This study tracked the incidence and transmission of foodborne and waterborne pathogens on organic dairy farms and developed recommendations for practices to minimize foodborne illness risks. Milk, milk filter, and fecal samples were collected from 27 organic and 68 conventional dairies and tested for six bacterial pathogens: Escherichia coli, Salmonella, Listeria monocytogenes, Campylobacter, Staphylococcus aureus, and Klebsiella.pneumoniae. Feces were also tested for the protozoan parasites Giardia and Cryptosporidium. Additional data was collected to identify pathogen sources, ecological and management factors, and critical control points to mitigate food safety risks.

Samples were handled by Extension to maintain anonymity. Participating farmers received results and were offered the option of further investigation to identify the source of any pathogens identified in the initial testing. On organic farms, 80% of composite samples showed S. aureus, 48% E. coli, 19% Salmonella, 15% L. monocytogenes, and 4% Cryptosporidium. On conventional farms, 62% of composite samples showed E. coli, 48% S. aureus, 37% Salmonella, 12% L. monocytogenes, 3% Campylobacter, and 15% Cryptosporidium. Milk filters were twice as likely to show pathogens as bulk tank milk samples. Four farms requested additional testing of individual cows to track Campylobacter.