Not necessarily. All of the bacterial pathogens and protozoan parasites found in animal manures can also be found in the feces of many other mammals, birds, and some reptiles. The contribution from other sources will, in large measure, be dictated by predominant land uses in conjunction with management practices and/or infrastructure. For example, all of the pathogens/parasites of concern can be found in human sewage (obviously), while a number of these organisms also cause disease in companion animals (i.e., dogs, cats). Consequently, leaky septic systems or sewer lines, storm runoff, and/or outflows from waste water treatment plants are all potential sources of pathogens/parasites in watersheds containing urban centers.
Although information is limited, studies suggest that wildlife (e.g., deer, beaver, waterfowl) also shed many pathogens/parasites and therefore contribute to the contamination of watersheds.
In summary, livestock are likely to be a primary source of pathogens in watersheds where livestock production is the predominant land use, particularly where animals have access to surface waters and/or manures are applied to land near surface waters. Recent studies suggest, however, that in urban as well as forested watersheds, wildlife may be the predominant source of microbial contamination.
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