Objective:
Objective 1 - Determine the environmental compartments within dairy farming systems that support the survival of the zoonotic pathogens Salmonella enterica, Escherichia coli, and Listeria monocytogenes and characterize their contribution to the pathogen content of milk. Objective 2 - Characterize the role of management practices in the introduction and maintenance of Salmonella enterica, Escherichia coli, and Listeria monocytogenes on dairy farms and evaluate changes in management practices that might reduce or eliminate pathogens. Objective 3 - Use molecular typing methods to determine the relationship between isolates of Listeria, Salmonella, and pathogenic E. coli from dairy cows, the farm environment, and from bulk tank milk with those known to have caused human disease. Objective 4 - Develop new methods for the rapid and sensitive detection of Bacillus anthracis and Listeria monocytogenes in bulk tank milk and milk products.

Approach:
Although pasteurization and regulations controlling the processing of any products made with unpasteurized milk have an excellent record of assuring the biological safety of dairy products marketed in the US, there is increasing concern about the presence of zoonotic pathogenic microorganisms in raw milk. For various cultural and economic reasons the consumption of raw milk and desire for products made from raw milk seems to be increasing and outbreaks of food-borne gastrointestinal disease due to contamination of dairy products have been documented. This project focuses on the ecology of the zoonotic bacterial pathogens Salmonella, Listeria monocytogenes, and Escherichia coli on dairy farms in the Northeastern United States, and the relationship of the pathogens found in farm animals and the farm environment with those found in bulk tank milk from those farms. Intensive longitudinal sampling will be performed on three `typical¿ farms with collection of milk, milk filters, blood, feces, and various environmental samples. We will analyze samples for the three pathogens by both molecular and culture techniques; collaborators will analyze samples for MAP, Campylobacter, and enterococci. Molecular characterization techniques will be used to equate any pathogens found in bulk tank milk with those found on the farm. Management changes will be suggested to the farmers and the results of those changes will be documented. The relationships between Listeria monocytogenes from the farm and those associated with human disease will be investigated. Methods will be developed for improved detection of bacterial pathogens in milk and environmental samples.