Animal Waste, Water Quality and Human Health

4Animal Waste, Water Quality and Human HealthThis will be the second book in the series on “Emerging issues in water andinfectious disease” to deal with issues related to zoonoses; in part in recognitionof the fact that the majority, around 75%, of emerging and re-emergingpathogens are zoonotic. The first book, “Water-borne Zoonoses” (Cotruvo et al.2004), which complements this volume, focused on three questions:• The nature of waterborne zoonotic disease threats;• Identification of new disease candidates; and,• Adequacy of existing control measures.In contrast this volume focuses on:• The adequacy of the evidence base for policy;• The appropriateness and effectiveness of present regulatory responses; and,• Opportunities for effective low-cost regulation and management of actualand potential health risks.For the purposes of assessment, management and regulation, the issue consists ofthree principal components: the source (animal excreta), its transport (i.e. transferto, survival in and movement through watercourses); and resulting humanexposure. All three can be the object of interventions.This report, therefore, reflects on understanding what are the assessment,managerial and regulatory challenges, the adequacy of present regulatoryapproaches, and the characteristics of a better system.For bathing waters the established approach was, for many years, retrospectivecompliance testing on an annual basis. However the 1999 “Annapolis Protocol”(WHO, 1999), associated World Health Organization’s Guidelines (WHO2003; 2006) and their implementation in associated developments (EU,New Zealand 2003) show a strong shift towards prevention and real-timesupport for informed decision-making by members of the public. Thesedocuments also recognize, however, that health risks from zoonotic sources inabsolute terms or as compared with faecal indicators are inadequatelyunderstood and they are cautious in interpreting the associated risks, except inassuming that the risk presented by animal excreta is less than that fromhuman excreta.For drinking-water the shift to preventive management is more advanced, withdetectable changes in regulation and/or practice since the publication of the thirdedition of WHO’s Guidelines for Drinking-water Quality which recommended a“Framework for Drinking-water Safety” and associated “Water Safety Plans”(WHO 2004, reconfirmed in the fourth edition, WHO 2011). However, problemsremain of inadequate understanding of zoonotic risks and the inadequacy of faecalbacteria as indicators of risk.