterborne and vector-borne diseases, particularly cholera, Escherichia coli diarrhea, malaria, dengue, and visceral leishmaniasis (Banu et al., 2014; Hossain et al., 2011; Reid et al., 2012). Notable targets of environmental change in terms of disease dynamics include, but are not limited to, host immunity, vector abundance, pathogen persistence Waterborne Pathogens. https://doi.org/10.1016/B978-0-12-818783-8.00001-3 Copyright © 2020 Elsevier Ltd. All rights reserved.

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2 Waterborne Pathogens

in the environment, and environmental contamination of water sources (Altizer et al., 2013; Metcalf et al., 2017). Furthermore, the effects of environmental change, particularly extreme weather events, can manifest indirectly in the form of population displacement and malnutrition. As such, the threat of emerging infectious diseases looms particularly large in the context of a changing climate. In this chapter, we will be discussing the emergence of waterborne pathogens driven by environmental change with Vibrio cholerae, the causative bacteria for cholera, serving as an elaborate case study. The rationale for choosing this organism as a model is twofold. First, cholera has been cited as a paradigmatic instance of the regulation of disease dynamics by means of environmental drivers (Colwell, 1996). The link between cholera incidence and a large number of environmental variables, ranging from sea surface temperature (SST) and sea surface height (SSH) and monsoon precipitation to large-scale events like the El NinoeSouthern Oscillation, has been reported in a number of studies (Emch et al., 2008; Baracchini, 2014; De Magny et al., 2008; Jutla et al., 2013). Secondly, cholera has been endemic in Bengal since ancient times, preceding the Indian campaign of Alexander the Great (Pollitzer, 1959; Glass and Black, 1992). It also happens to be the case that the Bengal Delta is ground zero for the worst impending effects of anthropogenic climate change. Termed one of the most climate vulnerable countries in the world and ranking sixth on the Global Climate Risk Index 1996e2015 (Huq, 2001; Kreft et al., 2013), the climate trends in Bangladesh over the previous decades, as well as those projected in the future, are significant causes for concern. Bangladesh has seen significant warming during 1970e2010, with a mean temperature increase much higher than the global average (Rahman and Lateh, 2016). Regional projections have variously predicted the increase in temperature to range from 1.5 to 4.8
C by 2050 (Gosling et al., 2011; Caesar et al., 2015; Nicholls et al., 2018). There is an anticipated 27 cm sea level rise in coastal Bangladesh within the same projection period (Dasgupta et al., 2014). Incidentally, the 12 critical climate vulnerabilities identified by the Government of Bangladesh include sea level rise and deeper penetration of saline water (Mamun et al., 2018), both of which are conducive to greater human exposure to V. cholerae. Indeed, researchers have implicated climate change as having played a key role in the emergence of the V. cholerae serotype O139 in Bangladesh (Vouga and Greub, 2016). Both the pathogen itself and its locus of endemicity, therefore, are optimally suited to a discussion of reemergence of waterborne pathogens driven by environmental change in the context of a shifting climate. In the remainder of this chapter, we will discuss the climate dependence of V. cholerae as a setting for understanding the pathway to, and consequence of, the environmentally mediated emergence of the pathogen. We will first outline the mechanism by which cholera outbreaks are seasonally regulated in Bangladesh via the growth and activity of its environmental reservoir. We will

Emerging waterborne pathogens in the context of climate Chapter | 1

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then discuss more recent studies which have made use of remote sensinge assisted data collection to understand the links between cholera incidence and macrolevel variables such as river discharge, SST, and SSHdall of which have been implicated as worsening because of climate change. We will then conclude by considering the possible consequences a changing climate would have in the emergence of this waterborne pathogen.

2. Vibrio cholerae and its environmental reservoir The climate dependence of V. cholerae is intrinsically tied to the identity of its environmental reservoir, as will be elucidated in later sections. Cholera maintains a regular (though not without exception) seasonal pattern in Bangladesh. The outbreaks of cholera reach their peak in the form of an epidemic during the premonsoon season of the year, with a second peak during the postmonsoon period (Emch et al., 2008; Jutla et al., 2013; Martin et al., 1969; McCormack et al., 1969; Merson et al., 1980; Glass et al., 1982; Samadi et al., 1983; Longini et al., 2002; Hashizume et al., 2010; Baracchini et al., 2017). During these epidemics, virulent forms of V. cholerae can be isolated both from the environment and from the patients (Khan et al., 1984). Once the epidemic subsides, however, the bacteria can no longer be isolated from the environment. The apparent disappearance of the bacteria during the interepidemic perioddmore specifically, the reservoir of its survival and persistence during this perioddhas been the subject of sustained scientific investigation since the discovery of the bacterium itself. A number of studies, based on both laboratory microcosms and the environment, have demonstrated that certain species of cyanobacteria act as the interepidemic reservoirs of V. cholerae in aquatic environments in Bangladesh. A terse digest of the findings of these studies is presented below.

3. Attachment Laboratory and field-based investigations demonstrate under fluorescent microscopy that the bacterium can bind with 3 of the 4 investigated phytoplankton (Tamplin et al., 1990), though it shows no similar attachment behavior with the 11 zooplankton species, including 5 copepods species. Further investigation suggests that V. cholerae prefers to attach to the cyanobacteria Anabaena sp. over other algal species such as Euglena spp. or Phacus spp. (Islam et al., 2015). The latter study also shows the bacterium associates with Anabaena sp. and a colonial cyanobacterium Microcystis aeruginosa (Fig. 1.1), but not with the more abundant Euglena spp. or Phacus spp. Unlike V. cholerae strains lacking mucinase (hap) gene, wild-type strains that contain the gene have been shown to be positively chemotactic toward cyanobacteria (Islam et al., 2002), which indicates that the specificity of the attachment mechanism might be mediated by mucin-dependent chemotaxis.

4 Waterborne Pathogens

FIGURE 1.1 (A) Association of Vibrio cholerae O1 with Anabaena variabilis in microcosm. (B) Association of V. cholerae O1 with Microcystis aeruginosa.

4. Viability of the bacterium through the interepidemic period The identification of the environmental reservoir of V. cholerae required the reevaluation of the bacterium detection methods as it has been shown that

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V. cholerae cannot be enumerated or isolated from the environment by conventional cultural methods when they exist in a stress-induced low-metabolic state dubbed as the “viable but nonculturable” (VBNC) state (Colwell and Huq, 1994; Islam et al., 1990, 1999). Researchers were successful in enumerating VBNC bacteria of different drinking water sources in a field study by using the fluorescent antibody (FA) technique (Brayton et al., 1987). This technique yielded higher counts of V. cholerae O1 than the most probable number indices technique, suggesting the probable wide prevalence of VBNC bacteria in cholera-endemic areas. The indirect FA technique, a variant of the FA technique, is widely used by researchers to enumerate bacteria in environmental and clinical samples (Islam et al., 1994a,c). There are also other example of studies including clinical (Sack and Barua, 1964) and environmental water samples (Colwell et al., 1985, 1990). The persistence of V. cholerae O1 in association with the cyanobacterium Anabaena variabilis in an artificial aquatic environment was studied by Islam et al. (1990). It was found in this study that even though the rate of survival of the culturable V. cholerae O1 in control water was 144 h, bacteria associated with A. variabilis could be isolated for only up to 120 h. Longer observation of the study samples revealed that the bacteria can enter the mucilaginous sheath of the algae and transform into VBNC form after 10 days. FA technique was useful in detecting the bacteria in algal sheath and was observed to retain this form for more than 15 months that is enough to cover the typical period of time between cholera epidemics. The bacteria can also retain their toxigenic properties during this period, which is an alarming public health concern (Islam, 1990). Phytoplankton samples were collected from ponds in Dhaka bimonthly for a year and were observed using fluorescent microscopy to detect the presence of VBNC V. cholerae (Islam et al., 1994b). In 16 samples out of the 24 samples collected, no culturable bacteria could be isolated but VBNC V. cholerae were found in the mucilaginous sheaths of A. variabilis. These two studies, if paired together, suggest that A. variabilis may be acting as an interepidemic reservoir of the cholera pathogen. A study recently conducted in Burkina Faso also reports that the biomass of phytoplankton positively correlates with the number of V. cholerae in environmental water reservoirs (Kabore´ et al., 2018). A more recent and comprehensive study involving microcosm-based laboratory experiment demonstrates that V. cholerae O1 in culturable form associated with A. variabilis can survive for 48 days, whether the nonculturable form can remain viable for over a year (Fig. 1.2) (Islam et al., 2015). The study also inspects the bimonthly water sample collection, this time from ponds in the rural area of Bangladesh. The study finds strong correlation of the VBNC bacterial count with A. variabilis level, as well as the local cholera cases. These studies serve as strong scientific evidence of the phytoplankton A. variabilis as the environmental reservoirs of V. cholerae O1 in Bangladesh.

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Log10 cells/ml or g

(A)

A. variabilis

0h

8h

24 h

2d

4d

6d

8d

12 d

Time (hour/day)

A. variabilis

(B) Log10 cells/ml or g

Algal water

Control water

9 8 7 6 5 4 3 2 1 0

Algal water

16 d

24 d

32 d

40 d

48 d

Control water

9 8 7 6 5 4 3 2 1 0 0h

8 h 24 h 2 d

4d

6d

8 d 12 d 16 d 24 d 32 d 40 d 48 d 56 d 64 d 176 d 365 d Time (hour/day)

FIGURE 1.2 (A) Survival of Vibrio cholerae O1 in various components of microcosms. (B) Detection of V. cholerae O1 in various components of microcosms by Direct Fluorescent Antibody (DFA) technique.

5. Cyanobacterial reservoir and the seasonality of cholera: the Bangladesh model Knowledge about the identity of the environmental reservoir of V. cholerae puts us in a position to determine the climate dependency of the disease seasonality with more clarity. Islam et al. first conceptualized a model of the seasonality of cholera in relation with the environmental reservoir of V. cholerae (Islam, 1987; Islam et al., 1994d), which was further strengthened by subsequent studies. In the following section, we will explore the various components of this model as well as the climate-cholera dynamics in the rural area context of Bangladesh. A research conducted in 2009 studying the correlation between climate variability and cholera prevalence (Islam et al., 2009) shows that the highest number of cholera incidents in a rural cholera-prone area in Bangladesh is in coincidence with elevated temperature (summer time) or lengthy sunshine with

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FIGURE 1.3 Three-dimensional surface plot of cholera cases/month for different levels of temperature (
C) and sunshine hours (h/day). Different levels of the total cholera incidents are indicated by different colors. The colors are distributed over the surface of temperature and sunshine hour levels. The bivariate frequency of interpolated sunshine hours and temperature is presented on the vertical axis. Temperature level 1 ¼ low (28.66
C). Sunshine hours level 1 ¼ low (6.82 h/day).

relatively lower temperature (winter time) hours throughout the year. The data are presented visually in Fig. 1.3, where it shows the monthly cholera occurrences plotted in a 3D surface plot over separate categorical temperature and sunshine hours. The explanation of this phenomenon could be that the synergistic effect of higher sunshine hours and temperature causes the elevation of cyanobacterial level in water as a result of the increased photosynthesis and concentration of nutrients due to lower water volume (Islam et al., 1994d). The growth of cyanobacteria in ponds increases with the decreased dissolved CO2 as a result of photosynthetic activity, which also ultimately leads to the increased dissolved oxygen level and pH of the water (Islam et al., 2015). This finding also supports the plausible explanation of the higher cyanobacteria levels in water. With increasing level of cyanobacteria in water, the bacterial load also increases, as they multiply within the algal sheaths (Islam et al., 1999, 2015). The general hypothesis is that the inception of a cholera epidemic corresponds with the breakdown of algal bloom due to decomposition (Islam et al., 1994d). A study on Vibrio parahaemolyticus in the Chesapeake Bay has shown that the sudden increase of the bacterial number in water was followed by the

8 Waterborne Pathogens

decomposition of algal bloom in the bay, plausibly due to the breakdown of algal bloom which caused the bacteria living in association with the algae to be released in water (Kaneko and Colwell, 1977). The algal mass breaks down upon reaching limited nutrient condition, subsequently releasing organic matter and inorganic salt along with bacterial cells. These newly released bacteria are now exposed to a large amount of organic nutrient, high salinity, and dissolved oxygen, along with increased pH. These conditions may play role in allowing the algae-associated VBNC bacteria to “resuscitate” into multiplying culturable form in the water (Fig. 1.4). Low Rainfall

Decreased Water Volume

Concentraon of organic maer

Longer sunshine hours, lower temperature (winter)

Medium/long sunshine hours, high temperature (summer)

Algal bloom

Dead and disintegrated algal cells Decreased CO₂ Increased dissolved oxygen Release of nutrients and inorganic salts (increased salinity)

Increased pH

Condions suitable for V. cholerae mulplicaon

Transmission of V. cholerae from environment to community as index case

Epidemic starts due to lack of safe water and sanitaon FIGURE 1.4 Interplay among different climatic, biotic, and abiotic factors of the water and their effect on the multiplication of Vibrio cholerae and the subsequent epidemic.

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This model attempts to provide an answer to the question regarding cholera outbreaks occurring in widely separated places at the same time. It is likely that epidemics result from the decomposition of algal bloom, an event controlled by climatic factors, which promotes the release of pathogen into the water in a favorable condition that accelerates the resuscitation, growth, and propagation. Therefore, the abrupt, concurrent occurrence of the epidemics is accounted for in terms of annually recurring climatic occurrences, translated into changes in the development and conduct of the reservoir and eventually the proliferation of the pathogen in the environment.

6. Transmission of cholera during epidemics Cholera outbreaks occur as a result of the usage of contaminated water for domestic purposes, including washing, bathing, and drinking, as reported in a study that shows that nearly half of the surface water sources in proximity to cholera-infected area are contaminated with V. cholerae (Hughes et al., 1982). Disease is contracted upon ingestion of bacteria in either VBNC or culturable form because bacteria are likely to revert to culturable form from VBNC when ingested. Disease can spread from the index case to the members of the household and even to the members of the neighborhood (Sugimoto et al., 2014). Poor hygiene behavior is one of the factors that play a strong role in the transmission of cholera. There is a notion among people of Bangladesh, especially in rural area, that children’s feces is harmless, when in reality it is one of the main sources of cholera pathogen. Therefore, soiled cloths of cholera-infected children are often washed in nearby “ghaats” (washing points), which is also a common water collection point. Thus, these washing and collection points become a repository of viable V. cholerae. People also feel a sense of shame about children soiling cloths, which leads them to wash the cloth early at dawn to avoid witnesses, followed by the water collection period of the neighbors. This pattern of events locks the community in a continuous “vicious cycle” of cholera transmission.

7. Impact of climate on cholera In this section we will explore the dependence of cholera occurrence on macroscale environmental variables, notably those prominently affected by a shift in climate. The relation between cholera and environmental variables has been broadly investigated. Jutla et al. list a number of drivers associated with cholera, notably, SST and SSH, monsoon rainfall, and air and water temperature (Jutla et al., 2013). A number of models have been developed to determine the probable correlation between environmental variables and cholera incidents (Emch et al., 2008; De Magny et al., 2008; Jutla et al., 2013; Lobitz et al., 2000). These models have been useful largely because of the

10 Waterborne Pathogens

development of satellite imageryeassisted remote sensing technology that permits the measurement of a large range of ocean and meteorological parameters. It has been conclusively demonstrated that cholera epidemics are associated with ocean chlorophyll concentration, a surrogate measure of ocean phytoplankton (Emch et al., 2008; De Magny et al., 2008; Jutla et al., 2013; Lobitz et al., 2000). In both Kolkata, India, and Matlab, Bangladesh, De Magny et al. found statistically significant relation between cholera outbreaks and ocean chlorophyll concentrations (De Magny et al., 2008). However, there was a 1 month lag between chlorophyll concentration peak and cholera outbreaks in Matlab, which was not observed in Kolkata. This lag may have happened because of the distance between Matlab and the ocean, which caused a delay in the phytoplankton’s arrival inland, as explained by the researchers. Air temperature along with ocean chlorophyll was incorporated by Jutla et al. (2013) to expand upon this research in the Himalayan foothills, which required a surrogate for river discharge in their model. They found a strong association between MarcheAprileMay cholera epidemic and the phytoplankton concentration during SeptembereNovember of the previous year. It was explained that this 5-month lag is the consequence of the high river discharge in the months immediately after the phytoplankton peak, which prevented the ocean phytoplankton from entering inland. Cholera epidemic occurred during the lowest river discharge period (DecembereJanuarye February), allowing substantial tidal intrusion. An alternate hypothesis was also proposed by the researchers, stating that the SeptembereNovember peak was caused by the algal decomposition, leading toward the concentration of dissolved organic nutrients and the subsequent proliferation of V. cholerae. The pathogens were then carried by the tidal intrusion inland and ultimately culminating disease breakout in the next month. Islam et al. developed a similar conceptual model incorporating the centrality of the role of cyanobacteria as the environmental reservoir in regulating cholera seasonality (Islam, 1987; Islam et al., 1994d). Lobitz et al. reported similar findings about the relationship between cholera outbreak, SSH, and SST (Lobitz et al., 2000), although another later study failed to replicate them (De Magny et al., 2008). The inconsistency between these studies can be easily explained as the increased SSH can lead to higher phytoplankton along with V. cholerae intrusion. Moreover, increased SST plays role in increased algal growth in the ocean. The link between outbreak and these variables are somewhat distance in terms of the cyanobacterial reservoir hypothesis, which can explain why it might not be observed by all studies. However, the link between phytoplankton and cholera has been consistently reported in all studies. The main takeaway that has been presented in the foregoing survey is that efforts to conceptualize a predictive model for cholera based on environmental signatures have been thus far predominantly based on the costal phytoplankton

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intrusion. However, these models effectively ignore that local aquatic environment such as ponds or rivers may also play vital role in cholera epidemiology. As elucidated in this chapter, these local reservoirs are important water sources for the local community and act as the immediate point of contact during cholera-epidemic onset. Therefore, focusing on the environmental signature of these local and relatively smaller but epidemiologically important reservoirs would enable more accurate prediction, as they directly influence outbreaks. Advanced remote sensing technology currently available can measure chlorophyll concentration in small ponds or river in high resolution.

8. Conclusion Some of the key consequences of climate change are increasing the SST and SSH. As mentioned at the outset, increase in SSH has been identified as one of the 12 key climate change vulnerabilities for Bangladesh, and projections indicate a substantial rise in SSH by 2050. The foregoing discussions demonstrate that these variables are innately associated with the spread and dynamics of cholera, mediated by the growth and activity of its phytoplankton reservoir. This suggests the coming decades will see the exacerbation of emerging cholera outbreaks, which calls for appropriate adaptation measures to deal with this looming threat. Furthermore, indirect effects of climate change, particularly extreme weather events, include population displacement, malnutrition, poor health, and sanitation conditions. As unsafe water and sanitation practices are heavily implicated in the spread of cholera, such indirect effects would compound the already substantial risk posed by the direct effects of climate change. Key adaptive measures to counter these effects of this reemerging waterborne pathogen would include administration of water and sanitation interventions, ranging from provision of microbiologically safe drinking water to hygiene and sanitation education. Cholera prediction efforts can significantly aid these efforts, as an early warning system can be used to effectively target these interventions to the communities anticipating an outbreak. It is important to note, however, that confidence in all modeling efforts must be tempered with the consideration that cholera outbreaks are heavily contingent on human, water and sanitation practices, which is beyond the reach of the powerful remote sensing tools used to generate large volumes of environmental data. Nonetheless, an early warning system with even a coarse approximation of cholera risk can aid in the targeted administration of water and sanitation interventions in anticipation of ensuing epidemics, ultimately leading to an improvement of the prevention and control of this disease.

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References Altizer, S., et al., 2013. Climate change and infectious diseases: from evidence to a predictive framework. Science 341 (6145), 514e519. Banu, S., et al., 2014. Projecting the impact of climate change on dengue transmission in Dhaka, Bangladesh. Environ. Int. 63, 137e142. Baracchini, T., et al., 2017. Seasonality in cholera dynamics: a rainfall-driven model explains the wide range of patterns in endemic areas. Adv. Water Resour. 108, 357e366. Baracchini, T., 2014. Seasonality in Cholera Dynamics: A Rainfall-Driven Model Explains the Wide Range of Patterns of an Infectious Disease in Endemic Areas. Brayton, P., et al., 1987. Enumeration of Vibrio cholerae O1 in Bangladesh waters by fluorescentantibody direct viable count. Appl. Environ. Microbiol. 53 (12), 2862e2865. Caesar, J., et al., 2015. Temperature and precipitation projections over Bangladesh and the upstream Ganges, Brahmaputra and Meghna systems. Environ. Sci. 17 (6), 1047e1056. Colwell, R.R., Huq, A., 1994. Vibrios in the environment: viable but nonculturable Vibrio cholerae. In: Vibrio cholerae and Cholera. American Society of Microbiology, pp. 117e133. Colwell, R., et al., 1985. Viable but non-culturable Vibrio cholerae and related pathogens in the environment: implications for release of genetically engineered microorganisms. Biotechnology 3 (9), 817. Colwell, R., et al., 1990. Environmental aspects of Vibrio cholerae in transmission of cholera. In: Advances in Research on Cholera and Related Diarrhoeas. KTK Scientific Publishers, Tokyo, Japan, pp. 327e343. Colwell, R.R., 1996. Global climate and infectious disease: the cholera paradigm. Science 274 (5295), 2025e2031. Costello, A., et al., 2009. Managing the health effects of climate change: lancet and University College London Institute for Global Health Commission. Lancet 373 (9676), 1693e1733. Dasgupta, S., et al., 2014. Cyclones in a changing climate: the case of Bangladesh. Clim. Dev. 6 (2), 96e110. De Magny, G.C., et al., 2008. Environmental signatures associated with cholera epidemics. Proc. Natl. Acad. Sci. U.S.A. 105 (46), 17676e17681. Dong, J., et al., 2008. Emerging pathogens: challenges and successes of molecular diagnostics. J. Mol. Diagn. 10 (3), 185e197. Emch, M., et al., 2008. Seasonality of cholera from 1974 to 2005: a review of global patterns. Int. J. Health Geogr. 7 (1), 31. Glass, R.I., Black, R.E., 1992. The epidemiology of cholera. In: Cholera. Springer, pp. 129e154. Glass, R.I., et al., 1982. Endemic cholera in rural Bangladesh, 1966e1980. Am. J. Epidemiol. 116 (6), 959e970. Gosling, S.N., et al., 2011. Climate: Observations, Projections and Impacts. Met Office. Hashizume, M., et al., 2010. Cholera in Bangladesh: “climatic components of seasonal variation”. Epidemiology 706e710. Hossain, M., Noiri, E., Moji, K., 2011. Climate change and kala-azar. In: Kala Azar in South Asia. Springer, pp. 127e137. Hughes, J.M., et al., 1982. Epidemiology of eltor cholera in rural Bangladesh: importance of surface water in transmission. Bull. World Health Organ. 60 (3), 395. Huq, S., 2001. Climate Change and Bangladesh. American Association for the Advancement of Science.

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Islam, M., Drasar, B., Bradley, D., 1990. Long-term persistence of toxigenic Vibrio cholerae 01 in the mucilaginous sheath of a blue-green alga, Anabaena variabilis. J. Trop. Med. Hyg. 93 (2), 133e139. Islam, M., et al., 1994a. Isolation of Vibrio cholerae O139 synonym Bengal from the aquatic environment in Bangladesh: implications for disease transmission. Appl. Environ. Microbiol. 60 (5), 1684e1686. Islam, M.S., et al., 1994b. Detection of non-culturable Vibrio cholerae O1 associated with a cyanobacterium from an aquatic environment in Bangladesh. Trans. R. Soc. Trop. Med. Hyg. 88 (3), 298e299. Islam, M.S., Drasar, B.S., Sack, R.B., 1994c. The aquatic flora and fauna as reservoirs of Vibrio cholerae: a review. J. Diarrhoeal Dis. Res. 87e96. Islam, M.S., Drasar, B.S., Sack, R.B., 1994d. Probable role of blue-green algae in maintaining endemicity and seasonality of cholera in Bangladesh: a hypothesis. J. Diarrhoeal Dis. Res. 245e256. Islam, M., et al., 1999. Association of Vibrio cholerae O1 with the cyanobacterium, Anabaena sp., elucidated by polymerase chain reaction and transmission electron microscopy. Trans. R. Soc. Trop. Med. Hyg. 93 (1), 36e40. Islam, M., et al., 2002. Involvement of the hap gene (mucinase) in the survival of Vibrio cholerae O1 in association with the blue-green alga, Anabaena sp. Can. J. Microbiol. 48 (9), 793e800. Islam, M., et al., 2009. Effects of local climate variability on transmission dynamics of cholera in Matlab, Bangladesh. Trans. R. Soc. Trop. Med. Hyg. 103 (11), 1165e1170. Islam, M.S., et al., 2015. Role of phytoplankton in maintaining endemicity and seasonality of cholera in Bangladesh. Trans. R. Soc. Trop. Med. Hyg. 109 (9), 572e578. Islam, M.S., 1987. Studies of Aquatic Flora as Possible Reservoirs of Toxigenic “Vibrio cholerae” 01. Islam, M.S., 1990. Increased toxin production by Vibrio cholerae O1 during survival with a green alga, Rhizoclonium fontanum, in an artificial aquatic environment. Microbiol. Immunol. 34 (7), 557e563. Jutla, A.S., Akanda, A.S., Islam, S., 2013. A framework for predicting endemic cholera using satellite derived environmental determinants. Environ. Model. Softw. 47, 148e158. Kabore´, S., et al., 2018. Occurrence of Vibrio cholerae in water reservoirs of Burkina Faso. Res. Microbiol. 169 (1), 1e10. Kaneko, T., Colwell, R.R., 1977. The annual cycle ofVibrio parahaemolyticus in Chesapeake Bay. Microb. Ecol. 4 (2), 135e155. Khan, M.U., et al., 1984. Presence of vibrios in surface water and their relation with cholera in a community. Trop. Geogr. Med. 36 (4), 335e340. Kreft, S., et al., 2013. Global Climate Risk Index 2014. Who Suffers Most from Extreme Weather ´ 31. Events, p. 1A Lobitz, B., et al., 2000. Climate and infectious disease: use of remote sensing for detection of Vibrio cholerae by indirect measurement. Proc. Natl. Acad. Sci. U.S.A. 97 (4), 1438e1443. Longini Jr., I.M., et al., 2002. Epidemic and endemic cholera trends over a 33-year period in Bangladesh. J. Infect. Dis. 186 (2), 246e251. Mamun, A., Rahman, A., Afrooz, N., 2018. A socio-economic analysis of private plant nursery business in Bangladesh. Agriculturists 16 (02), 102e114. Martin, A.R., et al., 1969. Epidemiologic analysis of endemic cholera in urban East Pakistan, 1964e1966. Am. J. Epidemiol. 89 (5), 572e582. McCormack, W.M., et al., 1969. Endemic cholera in rural East Pakistan. Am. J. Epidemiol. 89 (4), 393e404.

14 Waterborne Pathogens Merson, M.H., et al., 1980. Epidemiology of cholera and enterotoxigenic Escherichia coli diarrhoea. In: Cholera and Related Diarrheas. Karger Publishers, pp. 34e45. Metcalf, C.J.E., et al., 2017. Identifying climate drivers of infectious disease dynamics: recent advances and challenges ahead. Proc. R. Soc. Biol. Sci. 284 (1860), 20170901. Nicholls, R.J., et al., 2018. Ecosystem Services for Well-Being in Deltas: Integrated Assessment for Policy Analysis. Springer. Pollitzer, R., 1959. Cholera: With a Chapter on World Incidence. World Health Organization. Rahman, M.R., Lateh, H., 2016. Spatio-temporal analysis of warming in Bangladesh using recent observed temperature data and GIS. Clim. Dyn. 46 (9e10), 2943e2960. Reid, H.L., et al., 2012. Characterizing the spatial and temporal variation of malaria incidence in Bangladesh, 2007. Malar. J. 11 (1), 170. Sack, R.B., Barua, D., 1964. The fluorescent antibody technique in the diagnosis of cholera. Indian J. Med. Res. 52, 848e854. Samadi, A., et al., 1983. Seasonality of classical and El tor cholera in Dhaka, Bangladesh: 17-year trends. Trans. R. Soc. Trop. Med. Hyg. 77 (6), 853e856. Sugimoto, J.D., et al., 2014. Household transmission of Vibrio cholerae in Bangladesh. PLoS Neglected Trop. Dis. 8 (11), e3314. Tamplin, M.L., et al., 1990. Attachment of Vibrio cholerae serogroup O1 to zooplankton and phytoplankton of Bangladesh waters. Appl. Environ. Microbiol. 56 (6), 1977e1980. Vouga, M., Greub, G., 2016. Emerging bacterial pathogens: the past and beyond. Clin. Microbiol. Infect. 22 (1), 12e21. Watts, N., et al., 2018. The Lancet Countdown on health and climate change: from 25 years of inaction to a global transformation for public health. Lancet 391 (10120), 581e630.

Chapter 2

Ubiquitous waterborne pathogens D.N. Magana-Arachchi1, R.P. Wanigatunge2

1 Molecular Microbiology & Human Diseases Unit, National Institute of Fundamental Studies, Kandy, Sri Lanka; 2Department of Plant and Molecular Biology, University of Kelaniya, Kelaniya, Sri Lanka

1. Introduction In July 2010, the United Nations General Assembly (UNGA) univocally recognized the human right to water and sanitation and acknowledged that clean drinking water and sanitation are essential to the realization of all human rights (UNGA, 2010). However, due to inadequacy, unsafe, inaccessibility, and unaffordability of water, most of the people globally are deprived of this universal right. According to the Joint Monitoring Program (JMP) report, some 3 in 10 people worldwide, or 2.1 billion, lack access to safe, readily available water at home and 6 in 10, or 4.5 billion, lack safely managed sanitation (WHO and UNICEF, 2017). Due to the global efforts, billions of people have gained access to basic drinking water and sanitation services since 2000, but people in many countries are still lacking clean water and proper sanitation in their homes, healthcare facilities, and schools. Hence health of all these people is at a risk, affecting mainly the infants and young children. Water, sanitation, and hygiene were responsible for 829,000 deaths from diarrheal disease in 2016. It is estimated that every year, 361,000 children under 5 years of age die because of diarrhea. In addition, poor sanitation and contaminated water are also linked to transmission of waterborne diseases such as cholera, dysentery, hepatitis A, and typhoid (WHO and UNICEF, 2017). In September 2015, Member States of the United Nations adopted the 2030 Agenda for Sustainable Development (UNSD, 2015) and Goal 6 of Sustainable Development Goals is to “Ensure availability and sustainable management of water and sanitation for all.” Targets were set by considering the freshwater cycle as a whole. Member States try to achieve these targets by improving the standard of water, sanitation, and hygiene (WASH) services; increasing treatment, recycling, and reuse of wastewater; improving efficiency and ensuring sustainable withdrawals; and protecting water-related ecosystems Waterborne Pathogens. https://doi.org/10.1016/B978-0-12-818783-8.00002-5 Copyright © 2020 Elsevier Ltd. All rights reserved.

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as part of an integrated approach to water resources management. They also address the means of implementation for achieving these development outcomes (WHO and UNICEF, 2017). A pathogen means an agent that causes disease to a host, and waterborne pathogens are the causative agents (usually living organisms) for diseases that are being transmitted through water. Water pollution can occur due to chemical and/or biological contaminants. These waterborne pathogens thrive in polluted waters, especially contaminated with human feces or/and urine. People could get exposed to these microorganisms while drinking water, by eating food prepared with contaminated water, bathing, during recreational activities, or even sometimes in healthcare facilities during dialysis. This exposure could be limited to an individual or it can be a community outbreak. The morbidity and mortality caused by contaminated water are enormous and it could only be controlled by providing microbiologically safe and toxin-free water for drinking, cooking, and other recreational activities. Surface waters in most countries are polluted with pathogens and this is widely recorded in the developing world. Consumption of these waters leads to waterborne disease outbreaks (WBDOs) (Patel et al., 2016). A recent study from China has shown that potentially pathogenic bacteria were ubiquitous across all of the 16 urban sampled surface waters, and Proteobacteria and Bacteroidetes were the most commonly detected phyla accounting for 21.9% e78.5% and 19.1%e74.7% of sequences, respectively (Jin et al., 2018). Intermittent water supply (IWS) is being practiced throughout low- to middleincome countries. A study was conducted by Bivins et al. (2017) with existing data using reference pathogens Campylobacter, Cryptosporidium, and rotavirus (RV) as conservative risk proxies for infections via bacteria, protozoa, and viruses, respectively. Their findings indicated that the median daily risk of infection is 1 in 23,500 for Campylobacter, 1 in 5,050,000 for Cryptosporidium, and 1 in 118,000 for RV. Based on these risks, IWS may account for 17.2 million infections causing 4.52 million cases of diarrhea, 109,000 diarrheal disability-adjusted life years (DALYs), and 1560 deaths each year. The WHO health-based normative guideline for drinking water is 10
6 DALYs per person per year and it is likely that the value of diarrheal disease associated with IWS will be surpassing the WHO value. When ensuring clean water for drinking and other activities, proper management guidelines are needed to be followed. Preparation of these guidelines is not an easy task and it needs thorough understanding about the pathogenic nature of the organisms considering their shape, size, composition, and structure, their survival and behavior, and how they transmit in different waterbodies. Many countries use indicator organisms to assess the microbiological quality of drinking water. Most widely used bacteria are the enteric bacterial coliforms belonging to the family Enterobacteriaceae. In addition to being able to identify the microbial contamination of drinking water with human waste, these organisms are capable of identifying the fecal

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contaminations in waters used for recreational activities as well as in shellfish production. The presence of these pathogenic organisms in waterbodies is being monitored regularly in most developed countries as new tools are available to them due to the advances made in medical and scientific research. Modern technologies have also been incorporated into the water treatment plants for the effective removal or deactivation of these waterborne pathogens, thereby minimizing the outbreaks and the risk due to exposure. In this chapter we will be focusing on the ubiquitous waterborne pathogens which cause deadly diseases and outbreaks affecting young and old globally. Etiological agents for substantial amount of waterborne diseases are “classical” waterborne pathogens. However, fresh organisms and new strains from already known pathogens are being identified and that present important additional challenges to both the water and public health sectors. Hence we will outline the potential waterborne pathogens including Helicobacter pylori, Tsukamurella, Cystoisospora belli, and Microsporidia and also Bacillus species and toxic cyanobacteria that needed to be paid attention to supply clean water, prevent mishaps, and protect and improve public health. Listed pathogens for this chapter were selected from the WHO Guidelines for drinking water quality, fourth edition (2011) and from Global Waterborne Pathogen Project (GWPP) (Rusinol and Girones, 2017). Readers could gain extra knowledge on these organisms by referring to the original articles which are being included in the references. Furthermore, descriptive diagrams of these organisms can be found in the book chapter by Bridle (2013).

2. Waterborne pathogens This first section is based on ubiquitous waterborne pathogens including bacteria, viruses, protozoa, and helminths, which will be discussed in chronological order, and the causative diseases and mode of transmission are summarized schematically in Fig. 2.1 for the readers’ benefit.

2.1 Waterborne bacteria Bacterial pathogens are classical etiological agents of waterborne diseases globally. These organisms can occur ubiquitously in many aquatic habitats and humid soils. They are an important part of the biocenosis in various substrates or water systems, especially in their preferred habitats, the biofilms. According to WHO, from the mortality of water-associated diseases, more than 50% are due to microbial intestinal infections. There are limitations in many of the established methods used in water quality assessments, and new approaches to health-related monitoring are being introduced by WHO that can overcome many of the weaknesses in current methods and provide additional tools for reducing disease risks (WHO, 2003).

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FIGURE 2.1 Generalized overview of ubiquitous waterborne pathogens, route of transmission, and sites of infection.

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2.1.1 The genus Vibrio Vibrios are small, curved-shaped or rods, facultative anaerobes with a single polar flagellum, belonging to family Vibrionaceae of order Vibrionales that are nonespore-forming and Gram-negative with a size of approximately 1.5e 3.0 mm  0.5 mm. Cells of Vibrio cholerae, Vibrio parahaemolyticus, and Vibrio vulnificus possess pili (fimbriae) structures comprising of protein TcpA. This TcpA formation is co-regulated with cholera toxin expression and is a key determinant of in vivo colonization. These are primarily aquatic bacteria, common in marine and estuarine environments, living free or on the surfaces and in the intestinal contents of marine animals. Around 12 Vibrio species can infect humans. V. cholerae is, by far, the most important among them. Vibrio fluvialis, Grimontia hollisae (formerly Vibrio hollisae), and Vibrio mimicus can cause diarrhea or infections of the gastrointestinal tract. Vibrio furnissii has been isolated from a few individuals with diarrhea, but there is no evidence that it can actually cause this pathology. Cholera is a well-known disease since 19th century and it is topping the list of microbial waterborne diseases. V. cholerae is a very diverse bacterial species. It has more than 200 serovarieties, characterized by the structure of the lipopolysaccharide (O antigens). Only serovarieties O1 and O139 are involved in true cholera (Weintraub, 2003). Some other serovarieties can cause gastroenteritis. The serovariety O1 is subdivided into classical and El Tor biotypes based on their biochemical properties and phage susceptibilities. Only toxigenic strains have the CTXF segment (7e9.7 kb) of the chromosome and this carries at least six genes which have the potential to encode cholera toxin. During chromosome replication, the CTXF fragment is able to make an autonomous copy creating an independent plasmid. The plasmid produces virus-like particles, the CTXF bacteriophages, which in turn infect nontoxigenic strains (Cabral, 2010). Epidemic and pandemic strains of V. cholerae contain another chromosomal segment designated as Vibrio Pathogenicity Island (VPI). VPI is 39.5 kb in size and contains two ToxR-regulated genes: a regulator of virulence genes (ToxT) and a gene cluster containing colonization factors, including the toxin co-regulated pili. Pathogen can be transmitted by the contaminated water or food via the fecaleoral route. V. cholerae O1 or O139 strains are common in estuaries being isolated from estuarine animals, such as birds, frogs, fishes, and shellfish, and are able to survive and multiply on the surface of phytoplankton and zooplankton cells. 2.1.2 The genus Salmonella Salmonellae are rod-shaped, motile by peritrichous flagella, belonging to family Enterobacteriaceae of order Enterobacteriales that are nonesporeforming, Gram-negative bacteria with a size of a rod being 0.7e1.5 mm by

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2.2e5.0 mm producing colonies approximately 2e4 mm in diameter. Salmonellae have several endotoxins: antigens O, H, and Vi. Salmonella enterica subsp. enteric serovar Enteritidis is the most frequently isolated serovar from humans all over the world. However, other serovars can be predominant and each outbreak had been associated with a different serotype: Mbandaka, Livingstone, and Typhi Viþ. The major habitat of Salmonella is the intestinal tract of humans and animals and is frequently found in environmental samples because they are excreted by humans as well as animals. Municipal sewage, agricultural waste, and storm water runoff are the main sources of these pathogens in natural waters and they do not multiply much in natural environments but can survive several weeks in water and soil when environmental factors are favorable. Paratyphi or non-Typhi serovars of Salmonellae are more common in the environment. From environmental sources, 73% of the isolates were from tap water in which commonly observed organisms being serovars: Corvallis, Enteritidis, and Anatum (Aissa et al., 2007). A study reported a total of 19 Salmonella serotypes in a comparative study carried out in rivers Aliakmon and Axios, in northern Greece (Arvanitidou et al., 2005).

2.1.3 The genus Shigella Shigellae are rod-shaped and nonmotile, belonging to family Enterobacteriaceae of order Enterobacteriales that are nonespore-forming, Gram-negative with a size of a cell being 0.4e0.6 mm by 1.0e3.0 mm long. There are four serogroups in Shigella: Shigella dysenteriae (serogroup A) with 1e15 serotypes, Shigella flexneri (serogroup B) serotypes 1e8 with 9 subtypes, Shigella boydii (serogroup C) with serotypes 1e19, and Shigella sonnei (serogroup D) with one serotype. The four serogroups differ in their epidemiology and outbreaks have been attributed to the community water supplies which were not properly chlorinated. Shigella has a complex antigenic pattern and the serogrouping is based on their somatic O antigens. Shigella emerged from Escherichia coli during evolution. The acquisition and evolution of the pathogenicity island, which encodes all of the genes required for cell invasion and phagolysosomal lysis, permitted a major alteration in pathogenesis. Shigella is the causative agent for the disease shigellosis or bacillary dysentery, naturally spread by fecalcontaminated drinking water or food or by direct contact with an infected person and considered as a disease affecting the under developed displaced people who are lacking the basic hygienic facilities. 2.1.4 The genus Escherichia Bacteria in genus Escherichia are rod-shaped, nonespore-forming, Gramnegative bacteria belonging to family Enterobacteriaceae of order Enterobacteriales. Commonly found E. coli have a size of 2.0e0.5 mm in

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diameter. E. coli is a natural and essential part of the bacterial flora in the gut of humans and animals. Most E. coli strains inhabiting colon are nonpathogenic, but certain serotypes have a role in intestinal and extraintestinal diseases, such as urinary tract infections. There are six different groups of E. coli strains isolated from intestinal diseases based on epidemiological evidence, phenotypic traits, clinical features of the disease, and specific virulence factors. Among them, enterotoxigenic E. coli O148, enterohemorrhagic E. coli O157, and enteroinvasive E. coli O124 serotypes are major disease-causing organisms and can be transmitted through contaminated water. Enterotoxigenic E. coli (ETEC) serotypes can cause infantile gastroenteritis. Disease is caused due to consumption of ETEC-contaminated food or water and is characterized by profuse watery diarrhea continuing for several days leading to dehydration and malnutrition in young children. ETEC serotype 148 is one of the causative agents of “travelers’ diarrhea” that affects individuals who are involved in global traveling. Shiga toxin-producing E. coli O157:H7 is considered as food and waterborne pathogen that causes diarrhea, hemorrhagic colitis, and hemolytic uremic syndrome (HUS) in humans in both sporadic cases and outbreaks (Wasey and Salen, 2019). The incubation period is 3e4 days, and the symptoms last for 7e10 days. HUS associated with Shiga toxin-producing E. coli O157:H7 cause acute renal failure mostly in children. These bacteria are naturally not a concern in treated drinking water, but outbreaks related to consumption of contaminated water or use of surface water for recreational activities have been documented (Bruneau et al., 2004). Enterohemorrhagic E. coli have also been isolated from ponds, streams, wells, and water troughs, and they can survive for months in manure and water-trough sediments. Personal contacts are an important mode of transmission and disease spread through the orale fecal route. Enteroinvasive E. coli act as same as Shigella. They are capable of invading and multiplying in the intestinal epithelial cells of the distal large bowel in humans. The illness is characterized by abdominal cramps, diarrhea, vomiting, fever, chills, a generalized malaise, and the appearance of blood and mucus in the stools of infected individuals. E. coli O124 had been isolated from cases of gastroenteritis, enterocolitis, and dysentery. Food prepared by using water contaminated with human waste could cause the disease in humans.

2.1.5 The genus Burkholderia Bacteria in the genus Burkholderia are straight or slightly curved, rod-shaped, nonespore-forming and Gram-negative, and motile due to a single or multiple polar flagella except in one species, belonging to family Burkholderiaceae of order Burkholderiales. The genus comprises of 60 species of obligatory

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aerobes that are ubiquitous in nature and are waterborne pathogens. Clinically relevant species include Burkholderia cepacia complex species, Burkholderia pseudomallei, Burkholderia mallei, Burkholderia gladioli. B. pseudomallei is with a diameter of 0.8 mm, and a length of 1.5 mm can be present in soil or water whether it is surface or ground. Melioidosis is a life-threatening disease caused by B. pseudomallei and is endemic to southeast Asians and to northern Australians and randomly affects people living close to the equator. It is more common during the monsoon season than in dry months and literature confirms that it became more prevalent after 2004 Tsunami (Currie et al., 2008). Melioidosis has been reported from Thailand and the disease is highly endemic to the northeast. Most infected community is agricultural farmers with repeated environmental exposure (Limmathurotsakul et al., 2013). Water supplyerelated melioidosis has also been documented and the disease could be acute or chronic. Signs and symptoms may include pain in the chest, bones, or joints; cough; skin infections, lung nodules, and pneumonia, which is a lifethreatening infection that is estimated to account for nearly 89,000 deaths per year worldwide (Wiersinga et al., 2018). Melioidosis is an emerging disease in Sri Lanka (Corea et al., 2012).

2.1.6 The genus Campylobacter The bacteria in genus Campylobacter are Gram-negative, 0.5e8 mm long, and 0.2e0.5 mm wide with characteristically curved, spiral, or S-shaped cells belonging to the family Campylobacteraceae in order Campylobacterales. This genus consists of 29 species and 12 subspecies. The most important Campylobacter species in human gastroenteritis is Campylobacter jejuni followed by Campylobacter coli, Campylobacter lari, and Campylobacter fetus. Campylobacter enteritis was the causative agent for 8.5% of the total burden of diarrheal disease, standing fourth after RV, cryptosporidiosis, and E. coli diarrhea (combined enterotoxigenic and enteropathogenic E. coli infections) (Murray et al., 2012). Disparities have been observed between developed and developing countries in the epidemiology and demography of Campylobacter infections. In developing countries, symptomatic disease is most commonly seen only during the first 2 years of life, and symptomatic illness in adults is scarce because of the endemic nature. In developed world, the most common symptoms include an acute, self-limiting gastroenteritis, with an incubation period of 2e5 days, whereas in developing nations, watery diarrhea is mostly observed. This is considered also as a zoonotic disease and wide variety of animals, especially poultry, wild birds, cattle, and sheep carry high numbers of C. jejuni and C. coli as commensals in their intestines. Fecal contamination of food, recreational water, and drinking water contributes to human infections and the fecal material of infected persons spread the organisms back to environment through sewage plants and toilets.

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2.1.7 The genus Francisella The genus Francisella is 0.7e1.7 mm in size, nonmotile, Gram-negative, strictly aerobic, and facultative intracellular coccobacilli species. The type species of the genus is the Francisella tularensis, which contains four subspecies, i.e., tularensis, holarctica, mediasiatica, and novicida. F. tularensis is a highly infectious bacterium causing disease in mammals including humans and a potential bioterror weapon (Colquhoun et al., 2014). Tularemia is a zoonotic infection caused by F. tularensis mainly transmitted to humans through arthropod bites, direct contact with infected animals, and inhalation or ingestion of contaminated water. The organism can persist in water or mud at least for 1 year and that indicates the environment may be important reservoirs for this pathogen. Recent and historical outbreaks indicate that environmental exposure to the organism is a significant source of morbidity. 2.1.8 The genus Legionella Legionellae are rod-shaped, Gram-negative bacteria being the only genus in family Legionellaceae. The genus includes 52 validated species with 71 serotypes out of which 24 Legionella species are described as occasional human pathogens. Legionella pneumophila cause Legionnaires’ disease, which is a sever type of pneumonia occurring worldwide. The transmission can occur via inhalation of contaminated aerosols generated by cooling towers, bath tubs, whirlpools, ornamental fountains, and showers. In nature, Legionella live in freshwater and rarely cause illness. Outbreaks of Legionnaires’ disease are often associated with man-made water settings, with large or complex water systems. Most outbreaks have been due to L. pneumophila, serogroup 1, and although this may be due to increased virulence, it may simply reflect the greater prevalence of this particular organism (Yu et al., 2002). Biofilms and free-living amebae are considered to serve as main environmental reservoirs for L. pneumophila and represent a potential source of drinking water contamination, resulting in a potential health risk for humans. 2.1.9 Mycobacterium avium complex The genus Mycobacterium belongs to family Mycobacteriaceae of order Actinomycetales. The Mycobacterium avium complex (MAC) consists of 28 serovars of two distinct species: Mycobacterium avium and Mycobacterium intracellulare. MAC has been recovered from drinking water systems both before and after treatment, hot water heaters, freshwater, brackish, sea water, and wastewater, occasionally being high in numbers, and the infection to humans occurs through the inhalation of aerosolized droplets containing M. avium cells. The organisms of MAC have the ability to survive and grow under diverse and extreme conditions. Hence mycobacteria are highly resistant to chlorine and other chemical disinfectants as such standard drinking water treatments

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will not completely eliminate MAC organisms but can minimize the risk. The symptoms encountered with MAC infections result from colonization of either the respiratory or the gastrointestinal tract, with possible dissemination to other locations in the body.

2.2 Waterborne viruses Diarrheal disease and WBDOs from drinking, recreational, and groundwaters are often caused by waterborne viruses, which tend to be more persistent in the environment than bacteria (Gibson, 2014). WHO has classified adenovirus (AdV), astrovirus (AstV), hepatitis A and E viruses, RV, norovirus, and other caliciviruses and enteroviruses, including coxsackieviruses and polioviruses as water-transmitted viral pathogens having a moderate to high health significance (WHO, 2011). Also, polyomaviruses and cytomegalovirus that are excreted through urine can potentially be spread through water. Influenza and coronaviruses have been proposed as organisms that can be transmitted through drinking water, but evidences are lacking. These viruses are mostly associated with gastroenteritis, which can cause diarrhea as well as other symptoms including abdominal cramping, vomiting, and fever. Some of these same viruses could also cause more severe illnesses including encephalitis, meningitis, myocarditis (enteroviruses), cancer (polyomavirus), and hepatitis (hepatitis A and E viruses) (WHO, 2011).

2.2.1 Adenoviruses AdVs, belonging to the family Adenoviridae, genus Mastadenovirus, have over 51 serotypes differentiated to six subgroups (A to F), which are the causative agents of many human diseases. They are 80e90 nm in size containing double-stranded linear DNA and a nonenveloped icosahedral shell that has slender projections from each of its 12 vertices. They can infect many organs in the body including the eye, upper respiratory tract, lower respiratory tract, gastrointestinal tract (gastroenteritis and intussusception), urinary bladder, central nervous system, and genitalia. The enteric adenoviruses types 31, 40, 41, and subgenus F are responsible for the majority of adenovirusmediated cases of gastroenteritis. Pathogenicity of the virus varies with the species and serotype, and organ specificity and disease patterns appear to be serotype-dependent. Human adenoviruses are transmitted by the fecaleoral route and through inhalation of water droplets. They are listed as pathogens of childhood gastroenteritis as most affected are being children of under 5 years of age. AdV resistance to purification and disinfection processes (i.e., UV inactivation) and the virus’s ability to survive in the environment have increased the importance of monitoring AdVs in water (Jiang, 2006). Theses adenoviruses are being documented everywhere in the world, without any seasonal

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variability and could be found in drinking water if not properly treated, in raw sewage, polluted waters such as rivers and dams, swimming pools, and even in shellfish.

2.2.2 Astroviruses AstVs are nonenveloped, icosahedral viruses belonging to family Astroviridae. They are 28e41 nm in size, containing positive-sense, single-stranded RNA, genome of approximately 7 kb in size. They have been classified into two genera: Mamastrovirus and Avastrovirus. Genera Mamastrovirus and Avastrovirus cause infection to mammalians and avian, respectively. Three divergent groups of human astroviruses (HAstVs) have been identified and according to research, the classic AstV group contains eight serotypes accounting for less than 10% of all acute nonbacterial gastroenteritis in children worldwide without any geographical boundaries. Children get infected in the first few years of life regardless of their level of hygiene, quality of water, food or sanitation, or type of behavior. Although children are vulnerable, there are reports of disease in normal healthy adults (Pager and Steele, 2002) and also immunocompromised individuals (Gonza´lez et al., 1998). This infection induces mild, watery diarrhea that lasts 2e3 days, associated with vomiting, fever, anorexia, and abdominal pain. In comparison to RV or calicivirus infection, infections due to AstVs have a longer incubation period. These viruses can be transmitted by the contaminated water via the fecaleoral route, and higher incidence has been recorded in cold months. In temperate regions, most AstV infections are during winter, whereas in tropics, infections occur during rainy months. These viruses are being detected both in surface and groundwaters which are being used as drinking water sources, freshwater, and marine waters as well as in wastewater effluents. Moreover, waterborne transmission of HAstVs has been suggested as a risk of digestive morbidity for the general population (Gofti-Laroche et al., 2003). Chlorine and other disinfectants are effective for the inactivation of these viruses in water. 2.2.3 Caliciviruses Caliciviruses are nonenveloped, 27e40 nm single-stranded RNA viruses in the family Caliciviridae. They are an important group of human viruses capable of causing gastrointestinal disease in humans that may be found in waters intended by humans for drinking, recreation, and shellfish growing. The International Committee on Taxonomy of Viruses changed the calicivirus nomenclature and classified into four genera: Vesivirus, Lagovirus, Norovirus, and Sapovirus. Sapoviruses (SaVs) and noroviruses (NoVs) are included in the latest US Drinking Water Contaminant Candidate List (CCL) (Rusinol and Girones, 2017). They get spread by the fecaleoral route and are found in contaminated surface and groundwaters. The presence of caliciviruses in

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groundwaters is an important consideration, as a number of outbreaks have been linked to these drinking water sources (often from shallow wells and springs) (Schaub and Oshiro, 2000).

2.2.4 Noroviruses Noroviruses (NoVs) (formerly Norwalk virus) were first identified following an outbreak of enteric illness among children and adults in the town of Norwalk, Ohio (Adler and Zickl, 1969). They are a group of nonenveloped, singlestranded RNA viruses with an icosahedral symmetry classified into the genus Norovirus of the family Caliciviridae with a size of 27e32 nm. Most norovirus genomes contain three open reading frames (ORFs). They have rough, nondistinct borders and lack the calyx appearance. Noroviruses are divided into five genogroups (GI to GV), three of which (GI, GII, and GIV) cause human disease. This virus is extremely infectious and humans are the only known reservoir for human norovirus. NoVs cause acute onset of projectile vomiting and diarrhea, sometimes with low-grade fever, headache, and malaise. Symptoms are usually self-limited, lasting for 24e72 h. The incubation period is usually 24e48 h, but onset of symptoms as soon as 10 h after exposure has been reported. Disease outbreaks have been associated with consumption of these viruses in drinking water and also in contaminated shellfish (Maunula et al., 2005; Boxman et al., 2006). 2.2.5 Sapoviruses Sapovirus (SaV) is one of the etiological agents of human gastroenteritis, is named after the Japanese city Sapporo, where it was first discovered (Chiba et al., 1979). SaV is an RNA virus with a nonsegmented, positive-sense, singlestranded RNA molecule of approximately 7.3e7.5 kb, belonging to the family Caliciviridae. Genome organization of SaVs differs to NoV and contains only two ORFs instead of three. SaVs have a nonenveloped viral capsid with icosahedral symmetry and display a characteristic surface that has cup-shaped depressions on the surface, formed by the 32 cups or “calices,” which is a typical calicivirus morphology. SaVs show a high level of diversity in their genomes and are currently divided into at least five genetically distinct genogroups. Infections in humans are caused by viruses of genogroup GI, GII, GIV, and GV, and at present human SaV genogroups are classified into 16 genotypes. The disease outbreaks are reported in all age groups including the elderly people (Lee et al., 2012). SaVs are transmitted from person to person via fecaleoral routes and through contaminated foods and water. 2.2.6 Enteroviruses The waterborne polioviruses, coxsackieviruses, echoviruses, hepatoviruses, and certain unclassified enteroviruses together as a group named as enteroviruses are belonging to the family Picornaviridae. They are small in size,

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22e30 nm in diameter, and nonenveloped, and the virions are relatively simple, consisting of a protein capsid surrounding a single-stranded, positivesense RNA genome and it is assumed that only reservoir for enteroviruses are humans. They are present mainly in sewage contaminated with human feces but can be found in groundwaters, coastal river and marine waters, sewage treatment plants and from solid waste landfills, and insufficiently treated drinking water. These have been identified as sensitive to formaldehyde, hydroxylamine, UV, ionizing irradiations, and also to ozone but cannot be inactivated with changing pH or with usual chlorination. It is assumed that infections from enteroviruses are associated with poverty and poor hygienic conditions.

2.2.7 Hepatovirus A Hepatovirus A (HAV) is a nonenveloped virus with an icosahedral capsid of about 27e32 nm, single-stranded having an RNA genome of approximately 7.5 kb and belongs to the family Picornaviridae. HAV is the causative agent of type A viral hepatitis and only one serotype has been reported (Cristina and Costa-Mattioli, 2007). Virus transmission occurs through the fecaleoral route by direct contact with an infected person or exposure to contaminated water or consumption of contaminated food. The incidence of HAV shows distinct patterns of geographic distribution and being related to standards of hygiene and sanitation, demographic factors and socioeconomic conditions of the population. Most of the infections occur in Africa and Asia, followed by Central and South America, Eastern Europe are considered as areas of intermediate endemicity. Children are more vulnerable to disease in highly endemic areas while adolescents and adults are susceptible to infection in intermediate endemic areas (WHO, 2012). 2.2.8 Hepatovirus E Hepatovirus E (HEV) is a nonenveloped, positive-sense, single-stranded RNA genome of 7.2 kb in length and belongs to the family Hepeviridae. Family Hepeviridae contains two genera: Orthohepevirus and Piscihepevirus. Four main genotypes of HEV (HEV-1, HEV-2, HEV-3, and HEV-4) belonging to the Orthohepevirus A species are able to infect humans. HEV is primarily transmitted by fecaleoral routes through contaminated foods and water in endemic areas. Also, zoonotic and person-to-person transmission is possible. HEV causes acute hepatitis E in human and an infection is considered to be endemic in many developing countries in Africa and Asia. HEV genotypes 1 and 2 cause epidemic and endemic diseases in developing countries, mainly through contaminated drinking water, while genotypes 3 and 4 cause autochthonous infections mainly in developed countries through a unique zoonotic foodborne transmission (Khuroo et al., 2016).

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2.2.9 Rotaviruses RVs are nonenveloped, double-stranded RNA viruses, belonging to the family Reoviridae. RV is composed of the outer capsid, inner capsid, and core, and genome is composed of 11 segments of double-stranded RNA, which code for six structural and five nonstructural proteins. RV is mainly classified into seven groups (AeG) based on the antigenicity of the inner capsid protein VP6 and genomic characteristics. Among them, rotavirus group A (RVA) strains with distinct G-genotype and P-genotype are the major etiological agents in humans worldwide. Infection with RVA is the most common cause of diarrheal disease among infants and young children and one of the common causes of death in children under 5 years of age (Walker et al., 2013). Virus transmission occurs through the fecaleoral route by direct contact with an infected person and possibly by the respiratory route. RV causes an estimated 2 million hospitalizations and 450,000 deaths among children annually, and the majority of deaths are reported from developing countries in Asia and Africa (Wang et al., 2014; Liu et al., 2015). The WHO has recommended that the use of RV vaccines in routine immunization programs worldwide to reduce the burden of disease (WHO, 2009). 2.3 Waterborne protozoa Protozoan parasites were the most frequently identified etiologic agents in WBDOs in 1990s. Further from 1978 through 1991, Giardia lamblia was the most commonly identified pathogen, while in 1992, the numbers of outbreaks reported for giardiasis and cryptosporidiosis were matching. Naegleria fowleri, Acanthamoeba spp., and Entamoeba histolytica are also considered as etiologic agents in WBDOs. Since the potential threat of infection via the waterborne route is being recognized for many of these protozoans, it is crucial that the water industry pays its attention to finding ways to detect these emerging and well-recognized protozoan pathogens in water (Marshall et al., 1997).

2.3.1 The genus Cryptosporidium Cryptosporidia are zoonotic protozoan parasites with worldwide distribution, consisting of 27 species and more than 60 genotypes. Among Cryptosporidium species identified, Cryptosporidium hominis and Cryptosporidium parvum are the major disease-causing organisms in human. They cause cryptosporidiosis which is a gastrointestinal illness that can last for several days to several weeks. This infection is commonly found in children, immunocompromised individuals, and workers who are frequently exposed to wastewater. The major routes of transmission are not only water and food but also person-to-person contact and respiratory transmission is possible.

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2.3.2 The genus Giardia Giardia are flagellated protozoan parasites belonging to the phylum Metamonada that cause giardiasis, a diarrheal disease in humans and other mammals throughout the world. Since 1920, six Giardia species have been described; Giardia duodenalis (syn. Giardia intestinalis and G. lamblia) is the major disease-causing organisms in human. Risk from Giardia can be through occupational, accidental, or recreational exposure to surface waters. Brodsky et al. (1974) reported that water contaminated with G. lamblia cysts causes travel-related giardiasis in tourists in certain areas of the world. Giardia species have two major stages in their life cycle, i.e., rapidly multiplying trophozoites and cysts. Cysts are excreted with feces and survive in a variety of environmental conditions. They can be transmitted through contaminated water, food, or direct fecaleoral route. 2.3.3 Entamoeba histolytica E. histolytica belongs to the family Entamoebidae, an invasive, pathogenic protozoan causing amebiasis while other two species Entamoeba dispar and Entamoeba moshkovskii are nonpathogenic. Life cycle of this E. histolytica includes trophozoite, precyst, cyst, metacyst, and metacystic trophozoite stages. Mature cysts have four nuclei and average 20 mm in diameter, while the motile form trophozoite has a size range of 10e60 mm. The cyst form is the infective form for humans, which can survive in water and food. Infections due to E. histolytica have been recorded globally and it is suggested that from the infected persons around 10% show clinical symptoms. According to literature except for the two parasites, plasmodia and schistosomes, most deaths have been assigned to E. histolytica than any other parasite. In developed countries, risk groups include travelers, immigrants, migrant workers, and immunocompromised individuals. Transmission of this protozoan by water is common in developing countries, where much of the water supply for drinking is untreated and fecally contaminated (Marshall et al., 1997). 2.4 Waterborne helminths The helminths, generally known as parasitic worms, are invertebrates with elongated, flat, or round bodies which belong to Kingdom Animalia. The major parasitic helminths include in the phylum Nematoda (roundworms) and the phylum Platyhelminthes (trematodes). Helminth parasites infect a large number of people and animals worldwide, mainly in developing countries due to lack of water, sanitation, and hygiene facilities. Dracunculus medinensis (Guinea worm) and Fasciola spp. (Fasciola hepatica and Fasciola gigantica) (liver flukes) are the major helminths which can be transmitted through drinking water.

30 Waterborne Pathogens

2.4.1 The genus Dracunculus The genus Dracunculus belongs to the phylum Nematoda and family Dracunculidae, which is parasite of mammals and reptiles. There are 14 valid species in this genus but D. medinensis has been well-studied because of human infections. Dracunculiasis or Guinea-worm disease (GWD) is an avoidable waterborne disease caused by the parasite D. medinensis which affect the populations in rural parts of South Asia and Africa. Reported cases worldwide annually have declined from an estimated 3.5 million cases in 1986 to only 28 cases in 2018 (WHO, 2019). GWD is now restricted to some communities in remote parts of Africa. Humans get exposed to the disease through consumption of drinking water containing Cyclops spp. carrying infectious D. medinensis larvae. After ingestion, larvae are released, penetrate the intestinal and peritoneal walls, and inhabit the subcutaneous tissues. 2.4.2 The genus Fasciola The genus Fasciola belongs to the phylum Platyhelminthes and family Fasciolidae, which causes fasciolosis in human and ruminants. The main pathogenic species are F. hepatica (temperate fluke) and F. gigantica (tropical fluke). It is estimated that more than 17 million people are infected worldwide and about 180 million people living in endemic areas are at risk to infection (Cwiklinski et al., 2016). Human infection generally occurs through consumption of aquatic vegetables such as watercress, drinking water contaminated with encysted cercariae, or washing utensils with contaminated water. The above-discussed and the most important waterborne pathogens belonging to the four categories bacteria, viruses, protozoa, and helminths, their diseases, and mode of transmission are summarized in Table 2.1.

3. Potential waterborne pathogens In 1997, WHO defined emerging pathogens as those that have appeared in a human population for the first time or have occurred previously but are increasing in incidence or expanding into geographical areas where they have not previously been reported. Reemerging pathogens are those whose occurrence is increasing as a result of long-term changes in their underlying epidemiology (WHO, 2003). By these criteria, 175 species of infectious agent from 96 different genera were classified as emerging pathogens in 1970s and from this group, 75% were zoonotic species. However, currently several of this microorganism from environmental sources, including water, have been confirmed as pathogens, including Cryptosporidium, Legionella, E. coli O157, RV, hepatitis E virus, and norovirus. H. pylori is an example of a recently emerged pathogen that may be transmitted through water (WHO, 2003).

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TABLE 2.1 The waterborne pathogens. Pathogen

Disease

Mode of transmission

Vibrio cholera, serovarieties O1 and O139

Cholera, gastroenteritis

Fecaleoral route

Salmonella sp.

Salmonellosis, gastroenteritis

Fecaleoral route

Shigella sp.

Shigellosis

Fecaleoral route

Escherichia coli, serotype O157:H7

Diarrhea, hemorrhagic colitis, hemolytic uremic syndrome

Fecaleoral route

Burkholderia pseudomallei

Melioidosis

Direct contact with contaminated soil and surface waters

Campylobacter sp.

Diarrhea, gastroenteritis

Consumption of contaminated food

Francisella tularensis

Tularemia

Arthropod bites, direct contact with infected animals, and inhalation or ingestion of contaminated water

Legionella pneumophila

Acute respiratory illness, pneumonia (legionellosis)

Inhalation of contaminated aerosols

Mycobacterium avium complex (MAC)

Pulmonary disease, skin infection

Inhalation of contaminated aerosols

Adenovirus

Gastroenteritis, respiratory, ocular, and urinary tract infections

Inhalation of contaminated aerosols, fecaleoral route

Astrovirus

Gastroenteritis, respiratory infections

Fecaleoral route

Norovirus

Gastroenteritis, diarrhea

Fecaleoral route

Sapoviruses

Acute viral gastroenteritis

Fecaleoral route

Hepatitis A and E viruses

Hepatitis

Fecaleoral route

Rotavirus

Diarrhea, gastroenteritis

Fecaleoral route

Bacteria

Viruses

Continued

32 Waterborne Pathogens

TABLE 2.1 The waterborne pathogens.dcont’d Pathogen

Disease

Mode of transmission

Cryptosporidium sp.

Cryptosporidiosis

Fecaleoral route

Giardia intestinalis

Giardiasis

Fecaleoral route

Entamoeba histolytica

Amebiasis

Fecaleoral transmission

Toxoplasma gondii

Toxoplasmosis

Ingestion of water contaminated with oocysts

Dracunculus medinensis

Dracunculiasis

Consumption of contaminated water

Fasciola hepatica, Fasciola gigantica

Fascioliasis

Consumption of aquatic plants with metacercariae

Protozoa

Helminths

3.1 Potential waterborne bacteria 3.1.1 Helicobacter pylori Bacteria of genus Helicobacter are Gram-negative, curved, or spiral-shaped belonging to the family Helicobacteraceae and class Epsilonproteobacteria. H. pylori is a helix-shaped bacterium, 3 mm long with a diameter about 0.5 mm. Genus Helicobacter contains more than 40 described species and 4 Candidatus species, a designation of provisional status by International Committee on Systematic Bacteriology for incompletely described prokaryotes, and is divided according to their major colonization sites as gastric or lower intestinal tracteassociated bacterial species. It is a genetically diverse gastric pathogen, carrying a range of antibiotic resistance patterns, and varies in geographic occurrence. These are considered as major etiologic agent for gastritis and are also connected to pathogenesis of peptic and duodenal ulcer disease and gastric carcinoma. But most individuals remain asymptomatic. Approximately 70% e90% of persons in developing countries and 25%e50% of those in developed countries are colonized by H. pylori and it is transmitted mainly by fecaleoral or oraleoral routes, with water and food as the sources (Doyle, 2012). Epidemiological studies have associated the H. pylori infection with lack of access to potable drinking water and proper sanitation H. pylori in drinking water biofilms, change their morphology, and persist for more than 1 month, with densities exceeding 106 cells/cm2 (Giao et al., 2008).

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3.1.2 Aeromonas hydrophila Aeromonas are straight, coccobacillary to bacillary, belonging to family Aeromonadaceae of order Aeromonadales who are nonespore-forming, facultative anaerobic, Gram-negative bacteria with cells having a size of 0.3e1.0  1.0e3.5 mm. Although Aeromonas hydrophila is usually the dominant species, other aeromonads, such as Aeromonas caviae and Aeromonas sobria, have also been isolated from human feces and water sources. A. hydrophila has been recognized as an opportunistic pathogen being identified as a potential agent of gastroenteritis, septicemia, meningitis, and in wound infections. It plays a significant role in intestinal disorders in children under 5 years old, the elderly, and immunosuppressed people. Ubiquitous in nature, it is frequently isolated from food, drinking water, and aquatic environments. In surface waters, mainly rivers and lakes, concentrations of Aeromonas spp. are high but groundwaters generally contain lesser numbers. Drinking water immediately leaving the treatment plant could contain between 0 and 102 CFU/mL and these waters can display higher Aeromonas concentrations, due to the growth in biofilms (Chauret et al., 2001). A. hydrophila is resistant to standard chlorine treatments and it is assumed that they survive by being within the biofilms. The common routes of infection are the ingestion of contaminated water or food or through skin. No person-to-person transmission has been reported. 3.1.3 The genus Leptospira The genus Leptospira belongs to family Leptospiraceae of the phylum Spirochaete and currently contains 20 species including 9 pathogenic, 6 saprophytic, and 5 being intermediate. They are thin, tightly coiled, motile spirochetes, generally 6e20 mm in length, but during culturing they may produce much longer cells. The surface structure of the Leptospira shows both Gram-negative and Gram-positive characteristics. The disease leptospirosis is one of the most widespread zoonotic diseases, infecting both human and animals caused by the Leptospira. The major route of exposure to the pathogen is indirect contact with contaminated water or moist soil. In developing countries from tropics, leptospirosis is an occupational infection, most affected being the people who are engaged in farming, sharecropping, and in animal husbandry (Levett, 2001). Furthermore, there is a significant risk of exposure during recreational activities. Leptospirosis is essentially waterborne infection, as several outbreaks of disease have been recorded during rainy season. Both pathogenic and saprophytic strains of leptospirosis have been isolated from water sources including rivers and lakes as they are able to survive in moist soil and freshwater for long periods of time (Pal and Hadush, 2017).

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3.1.4 The genus Tsukamurella Bacteria belonging to genus Tsukamurella of order Actinomycetales are Gram-positive, nonmotile, obligate aerobic, irregular, and rod-shaped. The genus includes 11 species and out of which 9 Tsukamurella species have been isolated from human infections. Most of Tsukamurella species exist as environmental saprophytes present in soil, arthropods, water, sludge foam, and sponges. Some species have been detected in drinking water supplies, but there is no evidence of correlation between the presence of organisms and the disease. They are opportunistic pathogens and can transmit through clinical instruments such as catheters or lesions. Tsukamurella cause various infections in humans, including pulmonary and cutaneous infections and meningitis and most vulnerable are immunocompromised individuals. 3.1.5 The genus Bacillus Bacteria belonging to genus Bacillus of phylum Firmicutes are rod-shaped, Gram-positive, strictly aerobic, or facultatively anaerobic and are capable of endospore formation. Bacillus species are commonly found in soil and water. They have been detected in drinking water supplies even after disinfection processes, but waterborne transmission is not yet confirmed. Only few Bacillus species are pathogenic to human. With Bacillus cereus causing bacteremia in immunocompromised patients, B. anthracis causes anthrax in humans and animals. In a study conducted by Taylor et al. (2005), strains of Bacillus megaterium, Bacillus firmus, Bacillus simplex, and B. cereus were found to produce heat-stable toxins, with varying levels of toxicity. 3.1.6 Cyanobacteria and cyanotoxins Cyanobacteria are a phylum with an estimated 150 genera of cyanobacteria containing approximately 2000 species, of which around 46 have been reported as being toxigenic. They are oxygenic, photosynthetic, Gram-negative bacteria that inhabit a large variety of terrestrial and aquatic habitats, showing a wide diversity in morphology and their average cell size ranges from 0.5 to 60 mm. In 1998, cyanobacteria were included as a microbial contaminant to CCL because of their potential for transmission through drinking water. Furthermore, microcystin-LR, cylindrospermopsin, and anatoxin-a produced by several species of cyanobacteria are also included in the CCL. These cyanotoxins have been reported from water reservoirs around the world which had caused acute and chronic illnesses in animals and humans (Liyanage et al., 2016). Exposure to cyanotoxins can be through contaminated drinking water, ingestion and dermal skin contact during recreational activities (Fig. 2.2), inhalation of aerosols, medical treatments (dialysis), or through algal food supplements.

Ubiquitous waterborne pathogens Chapter | 2

(A)

(B)

(C)

(D)

(E)

(F)

35

FIGURE 2.2 A lake in a developing country where people are engaged in recreational activities. (A) Lake Gregory, Sri Lanka; (B) recreational activity area; (C) people engaged in boat riding; potential toxic cyanobacteria; (D) Anabaena sp.; (E) Oscillatoria sp.; (F) Microcystis sp. (MaganaArachchi et al., 2011).

3.2 Potential waterborne viruses In 2017, GWPP reported 10 emerging viruses with potential for waterborne transmission including genera Alphatorquevirus, Cyclovirus, Erythroparvovirus, Bocaparvovirus, Protoparvovirus, Alphapapillomavirus, Betapapillomavirus, Picobirnavirus, Betapolyomavirus, and Alphapolyomavirus (Rusinol and Girones, 2017) (Table 2.2).

3.3 Potential waterborne protozoa 3.3.1 Microsporidia Microsporidia belonging to the phylum Microspora include over 140 genera and 1200 species that are parasitic in all major animal groups. They are obligate intracellular, spore-forming protists. The spore is the only stage that can survive outside the host cell in their life cycle and it contains a characteristic coiled polar filament for injecting the sporoplasm into a host cell to initiate infection. After infection, a complex process of multiplication takes place within an infected cell and new spores are produced and released to feces, urine, respiratory secretions, or other body fluids, depending on the type of species and the site of infection. Among 14 human pathogenic Microsporidia species, two species, Enterocytozoon bieneusi and Encephalitozoon

36 Waterborne Pathogens

TABLE 2.2 The potential waterborne pathogens. Pathogen

Disease

Mode of transmission

Helicobacter pylori

Gastritis, peptic and duodenal ulcer disease, and gastric carcinoma

Oraleoral or fecaleoral transmission

Aeromonas hydrophila

Gastroenteritis, septicemia, meningitis, and wound infections, intestinal disorders in children

Ingestion of contaminated water or food, through skin

Leptospira sp.

Leptospirosis

Through water contaminated by urine from infected animals

Tsukamurella sp.

Pulmonary and cutaneous infections, meningitis

Through clinical instruments such as catheters or lesions

Bacillus sp.

Diarrhea

Through drinking water

Cyanobacteria and cyanotoxins

Gastrointestinal symptoms, skin rashes, kidney disease

Through drinking water, bathing in contaminated water

Alphatorquevirus

Asymptomatic. May be associated with hepatitis, pulmonary diseases, hematologic disorders, myopathy, and lupus

Fecaleoral route

Cyclovirus

Systemic infections may play a role in development of paraplegia

Fecaleoral and foodborne transmission

Erythroparvovirus

Fifth disease in children, arthropathy, hepatitis

Respiratory route

Bocaparvovirus

Gastroenteritis, related to respiratory infections

Respiratory and fecaleoral routes

Protoparvovirus

Gastroenteritis

Respiratory and fecaleoral routes

Alphapapillomavirus

Cervix, penis, anus, and vulva cancers

Direct skin-to-skin or skin-tomucosa contact

Betapapillomavirus

Related to genital warts

Direct skin-to-skin or skin-tomucosa contact

Picobirnavirus

May be implicated in gastroenteritis

Fecaleoral route

Betapolyomavirus

Progressive multifocal encephalopathy

Fecaleoral route

Bacteria

Virusesa

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TABLE 2.2 The potential waterborne pathogens.dcont’d Pathogen

Disease

Mode of transmission

Alphapolyomavirus

Associated to Merkel cell carcinoma

Fecaleoral route

Microsporidia

Microsporidiosis

Fecaleoral transmission

Cyclospora cayetanensis

Diarrheal illness, gastroenteritis

Fecaleoral transmission

Cystoisospora belli

Cystoisosporiasis

Fecaleoral transmission

Schistosomiasis, liver and kidney damage

Penetrate the skin during contact with infested water

Protozoa

Helminths Schistosoma sp.

a Adapted from Table 2.2 in summary of excreted and waterborne viruses (Rusinol and Girones, 2017).

intestinalis, are the most prevalent species which associated with gastrointestinal disease in humans. Person-to-person contact and ingestion of spores in water and food contaminated with human feces or urine are considered as important routes of exposure. A study by Dowd et al. (1998) showed that 7 out of 14 water concentrates tested were contaminated with E. intestinalis, E. bieneusi, and Vittaforma corneae which represent human pathogenic microsporidia species. Their study is the first species level confirmation of human pathogenic microsporidia in water, indicating that these human pathogenic microsporidia possibly be waterborne pathogens. Microsporidiosis is an emerging disease in immunosuppressed persons with AIDS, but microsporidia have the ability to cause disease even in immunologically normal hosts.

3.3.2 Cystoisospora belli Cystoisospora (formerly Isospora) are coccidian parasites, belonging to the phylum Apicomplexa, found mainly in tropical and subtropical areas. Many Cystoisospora species can infect animals, but human is the only known host for C. belli (Lindsay et al., 1997). C. belli infects the epithelial cells of the small intestine of human, and immunocompromised individuals are more susceptible to the infection. The immature form of the parasite is known as oocytes; they are passed out with feces and then mature outside the body in 2e3 days, depending on environmental conditions. It can be transmitted

38 Waterborne Pathogens

through contaminated water and food. However, direct person-to-person transmission is unlikely. The improved practice of personal hygiene and sanitation may help in preventing transmission of disease.

3.3.3 Cyclospora cayetanensis Cyclospora cayetanensis belongs to the family Eimeriidae, 7.5e10 mm in diameter, cyst-forming, and unsporulated when passed in feces. It is an apicomplexa coccidia closely related to Eimeria species, recognized as an emerging protist that causes diarrheal illness and significantly contributes to the burden of gastroenteritis worldwide. 3.4 Potential waterborne helminths 3.4.1 The genus Schistosoma Schistosomes are trematode parasites which cause schistosomiasis (or bilharzia) in human. The main human pathogenic species are Schistosoma mansoni, Schistosoma japonicum, and Schistosoma haematobium. Schistosomiasis is a waterborne disease mostly seen in the tropics and subtropics. The humans get exposed when their skin comes into contact with infested freshwater, into which the cercariae of the parasite are released by freshwater snails. It is understood that for each of the human schistosomes, the presence of a specific genus of snail is necessary for transmission to occur. This disease has been considered as a disease due to poverty, and controlling of this disease has been a problem because of the lack of clean water available to people living in the developing countries. The most important potential waterborne pathogens as described by WHO belonging to the four categories bacteria, viruses, protozoa, and helminths, their diseases, and mode of transmission are summarized in Table 2.2.

4. Summary This chapter provides a general description on current waterborne pathogens as well as emerging and potential pathogens which could be categorized into bacteria, viruses, protozoans, and helminths. Most of these microorganisms are ubiquitous in waters regardless of ground, surface, fresh, or marine. People utilize these waters for drinking, cooking, and other domestic actions, bathing, medically, and also for recreations. The water sources become polluted due to the mixing of fecal matter from human and animal and also waste generated by other direct and indirect anthropogenic activities. As a result, waters become reservoirs for the pathogens making it unsafe for human consumption causing many waterborne diseases. In addition, with the increase in global population, changes in climatic patterns, and the presence of antibiotic resistant bacteria in waste waters, it is predicted that there will be a rise in waterborne diseases

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especially diarrhea and cholera. Therefore, still the global populations infants, young, or old are at a risk from waterborne diseases and outbreaks whether the countries are developed or developing or in tropics or temperate in geographical distribution. Hence to minimize the adverse effects from these waterborne pathogens and to improve the water quality, regular monitoring of water sources is essential with advanced but cost-effective detection techniques, precise disinfectant procedures with proper management.

Acknowledgment We are expressing our sincere gratitude to Ms. Chanusha Weralupitiya for technical support in preparation of Fig. 2.1.

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Maunula, L., Miettinen, T., Von Bonsdorff, H., 2005. Norovirus outbreaks from drinking water. Emerg. Infect. Dis. 11 (11), 1716e1721. Murray, J., Vos, T., Lozano, R., Naghavi, M., Flaxman, D., Michaud, C., Ezzati, M., Shibuya, K., Salomon, A., Abdalla, S., Aboyans, V., 2012. Disability-adjusted life years (DALYs) for 291 diseases and injuries in 21 regions, 1990e2010: a systematic analysis for the global burden of disease study 2010. Lancet 380 (9859), 2197e2223. Pager, T., Steele, D., 2002. Astrovirus-associated diarrhea in South African adults. Clin. Infect. Dis. 35 (11), 1452e1453. Pal, M., Hadush, A., 2017. Leptospirosis: an infectious emerging waterborne zoonosis of global significance. Air Water Borne Dis. 6, 1e4. Patel, C., Shanker, R., Gupta, V., Upadhyay, R., 2016. Q-PCR based culture-independent enumeration and detection of Enterobacter: an emerging environmental human pathogen in riverine systems and potable water. Front. Microbiol. 7, 172. Rusinol, M., Girones, R., 2017. Summary of excreted and waterborne viruses. In: Rose, J.B., Jime´nez-Cisneros, B. (Eds.), Global Water Pathogen Project (GWPP). Michigan State University, E. Lansing, MI. UNESCO. Schaub, S., Oshiro, R., 2000. Public health concerns about Caliciviruses as waterborne contaminants. J. Infect. Dis. 181 (s2), S374eS380. Taylor, J.M., Sutherland, A.D., Aidoo, K.E., Logan, N.A., 2005. Heat-stable toxin production by strains of Bacillus cereus, Bacillus firmus, Bacillus megaterium, Bacillus simplex and Bacillus licheniformis. FEMS Microbiol. Lett. 242 (2), 313e317. United Nations General Assembly (UNGA), 2010. The Human Right to Water and Sanitation: Resolution/Adopted by the General Assembly. UNSD, 2015. Transforming Our World: The 2030 Agenda for Sustainable Development. United Nations General Assembly Resolution (UNSD). A/RES/70/1. Walker, F., Rudan, I., Liu, L., Nair, H., Theodoratou, E., Bhutta, A., O’Brien, L., Campbell, H., Black, E., 2013. Global burden of childhood pneumonia and diarrhoea. Lancet 381 (9875), 1405e1416. Wang, H., Liddell, A., Coates, M., Mooney, D., Levitz, E., Schumacher, E., Murray, C.J., et al., 2014. Global, regional, and national levels of neonatal, infant, and under-5 mortality during 1990e2013: a systematic analysis for the global burden of disease study 2013. Lancet (Lond Engl) 384 (9947), 957e979. Wasey, A., Salen, P., 2019. Escherichia coli (E. coli 0157 H7) (Updated 2019 Feb 3). In: StatPearls [Internet]. StatPearls Publishing, Treasure Island, FL. Available from: https://www.ncbi.nlm. nih.gov/books/NBK507845/. Weintraub, A., 2003. Immunology of bacterial polysaccharide antigens. Carbohydr. Res. 338 (23), 2539e2547. WHO, UNICEF, 2017. Progress on Drinking Water, Sanitation and Hygiene: Update and Sustainable Development Goal Baselines. World Health Organization (WHO) and the United Nations Children’s Fund (UNICEF), Geneva. License: CC BY-NC-SA 3.0 IGO. WHO, UNICEF, World Bank, 2009. State of the World’s Vaccines and Immunization, third ed. Geneva. Wiersinga, J., Virk, S., Torres, G., Currie, J., Peacock, J., Dance, A., Limmathurotsakul, D., 2018. Melioidosis. Nat. Rev. Dis. Prim. 4, 17107. World Health Organization, 1997. Division of Emerging and Communicable Diseases Surveillance and Control Annual Report- 1996. World Health Organization, 2003. Emerging Issues in Water and Infectious Disease.

42 Waterborne Pathogens World Health Organization, 2011. Guidelines for Drinking-Water Quality, fourth ed. WHO Press, Geneva, Switzerland. World Health Organization, 2012. WHO position paper on hepatitis A vaccines-June 2012. Wkly. Epidemiol. Rec. 87 (28e29), 261e276. World Health Organization, 2019. Dracunculiasis (Guinea-Worm Disease) Fact Sheet. Yu, L., Plouffe, F., Pastoris, C., Stout, E., Schousboe, M., Widmer, A., Summersgill, J., File, T., Heath, M., Paterson, L., Chereshsky, A., 2002. Distribution of Legionella species and serogroups isolated by culture in patients with sporadic community-acquired legionellosis: an international collaborative survey. J. Infect. Dis. 186 (1), 127e128.

Chapter 3

Waterborne pathogens: review of outbreaks in developing nations Md. Sirajul Islam, Md. Hassan-uz-Zaman, Md. Shafiqul Islam, John David Clemens, Niyaz Ahmed International Centre for Diarrhoeal Disease Research, Bangladesh (icddr,b), Dhaka, Bangladesh

1. Introduction Waterborne pathogen outbreaks, while displaying commonality in broad modes of transmission, differ significantly in terms of scope, effect, and etiologies between the developed and developing parts of the world. Owing to advancements in water, sanitation, and hygiene infrastructure and practice, these outbreaks have become much less common in the developed countries (Craun, 2012). The most important recent pathogens implicated in outbreaks in developed countries include parasites like Giardia and the bacteria Legionella. In a systematic review of waterborne pathogen outbreaks in the United States between 1971 and 2008, 18% of the outbreaks with discernible etiologies were caused by parasites, mostly Giardia (Craun, 2012). With a global prevalence of roughly 30%, it has been estimated to be present in 3% e7% of the US population (Spiteri et al., 2015). The disease, giardiasis, is a self-limiting disease which is nonsymptomatic in 10% of the cases. Symptoms commonly include diarrhea, abdominal pain, and weight loss and may last for up to 6 weeks if left untreated. Giardiasis is transmitted due to the ingestion of parasite cysts via the fecaleoral route (Barry et al., 2013). Consumption of contaminated water is the most important risk factor, as the cysts can retain their infectious nature for up to 6 months in cold water. According to the Center for Disease Control (CDC), risk factors for contracting the disease significantly include swallowing contaminated water from ponds by backpackers or campers (Kramer et al., 1996). This is reinforced by the fact that giardiasis outbreaks in the United States peaks during summer, presumably because of the greater amount of time spent on outdoor activities (Bashir et al., 2016; Auerbach, 2011). Legionella continues to be responsible for 7% of the Waterborne Pathogens. https://doi.org/10.1016/B978-0-12-818783-8.00003-7 Copyright © 2020 Elsevier Ltd. All rights reserved.

43

44 Waterborne Pathogens

waterborne disease outbreaks with known etiologies, and it has seen a sharp spike in proportion in the 2000e08 period (Craun, 2012). The pathogen is found throughout the world in both natural and man-made aquatic systems, and its most prevalent type of transmission is inhalation of contaminated aerosol. This causes the infection of alveolar macrophages by the bacteria, which can results in both Legionnaires’ disease and Pontiac fever. This mode of transmission usually implicates artificial water systems like air conditioning cooling towers, humidifiers, and hot tub spas (Correia et al., 2016). The theme that emerges from this brief survey of these two pathogens mostly implicated in waterborne pathogen outbreaks in the developed world goes to show that ingestion of contaminated water, in the form of swallowing or taking in contaminant-bearing aerosol, is mostly responsible for these outbreaks in the developed world. The outbreaks in the developing countries, on the other hand, constitute a much more complex phenomenon and would constitute the focus of the paper as diarrheal diseases and cholera as primary case studies.

2. Waterborne pathogen outbreaks in developing countries In her widely cited paper, Rita Colwell emphasized the association between cholera outbreaks and the coastal environmental drivers (Colwell, 1996). This has been reinforced by a number of subsequent studies attempting to link cholera to its environmental drivers, notably sea surface temperature, sea surface height, and ocean chlorophyll concentration. A number of mathematical models have also been constructed to predict ensuing cholera outbreaks based on coastal environmental data (Emch et al., 2008; Baracchini et al., 2017; De Magny et al., 2008; Jutla et al., 2013). De Magny et al. (2008), for example, found significant associations between ocean chlorophyll concentrations and cholera cases in Matlab, Bangladesh, and Kolkata, India. Interestingly, in the case of Matlab, coastal phytoplankton was found associated with cholera outbreaks 1 month later. This was unlike the case on Kolkata, where monthly outbreak data were found to be associated with ocean phytoplankton measurements in the same month. This discrepancy has been explained by the authors as the relatively greater distance of Matlab from the sea. This and a number of similar associations reported in other studies have implicated coastal environmental drivers as a significant determinant of cholera outbreaks (De Magny et al., 2008). The assumption underlying these “coastal” models of cholera outbreaks seems to be that cholera, driven by ocean phytoplankton, strikes at the coast first, acting as the point-of-entry inland. While forming an essential part of cholera epidemiology, this view needs to be complemented by other considerations as well. In a systematic review of all reported cholera outbreaks in Africa from 1970 to 2012, the authors conclude that at least 76% of all cases of

Waterborne pathogens: review of outbreaks in developing nations Chapter | 3

45

cholera in sub-Saharan Africa affected inland (or noncoastal) communities (Rebaudet et al., 2013). A complete view of cholera epidemiology would need to provide explanations for such inland outbreaks as well. Another significant caveat in the cholera paradigm, related to the first one, is that the coastal view of cholera epidemics may fail to accommodate the role of local domestic surface water reservoirs in cholera spread. In the same study above concerning cholera in inland Africa, the authors note that most of these cases of cholera have been clustered in two locations with a high population density and a high concentration of lakes. In a study analyzing multidecadal cholera data in rural Bangladesh, the authors also reported a significant association between cholera and surface water use. Proximity to the lakes was a significant risk factor for cholera in several ecological studies (Shapiro et al., 1999; Bompangue et al., 2008, 2009; Birmingham et al., 1997). The mechanistic explanation for this association has been described in another chapter of this book. Many of these epidemiologically significant surface waterbodies tend to be closed water systemsdmeaning that they have less of an opportunity to receive input from rivers, with the possible occasional exception of inundation during seasons of flooding. As such, the association between use of surface water from local domestic water reservoirs and cholera outbreaks is to be explained in terms of these reservoirs acting as standalone reservoirs of pathogen, independent of coastal input. A curious fact about the cholera epidemiology in Bengal serves to substantiate this fact. During seasons of cholera epidemic, it has been observed that the outbreaks do not primarily spread from a single point of entry, rather widely separated villages experience outbreaks at the same time (Glass et al., 1982). This feature can only be explained by positing the local, domestically used closed ponds and lakes acting as self-contained reservoirs of the cholera bacteria. The seasonality of these outbreaks is regulated by certain local environmental factors, as discussed in another chapter of this book.

3. WASH and waterborne disease outbreaks Poor water, sanitation, and hygiene situations are important risk factors for outbreaks of cholera and other diarrheal diseaseda connection known since the birth of modern epidemiology at the hands of John Snow. Perhaps the most prominent case in point here is global refugee crises. Situations involving massive population displacement, especially refugee crises, are widely implicated as triggering cholera outbreaks. The amplification of risk of cholera in refugee settings is primarily due to the poor water and sanitation facilities. According to the estimations of a 2008 report, more than half of the global refugee camps did not provide the recommended daily water requirement (20 L) to each individual (Phares and Ortega, 2014). In addition, 30% of the camps did not have adequate latrine facilities. The region in Africa where the majority of inland cholera cases have been clustered is characterized by many

46 Waterborne Pathogens

refugee camps. This, in addition to the preponderance of concentrated closed surface water reservoirs, acted synergistically to amplify both the environmental and infrastructure-related risk of cholera. Water and sanitation interventions are often difficult to administer in these settings, for a number of reasons having to do with the “political, financial, social, and national security” factors of the host countries (Phares and Ortega, 2014). The situation in Africa is complicated even further when cholera outbreaks occurred in association with droughts (Tauxe et al., 1988). Reinforcing the theme of the environment-WASH multidimensionality of cholera outbreaks, Reiner et al. (2012) investigated the spread of cholera epidemics in urban Dhaka. They found that while large-scale climatic events like the El Nino are closely associated with cholera outbreaks, these effects are mediated through the way the city is spatially structured in terms of its population density and water and sanitation infrastructure. The authors found there’s a climate-sensitive “core” collection of administrative units in the city which mediate the advancing front of cholera outbreaks (initially triggered by El Nino) to the rest of the city, and this “core” is characterized with extremely high population density and poor water, sanitation, and hygiene conditions.

4. Water quality: contribution to disease While the important role of poor water quality in the outbreak of cholera and other diarrheal diseases is known, there remains ambiguity about the extent of this contribution when it interacts with other sociodemographic factors. Cholera and diarrheal diseases in general are multidimensional and have a wide range of correlates having to do with biology, sociology, and the environment. Considerable ambiguity also remains as far as the modality of appropriate intervention measures are concerned. The Sustainable Development Goals (SDG), for example, include ensuring “availability and sustainable management of water and sanitation for all” by 2030 as its sixth goal, subsuming “universal and affordable access to safe and affordable drinking water for all” among the primary targets (Ajiero and Campbell, 2018). Taking Bangladesh as a case study in this regard, the country has seen significant improvements as far as access to improved water sources is concerned. According to the UNICEF Multiple Indicator Cluster Survey 2012e13 report (Pozo et al., 2015), 97.1% of the population has access to an improved water source. However, the mere access to an improved water source does not faithfully portray household water quality. Indeed, the same report cites 41.7% of the population using source water with at least medium risk (i.e., at least 1 Escherichia coli per 100 mL), while 61.7% of point-of-use samples had the same contamination profile. This is reflected at the level of diarrheal disease epidemiology in Bangladesh: in a comprehensive study of morbidity and mortality data from district-level hospitals in Bangladesh, the authors report diarrhea as still being the leading cause of morbidity, despite “advances in health technology, improved management, and increased use of

Waterborne pathogens: review of outbreaks in developing nations Chapter | 3

47

oral rehydration therapy” (Sultana et al., 2015). It is interesting to note that the country shows the opposite trend as that of a developing country. In a survey of the trends of waterborne pathogen outbreaks over a period of 37 years in the United States, contamination at the point of use has been implicated in only 1% of the outbreaks. This is in stark contrast to the high proportion of household water contaminated at the point of use in Bangladesh. Furthermore, there is ambiguity in the literature as far as the extent of the contribution of water quality to diarrheal diseases is concerned. According to a WHO water sanitation and hygiene fact sheet (Water, Sanitation, and World Health Organization, 2004), 88% of diarrheal diseases can be attributed to unsafe water supply, inadequate sanitation, and hygiene. However, more recent reviews suggest less drastic numbers. In 2010, unimproved water and sanitation was responsible for 0.9% of disease-adjusted life years (Engell and Lim, 2013). Despite differences in extent among the studies, the authors unequivocally reported a significant effect of both improved water and sanitation on diarrheal morbidity. These conclusions have been bolstered by metaanalyses on the effect of WASH on diarrheal incidence conducted in low- and middleincome settings (Wolf et al., 2014). On the other hand, another report found the presence and extent of association between diarrheal incidence and water quality to significantly depend on the choice of indicator bacteria (Vannavong et al., 2018). Taken together, these studies suggest that while there are significant associations between diarrheal morbidity and water quality, these associations can be difficult to establish (Levy, 2015). This ambiguity has been attributed to a number of factors, including the imperfect correlation between indicator bacteria and presence of enteric pathogens in water (Wu et al., 2011a,b) and high levels of variability in household water quality (Levy et al., 2009). However, these constraints can be overcome by careful study design (e.g., by accounting for the incubation period of pathogens during diarrheal surveys), multiple rounds of sampling, and a large sample size. Indeed, a study covering 50 villages in Bangladesh found an association between childhood diarrheal morbidity and water quality measured by E. coli and estimated the population-attributable fraction of diarrhea due to contaminated water to be at least 17% (Luby et al., 2015). Given such a figure, it is not surprising that studies with anything less than very high statistical power would pick on this correlation. In their discussion of the results, the authors list several factors that may explain the apparent weakness of correlation between water quality and waterborne diseases reported in some studies: indicator bacteria only weakly approximating contamination by enteric pathogens; host immunity to circulating pathogens; weak approximation of actual water quality (which is highly variable) with measured water quality; and in the case of drinking water intervention studies, the participants possibly underreporting diarrhea out of courtesy. These factors together provide an explanation for the apparent imperfect correlation.

48 Waterborne Pathogens

5. Groundwater quality The question of water quality brings its own problems when it comes to groundwater. In many developing countries like Bangladesh, groundwater sources substantially address the domestic demand of potable water. While generally this is of a better quality than surface water, it has the drawback of being complicated and costly to treat once it becomes contaminated. When considering its implications in waterborne disease outbreak, it is therefore imperative to understand precisely the modes and mechanisms of groundwater contamination. One particularly complicating variable in this regard is sanitationdmore specifically, liquid effluent from on-site excreta disposal systems like pit latrines. Among different options of on-site sanitation, pit latrines are in general the cheapest form of sanitation and can be easily constructed at a household level. In rural areas of many developing countries and refugee crisis situations, they often represent the only viable sanitation option given the low level of water supply service. Given this fact, many would see pit latrines as the main modality of widespread sanitation coverage in the rural developing world. However, concerns have been raised about pit latrines potentially increasing pollution of groundwater. It has been predicted, for example, that achieving 100% latrine coverage will result in a 1.9e4.1 times increase in protozoan contamination of groundwater sources (Daniels et al., 2016). Other researchers have also raised this concern (Odagiri et al., 2016; Sorensen et al., 2016). The pathogens from the pit latrine may infiltrate through the ground (unsaturated and saturated) and ultimately reach the groundwater (Lewis et al., 1980). It has been found that shallow groundwater at depths of 50 m below the surface gets contaminated with E. coli concentrations as high as 106/100 mL (Foppen et al., 2008). In a study in Bangladesh, it was also found that use of water from shallow tubewells is associated with more childhood diarrhea compared with deep tubewells (Wu et al., 2011a,b). Realistically, suggestion of a “general” guideline as regard the safe distance between a pit latrine and nearby aquifers is prima facie problematic. Groundwater vulnerability as a concept is plausibly understood as contextspecific, depending on its intrinsic vulnerability due to hydrogeological factors and extrinsic vulnerability due to the extent and nature of excreta disposal. In a 1-year study in 2008 in different physiographic units in Bangladesh, the extent of contamination of nearby aquifers by pit latrine leaching was investigated by strategically establishing “monitoring wells” of varying depths and distances around existing pit latrines and monitoring water quality at prespecified distances from the pit. The bacteriological contamination data were adjusted with the specific hydrogeological characteristics of study locations, including formation of aquifer sediments, soil properties, soil filtering capacity, depth of groundwater table, and flow direction. Microbiological contamination of water samples of monitoring wells and nearest existing tubewells in three sites and two seasons is presented in Table 3.1.

Well no.

Depth of well (m)

Distance of pit (m)

FC/ 100 mL

FS/ 100 mL

FC/ 100 mL

Wet season

FS/ 100 mL

FC/ 100 mL

Midterm

FS/ 100 mL

Dry season

Manda M-1

18.0

2.0

8

2

10

77

0

0

M-2

18.0

4.5

2

0

4

0

0

0

M-3

18.0

7.0

0

0

0

0

0

0

M-4

18.0

9.0

0

0

0

0

0

0

M-5

21.0

2.0

5

1

2

0

3

6

M-6

18.0

2.0

17

6

12

0

0

1

M-7

40.5

2.0

0

0

0

2

4

2

M-8

40.5

4.5

0

0

0

0

0

0

N

18.0

9.0

0

0

0

0

0

0

M-1

31.0

2.0

0

2

0

0

8

10

M-2

47.0

2.0

0

0

0

0

0

0

M-3

31.0

4.5

0

0

0

0

0

0

Mohanpur

49

Continued

Waterborne pathogens: review of outbreaks in developing nations Chapter | 3

TABLE 3.1 Microbiological contamination of water samples of monitoring wells and nearest existing tubewell.

Well no.

Depth of well (m)

Distance of pit (m)

FC/ 100 mL

FS/ 100 mL

FC/ 100 mL

Wet season

FS/ 100 mL

FC/ 100 mL

Midterm

FS/ 100 mL

Dry season

M-4

31.0

7.0

0

0

0

0

0

0

N

39.6

15.0

0

0

0

0

0

0

M-1

27.5

2.0

2

68

2

2

1

0

M-2

27.5

2.0

4

3

1

0

0

0

M-3

27.5

2.0

1

2

0

1

1

1

M-4

42.5

2.0

0

0

1

60

11

0

M-5

42.5

4.5

0

0

0

0

0

0

M-6

27.5

4.5

0

0

0

0

0

0

M-7

27.5

7.0

0

0

0

0

0

0

M-8

27.5

9.0

0

0

0

0

0

0

N

27.5

8.5

0

0

0

0

0

0

Bagmara

50 Waterborne Pathogens

TABLE 3.1 Microbiological contamination of water samples of monitoring wells and nearest existing tubewell.dcont’d

Waterborne pathogens: review of outbreaks in developing nations Chapter | 3

51

As hypothesized, the study showed that the safe distance of an aquifer to nearby pit latrine is very much dependent on the hydrogeological conditions of a particular area (Islam et al., 2016). In a follow-up of the study, evidence was found to the effect that the extent of contamination (both bacteriological and chemical) of groundwater due to latrine discharge has been generally exaggerated in popular imagination (Ravenscroft et al., 2017). More specifically, they estimated that 29% of the contamination to household drinking water is the tubewell pump system. In other words, it would be incorrect to equate the quality of the water collected from tubewell to contamination at the aquifer. This brings up the question of the origin of contamination in the collected water. Several studies have attributed the contamination to a broken or absent well base (Knappett et al., 2012), priming with contaminated water, or the hand pump itself being contaminated. A recent study in Bangladesh found high levels of fecal indicator bacteria in the tubewell spout and seal (Osborne et al., 2018). As corollaries to this research, the authors concluded that leakage from pit latrines is a relatively minor contributor to fecal contamination of drinking water and that fears of increased groundwater contamination should not constrain expanded latrine coverage, and more attention should be given to reducing contamination around the wellhead and at the point of use.

6. Intervention efforts Breaking these routes of transmission of waterborne pathogens would require interventions aimed at decontaminating surface water used at households, as well as modifying hygiene behavior. Multiple studies have reported a significant impact of water treatment and hygiene interventions on the transmission of cholera and other diarrheal diseases. In Bangladesh, for example, hand washing and water treatment interventions resulted in a 47% reduction in cholera incidence among household contacts in a hospital-based urban study (George et al., 2016). This is significant particularly because in choleraendemic regions, spread of cholera among household contacts from an initial index case is a common route of transmission (Sugimoto et al., 2014). Other significant intervention efforts notably include the simple filtration method introduced by Colwell et al. (2003). This method involved use of folded saris, traditional clothing worn by women in Bangladesh, as a filter to remove planktons and particulates >20 mm from water before use. The study conducted in 65 rural villages in Bangladesh (with a population of 133,000) led to a 48% reduction in cholera. It is the success afforded by this last instance of water treatment intervention that led to the development of a novel and more ambitious approach. In a more recent pair of publications, the development of a particularly cheap novel mixture (Siraj Mixture) for treatment of surface water based on principles of chemical treatment was reported (Islam et al., 2011). Fig. 3.1 shows the difference of surface water before and after treating with the novel mixture.

52 Waterborne Pathogens

FIGURE 3.1 Beakers containing raw water (left) and mixture treated water (right).

The mixture consists of three commonly used disinfectantsdalum potash, which acts to coagulate and settle the biological material; bleaching powder, which acts as a chlorinating agent; and lime, which restores the pH of the water to normal levels, rendering it palatable. Laboratory spiking experiments have demonstrated that the mixture can completely disinfect surface water samples with very high load of Vibrio cholerae and other bacteria (Table 3.2). The mixture was also tested with water samples collected from various surfaced water systems in a diarrhea-endemic area in Bangladesh. It was found that the mixture can treat various contaminated surface waters while also maintaining levels of various physicochemical parameters of the water within limits (Table 3.3) deemed acceptable by the WHO (Islam et al., 2011).

TABLE 3.2 Efficacy of the mixture in treating microbiologically contaminated pond water with inoculated Vibrio cholerae. Parameters

Before treatment

After treatment

TBC/mL

1.23  10

150

0.2 df

(5.1)

where dp is the diameter of particles retained and df is the diameter of filter bed grain (pore). l sedimentation, to which particles with a diameter of 2e10 mm and density of 2.6 g/cm3 (or respectively larger) are subjected. This process takes place both in the volume of water above the bed surface and in the intergranular spaces. l diffusion, which is determined by viscosities affecting particles with a diameter below 1 mm, i.e., not subject to a sedimentation process. l orthokinetic flocculation resulting in agglomeration of particles in the pores of the filter bed (the porosity of the deposit decreases) l catalytic and electrostatic interactions l adhesion (adhesion) and cohesion (cohesion) (b) chemical induced by the course of chemical reactions between the pollutant molecules and the filter bed. (c) biochemical associated with the occurrence and development of microorganisms in the filter bed in which contaminants are a substrate for nutrients and the resulting “biological membrane” contributes to the retention of biochemical decomposition of organic compounds and the retention of very fine suspensions (Janosz-Rajczyk, 2003).

Treatment of waterborne pathogens by microfiltration Chapter | 5

89

A special type of filtration, classified as a low-pressure membrane process, is a process called microfiltration (MF). The main mechanism for the particles through the membranes is the physical strain of more than pores (stage 1). The layer formed from retained contaminants on the surface of the membrane and in its pores is the so-called cake filtration (stage 2). The third mechanism of removal is the phenomenon of particle adsorption. Adsorption is caused by the affinity of membrane material and substances present in the solution (Gray, 2014; Bodzek et al., 1997; Bodzek and Konieczny, 2005; Wang et al., 2011). Adsorption sites are rapidly exhausted and so only occur immediately after backwashing, but it is an important interim mechanism while the solids cake develops on the surface. Adsorption is also a major cause of fouling which will eventually require the membrane unit to be removed and manually cleaned (Gray, 2014). These stages of the mechanism for removing particles through the membrane are presented in Fig. 5.3. This technology uses a membrane as an element that retains the solid parts of the stream with dimensions larger than the porosity of the membrane. The flow of liquid on the surface of the membrane can be guided in a parallel or perpendicular manner to its surface (Fig. 5.4). In the case of cross-processing, the feed is divided into two streams: permeate and retentate. Table 5.2 presents the advantages and disadvantages of conducting the MF process as in-line and cross-flow. The most important difference between MF and conventional filtration is the type of furniture used, its structure, and, consequently, the type of driving force of the cleaning process. Compared with conventional concentration processes, MF appears to be a good alternative for minimizing the adverse effects of heat. In general, filtration processes do not involve phase changes or high temperatures, thus favoring the maintenance of the sensory and nutritional characteristics of the product. The difference in hydrostatic pressure on both sides of the membrane, called the transmembrane pressure, is within the range of 0.05e0.5 MPa (in MF) to 1e10 MPa (in reverse osmosis [RE]). These methods allow the separation of various types of solutions (proper solutions, colloids, suspensions). Using the MF process, the following are removed from the solution: small suspensions, bacterial cells, some viruses, particles of vegetable raw materials, fat particles in emulsions (e.g., milk); the pressures used in the MF are of the order of 0.01e0.1 MPa, diameter pores in the membrane range from 0.1 to 10 mm (Kruithof et al., 1998; Hassan et al., 2013; Ahmad and Ismal, 2001) (Table 5.3). Depending on the type of contaminants to be retained in the water treatment process, the appropriate type of membrane should be used for the material and pore size. The type of membrane also affects the mechanism of pollution: strain (sieve mechanism) in the case of MF, ultrafiltration (UF), and dissolution and diffusion in the process of RE and nanofiltration (NF). Materials that form membranes in organic MF systems (polymeric materials) or inorganic materials (ceramics, vitreous, and metallic materials) are selected

90 Waterborne Pathogens

FIGURE 5.3 The main removal mechanism of particles by membrane (Gray, 2014).

Treatment of waterborne pathogens by microfiltration Chapter | 5

91

FIGURE 5.4 Schematic representation of in-line and cross-flow filtration with microfiltration membranes (Baker, 2004).

TABLE 5.2 Comparison of advantages and disadvantages of kind of microfiltration (Drioli and Giorno, 2015). In-line filtration

l l l l

l

Cross-flow filtration

l l

l

l

l

Low cost Simple operation Membrane must be replaced after each process The costs of membrane increase with the concentration of particles in the feed solution Suitable for dilute solution High cost Complicated operation filters require regular cleaning Membrane must be regularly cleaned to extend lifetimes The costs of membrane are independent of particle concentration Suitable for solutions with high concentration of particles

depending on the type of contaminants to be removed or the type of application. Membrane configurations include solutions such as hollow fiber, tubular, flat sheets, and spirals wound.

1.2.1 Advantages and disadvantages of conventional filtration for waterborne pathogens removal The filtration process has been known for a long time and is used in water purification. The earliest reports on the use of this process in water purification date back to 3000 years ago (India). The first filtration water treatment plant was built in 1804 in Paisley (Scotland, Great Britain). The concept of a slow filter was proposed by James Simpson in 1827 and has been successfully

Process

Pressure range [MPa]

Microfiltration

0.1e0.3

Ultrafiltration

0.3e1.0

Nanofiltration

0.5e3.0

Reverse osmosis

2.0e5.0

Membrane

Characteristics

Ceramics, polymers

Ceramic membranes, such as zirconium oxides, titanium oxides, aluminum oxides, have good chemical and physical stability in the pH range of 0.5e13 and operation up to 125 C; ceramic materials are not resistant to changes in temperature or pressure

Polymers

Polymers: polyvinyldeneflouride and polyethersulfonedthey are in the form of flat sheets, tubes, and spirals; these membranes are sensitive to high pressures (1.4 bar) and cross-system operation because of their low strength properties

Pore diameter

Separation mechanism

0.05e10 mm

Sieve separation

0.001 e0.05 mm

1e8 nm

Sieve separation, diffusion

Solid

Diffusion, dissolution

92 Waterborne Pathogens

TABLE 5.3 Division of membrane-forming materials depending on the membrane process used (Bodzek et al., 1997; Bodzek and Konieczny, 2005; Wang et al., 2011).

Treatment of waterborne pathogens by microfiltration Chapter | 5

93

exploited to this day. After (Gray, 2014) showed that filtration is not an effective barrier to most pathogens, it has become necessary with another unit process such as coagulation. By developing better methods for detecting bacteria in the first decade of XX, it was found that the system used, despite the high retention (about 97%) of boron pathogens water is not a sufficient method of purifying drinking water. This led to the introduction of the chlorination process into the system as a standard practice (Fig. 5.5). The ability of filters to remove microorganisms depends on the size of the gaps (i.e., the gap between the filter medium). However, the smaller the gaps or pores, the faster the filters are clogged and the water slows through them. The size of the gaps between the settled sand, theoretically, is 10 mm, but in practice, particles already about 4 mm in size are retained. This is related to the phenomenon in which the physical attraction of molecules to the surface of the filter occurs, as a result of which the gaps gradually become smaller. During filtration, microorganisms bound to solid particles with a diameter larger than 0.01 mm are retained without major problems. Table 5.4 presents the effectiveness of removing waterborne pathogens on different types of filters (cross marks indicate the removal rate “xxx” the highest, “-” the smallest). Slow and fast filters are effective in removing cysts and protozoan oocysts only when supported by coagulation and sedimentation. Log-removal rates for Giardia and Cryptosporidium vary between 3.4 and 5.1 and 0.2 and 2.1 (Gray, 2014; Patania et al., 1995; Harrington et al., 2003), respectively, using a combination of coagulationesedimentation and filtration. Proper operation managements are able to removal 2.0-3.0-log and 1.5-2.0-log (Gray, 2014; Standen et al., 1995). The development of 5 m3 at loading rates up to 0.3 m3 m
2 h
1 (Gray, 2014; Twort et al., 2000). To protect against recontamination of drinking water and the elimination of other pathogenic microorganisms, it is advisable to include a disinfection process based mostly on chlorine or ozone.

1.3 Microfiltration 1.3.1 Mass transport in the microfiltration process MF is a physical separation process. It promotes the separation of particles and dissolved constituents from liquids by means of a so-called screening mechanismdsieve mechanism (Scott and Hughes 1996; Gomez-Espinosa and Arizmendi-Cotero, 2019; Zeman and Zydnej, 1996). The membrane separating the feed solution from the permeate or filtrate has a symmetrical or asymmetrical porous structure. The driving force for mass transport through the membrane is the pressure gradient. Because only large particles with diameters above approximately 0.1 mm are separated by the membrane, the diffusion of particles and the difference in osmotic pressure between the feed and filtration solution are negligible, and the mass stream through the

94 Waterborne Pathogens

FIGURE 5.5 Efficiency of water purification in a conventional system and using a microfiltration process (Gray, 2014).

95

Treatment of waterborne pathogens by microfiltration Chapter | 5

TABLE 5.4 Efficiency of the filtration to removal microorganisms. Efficiency of the treatment systemdfiltration Type of organism

Slow sand filtration

Rapid sand filtration

Charcoal filter

Ceramic filter

Bacteria

þþþ

þ

e

þþþ

Protozoa

þþþ

þþ

þþ

þþþ

microfluidic membrane is approximated and described by the following relationship (5.2): X Dp (5.2) Jv ¼ J i V i y Lv Dz i where Jv is the volume flux across the membrane, the subscripts v and i refer to volume and components in the solution, V is the partial molar volume, p is the pressure, Lv is a phenomenological coefficient referring to hydrodynamic permeability of the membrane, Dp is the pressure difference between the feed and filtrate solution, and Dz is the thickness of the membrane. The mass transport in the MF membranes takes place through a viscous flow through the pores. The solid membrane can be considered completely impermeable, which is why hydrodynamic permeability can be expressed by the pore size of the membrane and its porosity along with the viscosity of the solution according to HagenePoiseuille’s law (5.3): Jv ¼

εr 2 Dp 8hs Dz

(5.3)

where Jv is the flux, ε is the membrane porosity, r is the pore radius, h is the viscosity, s is the tortuosity factor, Dp is the pressure difference across the membrane, and Dz is the membrane thickness. Porosity is the ratio of the pore surface to the total membrane area (ε < 1). Tortuosity is the ratio of the actual length of the pore to the thickness of the membrane (taking into account that the pore length is generally slightly longer than the cross-sectional membrane, therefore s > 1). Separation characteristic of membrane is the parameter, which is generally expressed by the retention or rejection and is given by (5.4) ! Cip Ri ¼ 1
f (5.4) Ci where R is the rejection coefficient, C is the concentration, the subscript i

96 Waterborne Pathogens

refers to a given component in the feed and the permeate, and the superscripts f and p refer to the feed and permeate or filtrate solutions. R is always 1 and a function of the particle and the pore size and pore size distribution. R ¼ 0 means complete permeation, and R ¼ 1 means complete rejection (Drioli and Giorno, 2015).

1.4 Waterborne pathogens removal by microfiltration Water contamination can occur at its source, in the place of drawing or its treatment, and also directly in the water supply network. Conventional treatment of drinking water consists of a series of barriers to remove contaminants from water. These steps include coagulation (usually using aluminum sulfate or polymers), sedimentation, filtration, and disinfection. Although coagulation can reduce the concentration of pathogenic microorganisms, filtration and disinfection are considered to be their main barriers. Filtration is the main step to removing waterborne protozoan parasitic and intestinal pathogenic bacteria. Classic water treatment processes do not completely eliminate pathogens and can only deactivate them. Virus removal can be enhanced by coagulation, but filtration cannot be entirely relied on due to the small size of the viruses. Disinfection thus becomes the main barrier to viruses (Bodzek, 2013; AWWA, 2005; Hagen, 1998; Biagini et al., 2000). The effectiveness of water purification processes in removing pathogens is presented in Table 5.5. The Queensland Government (Australia) has provided the following guides to the removal or inactivation of Giardia and Cryptosporidium by various physicochemical water treatment processes: l

l

l l l

l

2.5 log or 99.7% removal for conventional coagulation, clarification, and rapid filtration system 2 log or 99% removal for direct or contact filtration involving coagulation and rapid filtration. 2 log or 99% removal for slow sand filtration. 6 log or 99.9999% removal for MF. 2 log or 99% removal for ozonation at neutral pH, 25 C, and 5e10 CT value. 90% removal for chlorine dioxide oxidation at neutral pH, 25 C, and 78 CT value (Wang et al., 2011; Muhammad et al., 2008).

Low-pressure membrane processes seem to be an attractive alternative as a disinfection process because it involves reducing doses of aggressive chemicals such as chlorine and ozone. In addition, during the classically used chlorine-based processes, unwanted side-by-side disinfection products, i.e., trihalomethanes, may be formed. The interest in using the membrane as part of the disinfection process has intensified also with the emergence of chlorine-resistant pathogens (Cryptosporidium or Giardia) or microorganisms associated with suspensions (Wang et al., 2011; Muhammad et al., 2008).

Type and efficiency of unit processes,% Membrane processes

Type of organism

Coagulation þ sedimentation þ filtration

Ion exchange

Adsorption by PAC pra GAC

Disinfection (including chlorine)

Microfiltration

Ultrafiltration

Nanofiltration/ reverse osmosis

Protozoa

60e100

0e20

20e60

90e100

80e100

90e100

>99.9

Viruses

60e100

0e20

0e20

60e100

20e40

60e90

>99.9

Bacteria

60e100

0e20

0e60

90e100

90e100

90e100

>99.9

Treatment of waterborne pathogens by microfiltration Chapter | 5

TABLE 5.5 The effectiveness of water purification processes in removing waterborne pathogens.

97

98 Waterborne Pathogens

The main problem encountered in membrane filtration processes is contamination of the membrane surfaces used. Membranes of the membrane include inorganic impurities/scaling, organic contaminants, dust/colloidal contaminants, and biofouling (microbial/biological contaminants). Membrane blocking caused by organic and inorganic compounds and microorganisms can occur simultaneously (Nguyen et al., 2012). The occurring phenomena of fouling, biofouling, or scaling are the main factors determining their practical application in purifying or treating water in terms of technology and economy. Factors affecting the adhesion of microorganisms to the surface of the membrane are presented in Fig. 5.6 (Nguyen et al., 2012; Wilbert, 1997; Kang et al., 2004). The use of MF membranes in the treatment of water includes clarification, pretreatment, and removal of particles and microorganisms (Jacangelo et al., 1997; Van der Bruggen et al., 2003). Physical screening is considered to be the main mechanism for removing protozoan oocysts. In the MF process, it is possible to remove pathogens of larger size, i.e., protozoa (3 O 15 mm) or bacteria (0.5 O 10 mm). The pore size of commercially available MF membranes is usually less than 0.3 mm (Bodzek, 2013). Thus, the comparison of the pore size of UF/MF membranes and the size of microorganisms indicates that the UF process guarantees the theoretically proper disinfection of water. The size of viruses varies from 20 to 80 nm, while UF membranes have a pore size of around 10 O 100 nm. Recent studies have shown that various MF and UF membranes ensure removal of C. parvum oocysts and G. muris cysts in the range of >5 log to 7 log (Jacangelo et al., 1997). The use of this unit process allows the removal of 4-log Bacillus spores from water. Hydrophobic MF membranes with a nominal pore size of 0.22 mm allow achieving from 91% to nearly 100% of polio virus rejection (Madaeni et al., 1995). In low-pressure membrane processes such as MF and UF, pathogenic microorganisms are not destroyed or deactivated, but separated and removed, concentrating in the retentate, which can become a problematic waste. Fig. 5.7

FIGURE 5.6 Factors affecting microorganism adhesion to membrane surfaces (Nguyen et al., 2012; Wilbert, 1997; Kang et al., 2004).

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FIGURE 5.7 Size ranges of membrane processes and contaminants (Taylor and Wiesner, 1999).

shows the possibilities of using pressure membrane techniques in removing waterborne pathogens.

2. Summary and conclusions According to recent estimates, there are over 140 species of pathogens that infect humans. These include viruses, bacteria, fungi, and protozoa. The contamination of water with these pathogens can occur at its source, at the place of drawing or its treatment, and also directly in the water supply network. Conventional treatment of drinking water consists of a series of stages to remove impurities from water such as coagulation, sedimentation, filtration, and disinfection. The classic methods used to treat water do not completely eliminate pathogens and lead to their deactivation. The use of MF membranes in the treatment of water includes clarification, pretreatment, and removal of particles and microorganisms. Comparing the pore sizes of membranes used in MF with the size of pathogens, it can be seen that the MF process allows the removal of pathogens with protozoa sizes (3 O 15 mm) and bacteria (0.5 O 10 mm). MF membranes with a pore size of 0.2 mm seem to be a suitable barrier for Cryptosporidium and Giardia and other protozoa of size in the range of 3 O 14 mm. In most cases, the removal of Cryptosporidium and Giardia is greater than 4.5 logs for MF membranes and is sufficient to achieve the set thresholds.

100 Waterborne Pathogens

According to the observations, the number and type of pathogens transmitted in water is constantly growing and their types and varieties are becoming more and more diverse. Therefore, the risk of infection, diseases, and, as a result, death increases. To adapt the highest quality drinking water, a number of processes should be used in combination, which will ensure process reliability and high efficiency of pathogen removal or deactivation. This is due to the variety of durability and growth conditions and resistance of pathogens depending on the conditions of the treatment process. High levels of environmental pollution necessitate systematic research into the transformation of pathogens and determination of toxicity levels. Knowledge of these relations will allow you to choose appropriate remedial measures in terms of the methodology of conducting treatment of contaminated waters.

References Ahmad, A.L., Ismal, S., 2001. Prevention of membrane fouling using electric pulse in dead end microfiltration of titanium suspensions. J. Teknol. 34 (F), 21e38. Adam, R.D., 1991. The biology of Giardia spp. Microbiol. Rev. 55, 706e732. AWWA, 2005. Microfiltration and Ultrafiltration Membranes for Drinking Water (USA). American Water Works Association, Denver. Baker, R.W., 2004. Membrane Technology and Applications, second ed. John Wiley & Sons, Ltd. Bajer, et al., February 10, 2011. Risk factors and control of intestinal parasite infections in sled dogs in Poland. Vet. Parasitol. 175 (3e4), 343. Berger, P.S., Regli, S., Almodovar, L., 1992. Cryptosporidium control in drinking water. In: Proceedings of the 1992 American Water Works Association Annual Conference, Canada, pp. 845e864. Biagini, G.A., Lloyd, D., Kirk, K., Edwards, M.R., 2000. The membrane potential of Giardia intestinalis. FEMS Microbiol. Lett. 192 (1), 153e157. Bitton, G., 2014. Microbiology of Drinking Water Production and Distribution, first ed. John Wiley &Sons, Inc., Hoboken, NJ, USA. Bodzek, M., 2013. Przegląd mo_zliwo
sci wykorzystania technik membranowych w usuwaniu mikroorganizmo´w i zanieczyszcze
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srodowiska wodnego. Inzynieria Ochr. srodowiska 16 (1), 5e37. Bodzek, M., Bohdziewicz, J., Konieczny, K., 1997. Techniki Membranowe w Ochronie

Srodowiska, Wydaw. Politechniki Sląskiej. Bodzek, M., Konieczny, K., 2005. Wykorzystanie proceso´w membranowych w uzdatnianiu wody. Oficyna Wydawnicza Projprzem-Eko 65e485 (Bydgoszcz). Bojar, H., Kłape
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zro´dło zara_zenia ludzi zwierząt pierwotniakami z rodzajo´w Cryptosporidium i Giardia. Med. Ogo´ł. Nauk. Zr. 17 (1), 45e51. Bridle, 2013. Waterborne Pathogens, Detection Methods and Applications, first ed. Academic Press. Brookes, J.D., Antenucci, J., Hipsey, M., Burch, M.D., Ashbolt, N.J., Ferguson, C., 2004. Fate and transport of pathogens in lakes and reservoirs. Environ. Int. 30, 741e759. CDC (Centers for Disease Control and Prevention), 2003a. Giardia and Drinking Water From Private Wells. Available at: http://www.cdc.gov/ncidod/dpd/healthywater/factsheets/pdf/ giardia.pdf.

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Coffey, R., Cummins, E., Cormican, M., Flaherty, V., Kelly, S., 2007. Microbial exposure assessment of waterborne pathogens, human and ecological risk. Assess. Int. J. 13 (6), 1313e1351. Connelly, J.T., Baeumner, A.J., 2012. Biosensors for the detection of waterborne pathogens. Anal. Bioanal. Chem. 402, 117e127. Dembek, Z.F., Anderson, E.L., 2018. Food, waterborne, and agricultural disease. In: Medical Aspects of Biological Warfare byUS Army Medical Department Center and School. Borden Institute. Dore, M.H., 2015. Global Drinking Water Management and Conservation Optimal DecisionMaking, first ed. Springer International Publishing, Switzerland. Drioli, E., Giorno, L., 2015. The Principle of Microfiltration. Springer-Verlag, Berlin Heidelberg. Eisenberg, J.N., Brookhart, M.A., 2002. Disease transmission models for public health decision making: analysis of epidemic and endemic conditions caused by waterborne pathogens. Environ. Health Perspect. 110 (8), 783e790. Fane, A.G., 1996. Membranes for water production and wastewater reuse. Desalination 106, 1e9. Gerba C.P., Haas C.N., Assessment of risks associated with enteric viruses in contaminated drinking water, pp. 489-494. In: Lichtenberg, J.J., Winter, J.A., Weber, CI., Fradkin, 1. (Eds.), Chemical and Biological Characterization of Sludges, Sediments, Dredge Spoils, and Drilling Muds. ASTM STP 976, 1988, American Society for Testing and Materials, Philadelphia. Gomez-Espinosa, Arizmendi-Cotero, 2019. Role of membrane on emerging contaminant removal rosa Marı’a Go’mez-espinosa and Daniel Arizmendi-Cotero. In: The Handbook of Environmental Chemistry. Ecopharmacovigilance Multidisciplinary Approaches to Environmental Safety of Medicines, vol. 66. Springer. Graczyk, T.K., Majewska, A.C., Schwab, K.J., 2008. The role of birds in dissemination of human waterborne enteropathogens. Trends Parasitol. 24, 55e59. Gray, N.F., 2014. Chapter thirty-five e filtration MethodsMicrobiology of waterborne diseases. In: Microbiological Aspects and Risks, second ed., pp. 631e650. Hada
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Janosz- Rajczyk, M., 2003. Cwiczenia Laboratoryjne z Technologii Wody: Praca Zbiorowa. Wydawnictwo Politechniki Czestochowskie. Judd, S., Jefferson, B. (Eds.), 2003. Membrane for Industrial Wastewater Recovery and Re-use. Elsevier Advanced Technology, Oxford. Kang, S.-T., Subramani, A., Hoek, E.M.V., Deshusses, M.A., Matsumoto, M.R., 2004. Direct observation of biofouling in cross-flow microfiltration: mechanisms of deposition and release. J. Membr. Sci. 244, 51e165.

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´ z M., Oczyszczanie wody, 2007, Wydawnictwo Naukowe PWN, Kowal A.L., Swiderska-Bro Warszawa. Kruithof, J.C., Schippers, J.C., Kamp, P.C., Folmer, H.C., Hofman, J.A.M.H., 1998. Integrated multiobjective membrane systems for surface water treatment: pretreatment of reverse osmosis by conventional treatment and ultrafiltration. Desalination 117, 37e48. Leclerc, H., Schwartzbrod, L., Dei-Cas, E., 2002. Microbial agents associated with waterborne diseases. Crit. Rev. Microbiol. 28 (4), 377e409. Levin, R., Kleiman, M.A.R., 2003. Drinking water disinfection in the United States: balancing infectious disease, cancer and costs, market and nonmarket failures. In: Agthe, D.E., Billings, R.B., Buras, N. (Eds.), Managing Urban Water Supply, Water Science and Technology Library, vol. 46. Springer, Dordrecht. MacKenzie, W.R., Hoxie, N.J., Proctor, M.E., Gradus, M.S., Blair, K.A., Peterson, D.E., Kazmierczak, J.J., Addiss, D.G., Fox, K.R., Rose, J.B., Davis, J.P., 1994. A massive outbreak in Milwaukee of Cryptosporidium infection transmitted through the public water supply. N. Engl. J. Med. 331, 161e167. Madaeni, S.S., Fane, A.G., Grohmann, G.S., 1995. Virus removal from water and wastewater using membranes. J. Membr. Sci. 102, 65e75. Majewska, A.C., Graczyk, T.K., Slodkowicz-Kowalsk, A., Tamang, L., Jedrzejewski, S., Zduniak, P., Solarczyk, P., Nowosad, A., Nowosad, P., 2009. The role of free-ranging, captive, and domestic birds of Western Poland in environmental contamination with Cryptosporidium parvum oocysts and Giardia lamblia cysts. Parasitol. Res. 104. Malham, S.K., Rajko-Nenow, P., et al., 2014. The interaction of huma microbial pathogens, particulate material and nutrients in estuarine environments and their impacts on recreational and shellfish waters. Environ. Sci. Process Impacts 16 (9), 2145e2155. Matuszewska, R., 2007. Pierwotniaki paso_zytnicze z rodzaju Cryptosporidium i Giardia. Cze
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obecno
scią oocyst Cryptosporidium w wodzie. Ochrona Srodowiska 29 (3), 25e28. Twort, A.C., Ratnayaka, D.D., Brandt, M.J., 2000. Water Supply, fifth ed. Arnold, London. USEPA, 1989. Drinking water: national primary drinking water regulations; filtration; disinfection; turbidity; Giardia lamblia, viruses, Legionella, and heterotrophic bacteria; final rule. Federal Reg 54 (124), 27486e27541. Van der Bruggen, B., Vandecasteele, C., Gestel, T.V., Doyen, W., Leysen, R., 2003. Review of pressure-driven membrane processes in wastewater treatment and drinking water production. Environ. Prog. 22 (1), 46e56. Wang, L.K., Chen, J.P., Hung, Y.-T., Shammas, N.K., 2011. Membrane and desalination technologies. In: Handbook of Environmental Engineering, vol. 13. Springer, New York Dordrecht Heidelberg London. Wilbert, M.C., 1997. Enhancement of Membrane Fouling Resistance through Surface Modification. A Study Using the Principle of Membrane Fouling and Cleaning to Develop Ways to Enhance Membrane Fouling Resistance; Water Treatment Technology Program Report No. 22. US Department of the Interior, Bureau of Reclamation, Denver, CO, USA. Woolhouse, M.E.J., 2006. Where do emerging pathogens come from? Microbe 1, 511e515. World Health Organization (WHO), 2015. Progress on Sanitation and Drinking-Water: 2010 UpdateReport. World Health Organization (WHO), Geneva, Switzerland. World Health Organization (WHO), 2010. Millennium Development Goals: Progress towards the Health-Related Millennium Development Goals. World Health Organization (WHO), Geneva, Switzerland. World Health Organization (WHO), 2011. Guidelines for drinking-water quality, fourth ed. (WHO), Geneva, Switzerland. Zeman, L.J., Zydnej, A.L., 1996. Microfiltration and Ultraf Iltration Principles and Applications. Mercel Dekker, INC., NewYork.

Chapter 6

Filtration and chemical treatment of waterborne pathogens Jyotirmoy Sarma Department of Chemistry, Kaziranga University, Jorhat, Assam, India

1. Introduction Pathogens normally originate from contamination of water resources. However, contamination may in general take place during treatment, distribution, and various household cases. Treatment of water during its processing and supply is essential in this regard. Without treatment, water is unsuitable for drinking as it absorbs various natural and artificial substances. Treated water must possess certain characteristics such as safe, pleasant taste, clear, colorless, odorless, soft, noncorrosive, and finally low organic matter content (American Water Works Association, 1990). Waterborne illnesses are caused by various bacteria, viruses, and pathogenic microorganisms and usually result from poorly treated drinking water and wastewater or a natural disaster, such as flooding. In general, water to be used for common purposes like drinking, cooking, making any prepared drink, or brushing the teeth should be properly disinfected before use. Improvement in the quality of water in terms of its taste, odor, and color was focused long back by Greeks and Romans (Gray, 1994). This early treatment known as water clarification makes the water transparent by removing visible debris and suspended matter. Water can be made free from larger particles by sedimentation that can be possible in clays pots, through cloth filters and through small sand filtration devices. At the end of 19th century, John Snow, a British physician, mentioned that contaminated water is the source of transmission of cholera among people (Ganczak, 2014). Hence from early 20th century onward, specific focus has been made toward the development of methods for inactivation of disease causing germs. However, in the 21st century also, there is a lack in accessing safe drinking water by a lot in developing countries as per WHO/UNICEF reports. Protective measures such as good source water Waterborne Pathogens. https://doi.org/10.1016/B978-0-12-818783-8.00006-2 Copyright © 2020 Elsevier Ltd. All rights reserved.

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quality, watershed protection, and simple continuously monitored treatments are responsible for achieving better quality treatment.

2. Waterborne pathogens and types of diseases Raw or untreated surface water or groundwater is often contaminated with pathogenic organisms. Chance of contamination also exists during transport and storage (Mintz et al., 1995). Even water treated with a disinfectant often becomes contaminated when collected from a public standpipe and stored in the home. Majority of people across the globe rely on improved water sources, viz. protected wells and springs, public taps, household connections, rainwater harvesting, etc., but are nevertheless contaminated (Bain et al., 2014). It has been reported that an estimated 1.1 billion people worldwide still do not have access to safe potable water in the current 21st century (WHO/UNICEF, 2017). A huge percentage of these people belong to the developing world, majorly in the rural areas and low-income communities (WHO/UNICEF, 2017). Across these communities it is difficult for them to maintain and upgrade smart water supply facilities. Lack of knowledge in water management and violations of drinking water standards are the reasons behind the development of waterborne pathogens across the consumers. It has been cited that immune-compromised people, babies, and the elderly are the most susceptible to pathogen infections and so it is crucial to ascertain that these people have access to good quality water on a daily basis (Momba and Notshe, 2003). Unsafe, i.e., pathogens containing drinking water contributes to fevers such as typhoid, paratyphoid, as well as diseases such as diarrhea, cholera, poliomyelitis, and hepatitis A and E in the world (Mol, 2001). Reported literature says that an estimated 5 million people lose their lives because of water-related disease each year (Gray, 1994). Various types of pathogens in water tend to cause gastrointestinal infections such as diarrhea, dysentery, typhoid shigellosis, and human enteritis (Binnie et al., 2002). Moreover, a huge number of deaths, mainly among young children, are caused from diarrhea annually in developing countries. Diarrheal disease leads to decreased absorption of food and nutrient by the body system, resulting in reduced physical growth and development of health. Generally a wide variety of bacterial, viral, and protozoan pathogens excreted in the feces of humans and animals are known to cause diarrhea. Proper drinking water treatment is essential for fulfilling certain international targets such as poverty reduction, nutrition, childhood survival, school attendance, gender equity, and environmental sustainability (Binnie et al., 2002). In this regard, safe water supply to every household is important. The World Health Organization (WHO) and the United Nations Children’s Fund (UNICEF) have put their valuable effort in providing safe, reliable, and piped-in water to every household (WHO Report, 2007). Household water treatment and safe storage system using methods such as boiling, filtration, or chemical disinfection was found effective in this context.

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The same system can also minimize the risk of recontamination of pathogens (Wright et al., 2003). Hence improved household water management as a component in water, sanitation, and hygiene programs was recognized by various NGOs, research institutions, and private sectors. There are bacterial agents, viral agents, parasitic agents, and chemical agents which cause waterborne illness. There are potable water illnesses and recreational water illnesses. Waterborne illnesses can be caused by ingestion or consuming water, by dermal contact, means the contact of the water with skin, or by inhalation, which is by breathing in a mist. The waterborne pathogens are also transmitted via ingestion of contaminated food and other beverages, by person-to-person contact, and by direct or indirect contact with infected feces (Gray, 2008). Among the bacterial pathogens, Escherichia coli, Salmonella, Shigella, Campylobacter, Salmonella typhi, Vibrio cholerae, and Pseudomonas are mostly encountered in the environment. The bacterium E. coli causes diarrheal illness, and it is identified as an enterohemorrhagic E. coli because in its most severe form, it can cause the disease hemorrhagic colitis (Gray, 2008). The sources for bacteria are cattle, deer, goats, and sheep. Humans can also be a reservoir of the same. It is typically associated with contaminated food and water (Binnie et al., 2002). Salmonella species is another bacteria causing diarrheal illness known as salmonellosis. Humans and animals are the reservoir, and it’s typically associated with contaminated food and water. Shigella species causes diarrheal illness known as shigellosis. Humans and primates are the reservoir for this pathogen. Shigella species, in its two counterparts namely Shigella sonnei and Shigella flexneri, causes shigellosis in the United States. Moreover, in developing countries, Shigella dysenteriae is the primary cause of illness associated with this pathogen (Reasoner, 1992). S. typhi is one more type of bacteria. It causes diarrheal illness, also known as typhoid fever. Humans are the reservoir for this pathogen. Campylobacter causes diarrheal illness and its source is primarily poultry, animals, and humans. Nevertheless, a common important bacterium is V. cholerae. It causes diarrheal illness, also known as “cholera.” It is reported that the watery diarrhea “V. cholerae” is the most common cause of illness and deaths in the developing world (Reasoner, 1992). It is typically associated with aquatic environments, shellstocks, and human. V. cholerae has also been associated with ship ballast water that also causes disease outbreak. Finally, another two more types of known bacterial pathogens are Pseudomonas and Legionella. Legionella, which is basically a bacterium, causes a respiratory illness known as legionellosis. There are two illnesses associated with legionellosis: the first is Legionnaire’s disease, which causes a severe pneumonia, and the second is Pontiac fever, which is a nonpneumonia illness; it’s typically an influenza-like illness and it’s less severe (Rotz et al., 2002). Legionella is naturally found in water, both natural and artificial water sources. Various types of waterborne microorganisms such as bacteria, molds, fungi, viruses, and protozoans cause health risk to mankind. These organisms are found to be resistant to antibiotics. Pseudomonas,

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a pathogen, also causes serious infections to human health (Vanholder et al., 1990). Pseudomonas bacteria are caused by dermal contact with water. It can cause dermatitis, which is an inflammation of the skin, or it can cause otitis, which is an infection of the ear. Pseudomonas is typically associated with soil and water. On the other hand, there are several water-transmitted viruses, notably rotavirus, para-rotavirus, reovirus, hepatitis A and E, and norovirus (Pond, 2003). The common hepatitis A virus causes inflammation of the liver, and the reservoir for hepatitis A virus is humans. Another one norovirus causes diarrheal illness. Humans are also the reservoir for this virus. Protozoans such as Cryptosporidium, Giardia, and Schistosomatidae are well-known for community-acquired waterborne infections (Naumova et al., 2003). Several bacterial infections are caused by protozoans. These are also called parasitic pathogens. Cryptosporidium basically a parasite causes diarrheal illness known as cryptosporidiosis. It is typically associated with animals and humans, and it can be acquired through consuming fecally contaminated food, contact with fecally contaminated soil and water. Another parasite is Giardia, which causes diarrheal illness known as giardiasis. It is primarily associated with water. It is the most common pathogen in waterborne outbreaks. It can also be found in soil and food. Commonly, humans and animals are the reservoirs for this pathogen. One more important parasite is Schistosomatidae. It is acquired through dermal contact, cercarial dermatitis. It is commonly known as swimmer’s itch. The reservoirs for this pathogen are aquatic snails and birds. One important category of waterborne outbreak is caused by chemical illness. Chemical illnesses associated with potable water and recreational water are too plenty to discuss. They are typically associated with cross-connections and runoff. However, some chemical contamination can occur naturally. Basically immune status of human along with microbe virulence and dose of exposure all contribute to the risk of disease development. Therefore, a variety of waterborne microorganisms causes several diseases that make human life at higher risk. Drinking water in addition to microbial contaminants contains also various chemical contaminants. These include both organic and inorganic compounds. Examples of organic chemicals that may be toxic at certain concentrations are the polychlorinated and polybrominated biphenyls as well as benzenes (Gray, 2008). Symptoms arising from the toxic effects of these chemicals include diarrhea, nausea, convulsions, blurred vision, and difficulty in breathing. Organic pollutants may also cause arteriosclerosis, heart diseases, hypertension, emphysema, bronchitis, and kidney and liver dysfunction too. On the other hand, inorganic chemicals are also creating health problems in the human system. In this context, nitrates basically are inorganic salts accumulating in the blood stream and resulting in methemoglobinemia, the symptom for which is a bluish skin. Nevertheless, high concentrations of phosphate can cause health problems such as kidney damage and osteoporosis. Natural organic matter (NOM) analogues such as small hydroxy and dihydroxybenzoic

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(DHBA) acids are also sometimes recognized as components of pollutants in aquatic ecosystems (Borah et al., 2011a). Waste dyes and polymeric compounds from textile and paint industries in urban areas act as major source of water pollution. Moreover, several inorganic elements ranging from anions, soft and heavy metals such as chloride, magnesium, iron, aluminum, copper, arsenic, and lead are found to be present in drinking water. These inorganic contaminants pose public health risks at high concentrations (Gray, 2008).

3. Source and transmission of waterborne pathogens Source of water is primarily responsible for the pathogens. Urban and rural communities in several countries across the world are the targets of waterborne diseases. Communities in general rely on river, stream, and pond water sources. People therein are therefore prone to the devastating effects of waterborne diseases and their complications. Morbidity and mortality of people in communities depend on these waterborne diseases. Human fecal waste contaminated with water is a source of disease (Gleeson and Gray, 1997). A drop of fecal matter may contain millions of microorganisms, which are the agents of diseases. The human feces together with human urine are collectively referred to as human waste. Sewage and wastewater is also a major source of pathogens and diseases. In rural areas, occurrence of pollution by untreated sewage is very high because of lack of proper treatment facilities. Animal and agricultural wastes are also greatly responsible for several potentially pathogenic microbes (Gleeson and Gray, 1997). In agricultural purposes, the nutrient content of the used manure and fertilizers encourage the growth of plants and algae in water. The waterborne microbes decompose them during death and consume oxygen dissolved in water during decomposition. This leads to a drop in oxygen level in water to the extent that oxygendependent animals may die. This is known as “eutrophication.” Nevertheless, the development of pathogens in waterbody because of temperature change results in thermal pollution. This is believed to occur by water circulation between sources such as lakes, rivers, etc., and sinks such as factories and power plants (Gray, 1994). Water in the hospitals is also a major concern for the patients therein. Various types of waterborne microbes in hospital water also affect the patients in and around the developing countries. Point-of-use water filtration provides way for control of such infections. Infections such as pneumonia and urinary tract infections are common in this regard. An important microorganism found in hospital water is Legionella species, which is introduced earlier. Transmission of this occurs by inhalation of microbes that are commonly generated during showering or running bath water (Herwaldt et al., 1992). Utensils washed with the Legionella species contaminated water can spread infections in patients. Pathogens and the related diseases are transmitted from one person to another by various environmental pathways. For example, excreted pathogens

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in the feces of an infected person will, in a conventional system, end up in sewage. Generally the wastewater undergoes treatment in municipal wastewater treatment plants. This process reduces the levels of microorganism content. However, in the sewage, high concentrations of pathogens may still remain. Again during discharge of the treated wastewater into receiving waters, transmission of the pathogens to humans occurs (Rotz et al., 2002). Role of municipal water treatment in preventing disease transmission to the consumers is vital for drinking water purposes. Sewage sludge during its use in agriculture as a fertilizer serves as a source of pathogens. Transmission of pathogens present therein via crops is possible if the treatment or storage time has not been sufficient. Moreover, some pathogens can be transmitted between animals and humans, termed as zoonoses, whose reservoirs are basically both domestic and wild animals. Transmission of pathogens to water media can occur via the runoff from pastures and agricultural land fertilized with animal slurry, manure, or sludge because of heavy rains or snowmelt. Some other common sources of microbial pollution to watercourses also exist, for example, leaking septic tanks, waterfowl, etc. In cases where crops are irrigated with wastewater, transmission of pathogens to humans (and animals) can occur directly or via crops, aerosols, and primarily via groundwater. Hence environmental transmission of pathogens can clearly result in infections and diseases primarily and also secondary person-to-person transmission can occur. In this way, the circulation of pathogens in the environment will continue. It is known that these pathogens cause several disease outbreaks in both developed and developing countries across the world. Surface water systems are mainly responsible for the largest waterborne outbreaks. Nevertheless, most outbreaks occur in groundwater systems on account of contamination of the water source through (surface) wastewater infiltration (Singh and McFeters, 1992). In this context of disease outbreak, recreational water along with reuse of wastewater and sludge also imposes a serious role. However, the reasons for the occurrence of disease outbreaks by pathogens are helpful for the development of proper treatment technologies. Most of the reasons reflect the lacking in either mechanical or physicochemical treatment processes. Keeping in mind about the types, source, and transmission of pathogens, appropriate treatments need to be taken as preventive measures for the development of water and wastewater systems. As per the theme of this chapter, filtration and chemical treatments for removal of waterborne pathogens will be focused in the next sections.

4. Filtration and chemical treatment 4.1 Filtration methods for treatment of pathogens The three primary group’s pathogenic microorganisms that can be transmitted from drinking water to humans with proper size are protozoans (5e100 m),

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bacteria (0.5e1 m), and viruses (0.01e0.1 m). Processes for removal of pathogens include pretreatment; coagulation, flocculation, and sedimentation; and filtration. Pretreatment is before treatment in the plant for improving the water quality. A lot of treatment options are there for eliminating pathogens from drinking water (Kool, 1979). However, finding the right solution is important. The water treatment systems can be classified into three categories, basically (1) household and small-scale water treatment, (2) drinking water treatment in plants/industries, and (3) wastewater treatment in plant/industries.

4.1.1 Household and small-scale water treatment Household water treatment systems should be cheap, robust, compact, hygienic, and odorless, require little maintenance, and can be operated by unskilled persons. The commonly applied systems are cesspools, septic tanks, rotating biological contactors (RBCs), constructed wetlands, and small complete treatment systems including sand filters (Hill and Lorch, 1987). Almost all of these involve filtration mechanism in their processing somehow. Both cesspool and septic tank are storage tanks where the settleable solids are separated from the liquid fraction by filtration processes. These systems are used in combination with some secondary treatment systems like percolating filters for water treatment in various communities. Filtration here acts as a secondary treatment system. Among small complete treatment systems, (1) biological or submerged aerated filters (BAFs), (2) RBCs, (3) sand filters, and (4) peat filters are widely available (Wang and Hung, 2007). Biocycle is an important example of a BAF system. It is a complete singletank treatment system composed of both a septic tank and a submerged aerated filter for secondary treatment. RBCs and percolating filters includes the example of Bioclere that incorporates a filter system which is not a submerged system but a minipercolating filter with a small random plastic filter medium (Hill and Lorch, 1987). Simple filters like sand filters consist of graded layers of sand and pea gravel are applied for the secondary treatment of septic tank wastewaters. Their action is very similar to that of percolating filters. Fibrous peat has characteristic properties such as high adsorptive capacities and these filters are efficient for suspended solids removal as well. In addition, it has been observed in villages of Bangladesh using cloth, generally a flat, unfolded piece of an old sari, for filtration purpose of home prepared drinks was found very effective (Water Environment Federation, 2006). Generally at home, the installation of a small UV water sterilizer unit installed directly to the kitchen tap ensures microbially safe water. However, destruction of the protozoan cysts needs physical removal. This is possible by using a 1 mm pore-sized fiber cartridge filter, which is placed along with the UV sterilizer (Wang and Hung, 2007). The filter will also remove any particulate matter and thereby increases the efficiency of the sterilization.

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4.1.2 Drinking water treatment in plants/industries During drinking water treatment, filtration is the most widely used process. Water filtration is done through a porous bed of inert medium, usually silica or quartz sand. Filter process may be either slow or rapid and operated by gravity or the water can be forced through the medium under pressure. Two types of filters are encountered in this context. One is rapid gravity filters and the other slow sand filters. Rapid gravity filters are basically operated by gravity. They contain coarse grades of sand and the gaps between the interstices are comparatively large, allowing the water to rapidly pass through leaving behind the suspended solids (Casey, 1997). Filters are made up of a layer of coarse sand 0.5e1.0 mm in diameter. In case of slow sand filters, a much finer sand of 0.15e0.3 mm in diameter is utilized. Slow sand filters are constructed with a layer of the fine sand over a graded layer of coarse sand. Here, a gelatinous layer rich in microorganisms forms, which acts in the treatment of the water. Waterborne pathogens are responsible for coliforms which are normal inhabitants of water. The presence of coliform in a water sample or “coliform testing” can be achieved by membrane filtration technique. Here, a fixed volume of water is passed through a sterile membrane filter having a pore size of w0.45 mm. This retains all the pathogens present. The membrane filter is placed onto culture medium, which allows pathogen growth to form colonies (Wang and Hung, 2007). This is done by incubation of the membrane filter on the culture medium for a prescribed period and temperature. During this incubation period, the nutrients diffuse from the culture medium through the membrane and the coliform bacteria are able to multiply and form recognizable colonies that can then be counted. For different pathogenic types, different culture media and incubation conditions are essential. Storage is an important water treatment process for pathogen removal. Bacteria and viruses are significantly reduced during water storage in reservoirs. Increased temperature and several biological factors especially in spring and summer seasons ensure 90%e99.8% reductions of E. coli, whereas the percentage reduction is observed to be less (75%e90%) during the autumn and winter season. The longer the storage time, the greater the overall reduction achieved. However, pathogens with small size and densities are not easily removed by storage (Stevenson, 1998). Moreover, temperature is also an important contributing factor. For example, poliovirus was decreased by 99.8% in 15 days at 15e16
C compared with 9 weeks for a similar decrease at 5e6
C. Sand filtration and activated carbon filtration have found wide application in water treatment. In case of rapid sand filtration, removal of viruses and bacteria from water needs prior coagulation for effectiveness. But slow sand filtration is effective removing up to >90% pathogens (Casey, 1997).

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Activated carbon can remove viruses by adsorption process onto the carbon. This takes place by ionic interaction between positively charged amino groups on the virus and negatively charged carboxyl groups on the surface of the adsorbent (Sincero and Sincero, 2003). The removal mechanism is surface charge dependent. Cysts have been removed by rapid sand filtration process with polyelectrolyte coagulant addition. However, slow sand filtration with 99.98% and 99.99% removal efficiencies was found effective method in case of both Cryptosporidium and Giardia cysts.

4.1.3 Wastewater treatment in plant/industries The chemical nature of the wastewater will determine whether the environmental conditions are suitable for the survival or even the growth of pathogens; however, factors such as hardness, pH, ammonia concentration, temperature, and the presence of toxic substances can all increase the mortality rate of the microorganisms. It is convenient to look at the wastewater treatment plant as an enclosed system with inputs and outputs. It is a continuous system so the outputs, in the form of sludge and a final effluent, will also be continuous. While a comparison of the number of pathogens in the influent with the final effluent will provide an estimate of overall removal efficiency, it will not give any clues as to the mechanism of removal. Essentially pathogens are killed within the treatment unit, discharged in the final effluent, or concentrated in the sludge which will result in secondary contamination problems if disposed either to agricultural land or into coastal waters (Gray, 2008). Activated sludge process and fixed film reactors are two important unit processes for removal of pathogens from wastewater. Both the processes show above 90% removal. The prime removal method of pathogens in the activated sludge process is adsorption onto sludge flocs, which is a part of filtration method followed by assimilation and mineralization processes. However, in fixed film reactor process, percolating filters play a significant role in the removal mechanism. These filters remove the pathogens by holding them via adsorption onto the film surface (Stevenson, 1998). However, the major limitation of percolating filtration in the removal of pathogens lies in their physical adsorption from suspension. Percolating filtration is not very effective in the removal of parasite ova and cysts as per literature. All these are biological treatment processes. The microbial biomass produced in these units can be separated using sedimentation process. The microbial biomass acts as a film, which is growing continuously. Purification is obtained by contact of the wastewater with this film. The heterotrophic microorganisms present in the film degrade the organic matter present in the wastewater. In fixed film reactors, the medium is stationary but moving medium, i.e., the medium itself

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moves through the wastewater and is also available in some reactors such as RBCs and fluidized beds. These are basically aerobic filter systems. However, anaerobic filters are used for the treatment of moderately strong organic wastewaters and denitrification. Nitrification and denitrification processes in the treatment plant are basically carried out by their respective filters. These are submerged filters containing an inert medium where films of nitrifying and denitrifying bacteria develop (Gray, 2004). Wastewaters can be categorized into domestic (sanitary) wastewater commonly known as sewage, industrial (trade) wastewaters, and, finally, municipal wastewater, which is a mixture of the two. Raw sewage contains small and visible particles of organic materials that readily settle out of suspension. Raw sewage is basically a turbid liquid. However, municipal wastewaters are generally contaminated by dyes and other colored discharges (Wang and Hung, 2007). Animal waste is major concern for pathogen transfer to humans because of poor disposal and handling issue. These wastes largely contain antibiotic-resistant bacterial pathogens because of the use of antibiotics in animal feeds. Careful work practice is needed during working with sewage as this spreads disease by the living and dead bacteria’s present therein. Commonly, the workers are vaccinated for the possible diseases. A wastewater treatment plant consists of a variety of major units such as screening, filtration, centrifugation, reverse osmosis (RO), ultrafiltration (UF), microfiltration (MF), and nanofiltration (NF) (Stevenson, 1998). Large materials are removed by screening process, which are unhygienic because of fecal matter contamination. Nonchemical disinfection of pathogens can be done by using membrane filtration. Filtration is usually applied during the pretreatment of industrial wastewaters. Pretreatment is necessary to prevent damage to the treatment processes (Harza, 2005). Artificial wetlands or reed beds which originate from the application of plants in wastewater treatment also involve in the removal of pathogens by filtration process. However, wastewaters require a primary settlement before reed bed operation. Natural treatment systems such as infiltrationepercolation also hold the filtration facility in its multiple basins. The four major filtration units such as RO, NF, UF, and MF fall under the membrane filtration technology (Water Environment Federation, 2006). This technique applies synthetic polymeric membranes for removal of minute particles and pathogens from contaminated water under pressure. Conventional treatment processes are not found effective for removal of small particles and microorganisms. However, membrane filtration technique because of small pore size and volume of the membranes was found effective in this context. This technique has found wide application in advanced and tertiary

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treatment of potable and wastewaters. The basic features of these four filtration methods can be tabulated as below: Filtration type

Operating pressure (kPa)

Pore size (mm)

Application on removal of Insoluble particles and turbidity Soluble nonionic solutes

Microfiltration

30e50

0.1

Ultrafiltration

30e50

0.01

Nanofiltration

500e1000

0.001

1000e5000

0.0001

Reverse osmosis

Ca2þ, Mg2þ, dissolved organic molecules Salts

Microbes removed Algae, protozoa, and most of the bacteria Algae, protozoa, and most of the bacteria and viruses Algae, protozoa, and most of the bacteria and viruses Algae, protozoa, and most of the bacteria and viruses

Reproduced from Stevenson, D.G., 1998. Water Treatment Unit Processes. Imperial College Press, London.

In MF technique, a variety of membranes exists such as tubular, capillary, hollow fiber, and spirally wound sheets. Here, the membranes are constructed from a thin polymer film with a uniform pore size and a high pore density. Membranes require proper servicing with either water or gas under pressure for clearance of the micropores. This technique can remove microbial cells, large colloids, and small particles in the size range (