Introduction
Fecal wastes from domestic animals, wildlife and humans are applied to the soil surface and to varying extents are incorporated into the soil. These fecal wastes can also enter water systems by direct contamination of the water or through seepage or surface runoff. Humans contaminate water sources through poorly processed sewage effluents, malfunctioning septic tanks and seepage from sanitary landfills. Domestic and wild animals contaminate water by defecation in
unprotected surface water, through runoff and as a result of seepage of water through soil that contains an excessive amount of animal feces. A wide variety of pathogenic viruses, bacteria and parasites may be found in the feces of wild and domestic animals and humans. Also, nonpathogenic bacteria and parasites are found in large numbers in the feces of animals as well as soil and water. Only a small number of animal pathogens in feces, water and soil have the potential to infect humans and domestic animals (Table 1). These are the pathogens that are of great concern to the public, who are usually exposed to these animal pathogens through consumption of fecal contaminated food or water. Concentration of wildlife is also a potential source of water and soil contamination. Some types of wildlife congregate in herds and flocks and can contribute to extensive pathogen contamination to the water and soil in certain location and times of the year. Bacterial, parasitic and viral pathogens in human fecal waste have the greatest potential to cause infection in other humans. Raw sewage is processed to varying degrees before it is distributed on soil or discharged into water systems. Failure to appropriately process human sewage probably poses the greatest threat to human health however it is often impossible to identify sources of
food and water contamination. Animal feces may contain pathogens infectious to both humans and animals. As a result food animals are incriminated in many waterborne and foodborne outbreaks. It is critical for human health, animal health and agriculture sustainability reasons that water and food supplies be protected from contamination by animal feces.