Manure and Microbes: Public and Animal Health Problem?

Most environmental concerns about waste management either have focused on the effects of nutrients, especially N and P, on water quality or have emphasized odor problems and air quality. Microbes from manure are often low on the priority list for control and remediation, despite the fact that several out-breaks of gastroenteritis have been traced to livestock operations. The pathogens discussed in this paper include protozoans (Cryptosporidium parvum, Giardia spp.), bacteria (Listeria monocytogenes, Escherichia coli O157:H7, Salmonella spp., and Mycobacterium paratuberculosis), and some enteric viruses. Clinical symptoms, prospects for zoonotic infection, and control methods other than the use of antimicrobials are considered. Recommendations to avoid disease transmission include taking steps to ensure the provision of clean, unstressful environments to reduce disease susceptibility and the careful handling and spreading of manure from animals at high risk for infection, especially young calves. Composting and drying of manure decrease the number of viable pathogens. Environmental controls, such as filter strips, also reduce the risk of water contamination.