The research aims to estimate the prevalence of Salmonella, Shiga toxin-producing E. coli and Campylobacter in human patients with diarrhea, in ruminants to be slaughtered and meat from these animals at retail. Furthermore at farm level the presence of these pathogens in ruminants will be examined and correlated with the presence of diarrhea in persons living on the farms. Characterization of the collected strains may allow to link the presence of these pathogen in ruminants and the development of diarrhea in humans. At the slaughterhouse level sources for carcass contamination will be examined. The latter data will be used to formulate preventive measures reducing the carcass contamination.