Animal Waste, Water Quality and Human Health

Summary statementix▪▪▪▪▪the contribution by the human population. The faecal production rate andcontribution to the environment of these animals can be as high as 2.62 ×10 13 Kg/Year * .Limiting zoonotic pathogen-shedding in farm or production facilities fordomestic animals should be accomplished by preventing illness inlivestock, through minimizing exposure to pathogens, by increasingimmunity, by manipulation of the animal gastrointestinal tract microbialecology and by managing (including treating) animal waste to reduce therelease of zoonotic pathogens into the environment.The carrier status of animals, particular for the protozoan parasites, appears topeak in very young animals, while in the entire animal population thephenomenon of “super-shedders” provides a possible handle on reducingoverall pathogen loads in the environment, provided reliable and costeffectivetechniques are developed for timely detection of super-shedders.Rivers and streams deliver faecal wastes (and the zoonotic pathogens theymay contain) to surface water bodies used for recreation, commercialshellfish harvesting and as sources of drinking-water. The transport offaecal material and the fate of zoonotic pathogens in a catchment is notunderstood with a great degree of certainty. Modeling is the greatest sourceof the information in this area and has the potential to be further developed.In the context of animal husbandry four control points exist: minimizingexposure of livestock to pathogens, increasing reservoir host immunityand resistance, manipulation of the microbial ecology of the host’sgastro-intestinal tract and treatment of animal wastes to reduce zoonoticpathogens. Raising pathogen-free animal herds or flocks as well astreatment of animal waste through composting and anaerobic digestion athigh temperatures have proved feasible and effective but, at aconsiderable cost. Animal vaccination and manipulating the host animal’sintestinal flora have met with mixed success.The most effective management practices in catchments are at the farm orproduction facility. Their overall purpose is to reduce pathogen transferfrom their sources to a watercourse and they should be evaluated andoptimized to that end. Manures can be intercepted and stored in ponds,contaminated water can undergo on-farm treatment and constructed farmwetlands can be used to reduce pathogen load. Bridging and fencing canbe used to control livestock near streams. Managing the spatialdistribution of animals can avoid the build-up of high concentrations ofcontamination in sensitive areas.*http://faostat.fao.org