The potential risk associated with foodborne pathogens from dairy herds in a watershed.

摘要

The purpose of this project was to provide information about several food- and water-borne bacterial pathogens among dairy cattle in Delaware County. A number of complementary studies were performed in order to achieve the following aims: 1. Establish protocols for pathogen detection in bovine fecal samples with the BAX Automated PCR System. 2. Determine prevalence of top-ranked foodborne pathogens in dairy herds in a watershed. 3. Identify risk factors associated with the presence of these zoonotic bacteria on farms. The pathogens of concern in these studies were Salmonella, E. coli O157:H7, and Campyobacter species.;A study was performed to assess the validity of the Dupont Qualicon BAX automated Polymerase Chain Reaction (PCR) system to detect the shedding of Salmonella species in bovine fecal samples. Using culture as the gold standard test, the BAX system was found to have a sensitivity of 85.7% and a specificity of 90.5%. There was excellent agreement (kappa = 0.71, standard error = 0.072) and no significant differences between the two methods (McNemar's Chi square = 0.180).;A repeat cross-sectional study was performed to assess the occurrence of Salmonella spp. in dairy herds in a watershed and to determine the factors that play a role in the likelihood of perpetuation of this organism among animals on these farms. Salmonella was detected in 1.7% of animals and 44% of the herds. Risk factors that were found to be associated with the presence of the pathogen on the farm in the final multivariate logistic regression model included calf flooring material, calf access to the dam, and the presence of a designated calving pen.;An additional repeat cross-sectional study was performed to assess the prevalence of E. coli O157:H7 and risk factors associated with its presence on dairy farms in the watershed. E. coli O157:H7 was detected in 74% of the herds in the target population and in 3.7% of samples collected. Risk factors that were found to be associated with the increased likelihood of the pathogen on the farm included decreasing age, housing calves indoors, group housing for calves, housing calves in the calf barn, presence of dogs on the farm, and housing post-weaned calves in a cow barn or heifer barn versus a greenhouse.;A final repeat cross-sectional study was performed to determine the prevalence of and risk factors associated with 3 species of Campylobacter on the farms in the watershed. Campylobacter was detected in 85% of the herds in the target and in 5% of samples collected. Of all the samples positive for Campylobacter species, C. jejuni was detected in 81% of samples, C. coli in 16% of samples, and both of these species in 3% of samples, while C. lari was not detected in any samples. Risk factors that were found to be significantly associated with increased odds of detecting Campylobacter included decreased age, seasonality, housing calves in the cow barn, housing calves individually, and lack of horses on the farm.