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Book Details
Abstract
Domestic animals contaminate recreational waters and drinking-water sources with excreta and pathogens; but this threat to public health is inadequately understood and is insufficiently addressed in regulations. More than 85% of the world’s faecal wastes is from domestic animals such as poultry, cattle, sheep and pigs. These animals harbor zoonotic pathogens that are transported in the environment by water, especially runoff. However little information exists on health effects associated with exposure to this potential hazard to human health; and water standards focused on control of human fecal contamination do reflect the contribution of non-human fecal contamination to risk. Does compliance with current monitoring practices using microbial indicators provide protection against animal and bird sources of fecal contamination?
Prepared with contributions from a group of international experts, Animal Waste, Water Quality and Human Health considers microbial contamination from domestic animal and bird sources and explores the health hazards associated with this microbial contamination and approaches to protecting public health. Animal Waste, Water Quality and Human Health will be of interest to regulators with responsibility for recreational waters, drinking water quality and water reuse; policymakers working in water quality, public health and agriculture; decision makers responsible for livestock management; and scientists and practitioners concerned with many affected subjects.
Topics covered include:
- Credible waterborne zoonotic pathogens are discussed and ranked according to their potential hazard level. Each pathogen is described with regard to their sources, reservoirs, and infectivity.
- Faecal production rates of various domestic animals are discussed, alongside pathogen transmission in animal populations, pathogen prevalence in animals and “supershedders”.
- Transport of fecal indicator organisms and their episodic occurrence in catchments.
- Interventions for improving food safety and reducing production losses.
- The impact of interventions, e.g. enhanced attenuation and storage to prevent spills; benchmarking against best management practices to reduce diffuse source contamination.
- Models to inform design of farm-scale best management practices and the effectiveness of best management practices for attenuating pathogen transport within catchments.
- The complex nature of human exposure to zoonotic waterborne pathogens; including the relationships among livestock waste contamination, water impairment, zoonotic pathogens, and human infection and illness.
- Human exposure interventions include case studies that discuss eradicating disease in discharging populations, adding filtration to minimal treated water to reduce Cryptosporidium occurrence and UV disinfection of beach waters to reduce beach postings.
- Indicators, sanitary surveys and source attribution techniques; risk assessment of exposure to zoonotic pathogens, including an interactive risk comparison approach.
- A review of epidemiological studies that address the relationship between swimmer illness and exposure to waters contaminated by nonhuman fecal wastes.
- Economic evaluation of the costs and benefits associated with animal waste management and human health.
Table of Contents
| Section Title | Page | Action | Price |
|---|---|---|---|
| Cover\r | Cover | ||
| Contents | v | ||
| Summary Statement1 | vii | ||
| 1:\rIntroduction | 1 | ||
| 1.1 PROBLEM DESCRIPTION | 3 | ||
| 1.2 CHALLENGES | 5 | ||
| 1.3 OPPORTUNITIES | 7 | ||
| 1.4 DRIVING FORCES AND FUTURE PERSPECTIVES | 9 | ||
| 1.5 SCOPE OF THIS BOOK | 11 | ||
| 1.6 STRUCTURE OF THIS BOOK | 12 | ||
| REFERENCES | 14 | ||
| 2:\rAssessing the importance of zoonotic waterborne pathogens | 17 | ||
| 2.1 INTRODUCTION | 17 | ||
| 2.2 RANKING ZOONOTIC PATHOGENS ASSOCIATED WITH WATERBORNE DISEASES | 19 | ||
| 2.3 WATERBORNE PATHOGENS\r | 21 | ||
| 2.3.1 Protozoa | 21 | ||
| 2.3.2 Bacterial pathogens | 37 | ||
| 2.3.3 Viruses | 52 | ||
| 2.4 CONCLUSIONS | 52 | ||
| REFERENCES | 53 | ||
| 3:\rZoonotic waterborne pathogen loads in livestock | 73 | ||
| 3.1 INTRODUCTION\r | 73 | ||
| 3.1.1 Objectives | 73 | ||
| 3.1.2 Livestock status and trends in developed and developing countries | 74 | ||
| 3.1.3 Pathogen loading by livestock and recreational waterborne zoonotic disease | 75 | ||
| 3.1.4 Environmental loading rate of zoonotic pathogens in livestock | 76 | ||
| 3.2 WATERBORNE ZOONOTIC PROTOZOA | 79 | ||
| 3.2.1 Cryptosporidium parvum\r | 79 | ||
| 3.2.2 Giardia duodenalis | 83 | ||
| 3.3 WATERBORNE ZOONOTIC BACTERIA\r | 85 | ||
| 3.3.1 E. coli O157:H7 | 85 | ||
| 3.3.1.1 Risk factors for outbreaks of E. coli O157:H7 | 86 | ||
| 3.3.1.2 Faecal shedding of E. coli O157:H7 by livestock | 87 | ||
| 3.3.2 Campylobacter | 89 | ||
| 3.3.2.1 Faecal shedding of Campylobacter by livestock\rand wildlife | 90 | ||
| 3.3.2.2 Source attribution of Campylobacter infections | 91 | ||
| 3.3.3 Salmonella enterica | 92 | ||
| 3.3.3.1 Salmonella serotypes associated with human infection | 93 | ||
| 3.3.3.2 Shedding of Salmonella by livestock | 94 | ||
| 3.3.4 Survival of zoonotic bacterial pathogens in the farm environment | 94 | ||
| 3.4 METHODOLOGICAL CONCERNS REGARDING MONITORING PATHOGEN LOADS | 95 | ||
| 3.5 CONCLUSIONS | 98 | ||
| ACKNOWLEDGEMENTS | 99 | ||
| REFERENCES | 99 | ||
| 4:\rZoonotic waterborne pathogens in livestock and their excreta – interventions | 115 | ||
| 4.1 INTRODUCTION | 115 | ||
| 4.2 RISK-BASED APPROACHES AND THE RATIONALE FOR ANIMAL-BASED INTERVENTIONS | 116 | ||
| 4.3 CONTROL POINT 1: MINIMIZING EXPOSURE OF LIVESTOCK TO PATHOGENS | 120 | ||
| 4.3.1 Specific pathogen-free animals | 120 | ||
| 4.3.2 Biosecurity-raising livestock in a disease-free bubble | 121 | ||
| 4.3.3 Reducing exposure from high risk animals | 123 | ||
| 4.3.4 Reducing exposure from wildlife | 123 | ||
| 4.3.5 Reducing exposure from litter and bedding | 124 | ||
| 4.3.6 Reducing exposure from feed | 125 | ||
| 4.3.7 Reducing exposure from water | 125 | ||
| 4.4 CONTROL POINT 2: INCREASING HOST IMMUNITY/RESISTANCE | 126 | ||
| 4.4.1 Disease resistant livestock | 126 | ||
| 4.4.2 Vaccination | 126 | ||
| 4.4.3 Management practices to increase resistance to disease | 132 | ||
| 4.5 CONTROL POINT 3: MANIPULATION OF THE MICROBIAL ECOLOGY OF THE HOST’S GASTROINTESTINAL TRACT | 132 | ||
| 4.5.1 Prebiotics, probiotics and competitive exclusion | 133 | ||
| 4.5.2 Bacteriophages | 134 | ||
| 4.5.3 Antimicrobials | 135 | ||
| 4.6 CONTROL POINT 4: TREATMENT OF ANIMAL WASTES TO REDUCE ZOONOTIC PATHOGENS | 137 | ||
| 4.7 CROSS-CUTTING ISSUES | 139 | ||
| 4.7.1 Developing country issues in controlling animal pathogens at the farm level | 139 | ||
| 4.7.2 Epidemiological studies to identify putative risk factors | 141 | ||
| 4.7.3 Emerging trends in the control of zoonotic pathogens at the farm level | 141 | ||
| 4.8 CONCLUSIONS | 142 | ||
| REFERENCES | 143 | ||
| 5:\rTransport of microbial pollution in catchment systems | 157 | ||
| 5.1 POTENTIAL OF MICROBIAL MODELS TO DESCRIBE CATCHMENT COMPLEXITY | 157 | ||
| 5.2 EMPIRICAL DATA ON ANIMAL MICROBIAL SOURCES | 159 | ||
| 5.3 EMPIRICAL DATA ON HUMAN MICROBIAL SOURCES | 168 | ||
| 5.4 MICROBIAL TRANSPORT | 170 | ||
| 5.5 CONCLUSIONS | 180 | ||
| REFERENCES | 186 | ||
| 6:\rEffectiveness of best management practices for attenuating the transport of livestock-derived pathogens within catchments | 195 | ||
| 6.1 INTRODUCTION | 195 | ||
| 6.2 CATCHMENT DYNAMICS OF LIVESTOCK-DERIVED PATHOGENS\r | 198 | ||
| 6.2.1 Hydrological pathways | 198 | ||
| 6.2.2 Processes of microbial attenuation | 199 | ||
| 6.3 LIMITATIONS OF THE EXISTING EVIDENCE BASE | 199 | ||
| 6.4 OUTLINE OF PRESENT DATABASE | 201 | ||
| 6.5 BMPs TO ATTENUATE PATHOGEN TRANSFERS TO WATERCOURSES\r | 236 | ||
| 7:\rExposure | 257 | ||
| 7.1 INTRODUCTION | 257 | ||
| 7.2 RELEVANT WATER TYPES | 258 | ||
| 7.3 FACTORS INFLUENCING HUMAN EXPOSURE, INFECTION AND ILLNESS | 258 | ||
| 7.3.1 Environment | 260 | ||
| 7.3.2 Pathogen | 264 | ||
| 7.3.3 Host | 270 | ||
| 7.3.3.1 Inhalation | 270 | ||
| 7.3.3.2 Direct body contact | 270 | ||
| 7.3.3.3 Oral ingestion | 271 | ||
| 7.4 ADEQUACY OF TOOLS FOR ASSESSMENT AND MONITORING; REGULATORY CHALLENGES | 274 | ||
| 7.5 SUMMARY | 275 | ||
| REFERENCES | 276 | ||
| 8:\rExposure interventions | 283 | ||
| 8.1 A CONCEPTUAL FRAMEWORK FOR EXPOSURE INTERVENTIONS | 283 | ||
| 8.2 A STEP-WISE APPROACH TO MEDIATING WATERBORNE ZOONOSES\r | 286 | ||
| 8.2.1 Weight of evidence | 286 | ||
| 8.2.2 Faecal indicator organisms as a gauge of water quality | 287 | ||
| 8.2.3 Alternative or secondary indicators of faecal contamination | 288 | ||
| 8.2.4 Source attribution (microbial source tracking, MST) | 288 | ||
| 8.2.5 Sanitary surveys | 289 | ||
| 8.2.6 Mathematical modeling | 290 | ||
| 8.2.7 Limitations of current methodologies | 290 | ||
| 8.3 OPPORTUNITIES FOR EXPOSURE REDUCTION | 290 | ||
| 8.3.1 Eradication and control measures | 291 | ||
| 8.3.2 Physical alterations | 291 | ||
| 8.3.3 Regulatory measures | 292 | ||
| 8.3.4 Public health education | 293 | ||
| 8.3.5 Confounding factors: political, cultural, monetary, access, and climate change | 294 | ||
| 8.4 EXAMPLES OF EXPOSURE INTERVENTIONS | 296 | ||
| 8.4.1 Schistosoma japonicum (schistosomiasis) | 296 | ||
| 8.4.2 Leptospirosis | 297 | ||
| 8.4.3 Salmonella | 298 | ||
| 8.4.4 Campylobacter | 299 | ||
| 8.4.5 E. coli O157:H7 | 300 | ||
| 8.4.6 Cryptosporidium | 301 | ||
| 8.4.7 Mitigation in the absence of a definitive host attribution | 302 | ||
| 8.5 CASE STUDIES | 302 | ||
| 8.6 FUTURE DIRECTIONS IN RISK ASSESSMENT CAPABILITIES | 308 | ||
| ACKNOWLEDGEMENTS | 309 | ||
| REFERENCES | 309 | ||
| 9:\rIndicators, sanitary surveys and source attribution techniques | 319 | ||
| 9.1 FAECAL INDICATOR ORGANISMS (FIOs) - AN HISTORICAL PERSPECTIVE\r | 319 | ||
| 9.2 FIOs - ALTERNATIVE/SECONDARY INDICATORS AND NEW APPROACHES\r | 321 | ||
| 9.2.1 Alternative or secondary indicators | 321 | ||
| 9.2.2 New approaches -\rpredictive modeling | 323 | ||
| 9.3 SANITARY SURVEYS | 324 | ||
| 9.4 SOURCE ATTRIBUTION TECHNIQUES | 328 | ||
| 9.4.1 Chemical analysis (source tracking/water quality indicators) | 329 | ||
| 9.4.2 Limitations and challenges of faecal source tracking methods | 331 | ||
| 9.4.3 Correlation of host-specific markers with FIOs and pathogens | 333 | ||
| 9.4.4 Quantification of source specific markers | 335 | ||
| 9.5 PRACTICAL UTILITY OF SOURCE ATTRIBUTION STUDIES | 336 | ||
| 9.6 STUDY DESIGN - INCORPORATING A HOLISTIC APPROACH\r | 337 | ||
| 9.7 CASE STUDIES | 338 | ||
| ACKNOWLEDGEMENTS | 344 | ||
| REFERENCES | 344 | ||
| 10:\rComparative risk analysis | 361 | ||
| 10.1 ESSENTIALS OF RISK ASSESSMENT | 361 | ||
| 10.1.1 Key elements | 363 | ||
| 10.1.2 Principles of risk assessment | 364 | ||
| 10.1.3 Pathogen selection | 364 | ||
| 10.2 THREE RISK ASSESSMENT PARADIGMS | 366 | ||
| 10.2.1 The diseases | 370 | ||
| 10.2.2 Assessing infectivity | 370 | ||
| 10.2.3 Assessing severity | 371 | ||
| 10.2.4 The sources | 372 | ||
| 10.3 THE EXPOSURES AND RISK FACTORS | 372 | ||
| 10.3.1 Ingestion rates | 373 | ||
| 10.3.2 Climate change | 373 | ||
| 10.4 THE COMPARATIVE RISK MODEL\r | 374 | ||
| 10.4.1 Background and objectives | 374 | ||
| 10.4.2 Model structure and interface | 375 | ||
| 10.4.3 Model logic | 376 | ||
| 10.4.4 The questions | 378 | ||
| 10.4.4.1 Identifying the source | 379 | ||
| 10.4.4.2 Estimating load | 381 | ||
| 10.4.4.3 Estimating contamination of the recreational water | 382 | ||
| 10.4.4.4 Exposure | 385 | ||
| 10.4.4.4 Relative risk calculations | 388 | ||
| 10.5 CONCLUSIONS | 390 | ||
| ACKNOWLEDGEMENTS | 391 | ||
| APPENDIX: BASIS OF VALUES PRESENTED IN TABLE 10.1 | 392 | ||
| ID50 VALUES | 392 | ||
| CAMPYLOBACTERIOSIS | 392 | ||
| E. COLI\rO157:H7 INFECTION | 392 | ||
| SALMONELLOSIS | 392 | ||
| GIARDIASIS | 393 | ||
| CRYPTOSPORIDIOSIS | 393 | ||
| PATHOGENS IN ANIMAL EXCRETA | 393 | ||
| PATHOGEN SURVIVAL (T90) AND EFFECT OF SUNLIGHT | 402 | ||
| Campylobacter, E. coli and Salmonella | 402 | ||
| Giardia and Cryptosporidium | 402 | ||
| REFERENCES | 403 | ||
| 11: Epidemiological studies on swimmer health effects associated with potential exposure to zoonotic pathogens in bathing beach water – a review | 415 | ||
| 11.1 INTRODUCTION | 415 | ||
| 11.2 HONG KONG STUDY | 417 | ||
| 11.3 CONNECTICUT USA STUDY | 419 | ||
| 11.4 NEW ZEALAND STUDY | 420 | ||
| 11.5 SAN DIEGO, CALIFORNIA STUDY | 421 | ||
| 11.6 OTHER STUDIES | 423 | ||
| 11.7 CONCLUSIONS | 423 | ||
| REFERENCES | 426 | ||
| 12:\rEconomic evaluation | 429 | ||
| 12.1 INTRODUCTION | 429 | ||
| 12.2 ECONOMICS, ECONOMIC VALUES AND ECONOMIC EVALUATION OF INTERVENTIONS | 430 | ||
| 12.2.1 Cost/Benefit analysis | 432 | ||
| 12.2.2 Cost-effectiveness analysis | 433 | ||
| 12.3 VALUING THE BENEFITS OF INTERVENTIONS | 435 | ||
| 12.3.1 Human health benefits | 435 | ||
| 12.3.2 Other benefits | 437 | ||
| 12.3.3 Benefit valuation steps | 437 | ||
| 12.3.4 Economic valuation methods | 438 | ||
| 12.3.5 Recreational water quality valuation studies | 440 | ||
| 12.4 VALUING THE COST OF INTERVENTIONS | 444 | ||
| 12.4.1 Measuring costs | 444 | ||
| 12.5 CONCLUSIONS | 456 | ||
| REFERENCES | 457 | ||
| Index | 461 |