Submitted to: American Society for Microbiology
Publication Type: Abstract only
Publication Acceptance Date: 2/27/2004
Publication Date: 5/23/2004
Citation: Wesley, I.V., Bhaduri, S., Bush, E. 2004. 5' fluorogenic PCR (real time) assays to determine the prevalence of Yersinia enterocolitica in U.S. market weight hogs [abstract]. American Society for Microbiology. p. 671. Interpretive Summary:
Technical Abstract: Background: Y. enterocolitica is a major human foodborne pathogen causing ~ 87,000 human cases and ~ 1,100 hospitalizations annually in the U.S. Hogs are a major reservoir. The purpose of this study was to estimate the prevalence of Y. enterocolitica in hogs and identify on-farm risk factors. Methods: Hogs on farms (n = 122) located in the 17 pork-producing states were sampled during National Animal Health Monitoring System (NAHMS) Swine 2000. Results: Tonsil (n = 1,218) and fecal (n = 2,847) swabs were screened for the ail gene, which encodes the adherence and invasion protein. For tonsils 10% (122 of 1,218 samples) were positive after irgasan tiracillin chlorate (ITC) enrichment, whereas 5.6% (68 of 1,218) were positive after subculture to the more selective cefsulodin-irgasan-novobiovin (CIN) agar. When tonsils were sampled to monitor the hog carrier status, the on-farm prevalence based on ITC data is ~ 32% (32 of 100 premises sampled), whereas the prevalence based on growth on CIN is ~ 20% (20 of 102 premises). When feces were used to gauge Y. enterocolitica prevalence, ~ 13% of hogs (372 of 2,847) harbored the ail gene after ITC enrichment. The overall on-farm prevalence is ~ 45.08% (55 of 122 premises), based on the detection of the ail gene in ITC broth enrichments of tonsils and feces. We correlated prevalence data with farm management practices and initially selected 12 factors (p < 0.25). Five factors were correlated with on-farm prevalence (p < .10): antibiotics in the feed (p = 0.07), previous history of vaccination for E. coli (p = 0.09), deaths due to scours (p = 0.07), failure of pigs to thrive because of the porcine respiratory distress complex (p = 0.07), and use of meat/bone meal in grower-finisher diet (p = 0.10). Ultimately, four factors were identified in the final regression model. These included, with their accompanying odds ratio (OR), location in a non-central state (OR = 0.3), vaccination for E. coli (OR 3.0), % deaths due to scours (OR 3.5), and presence of meat/bone meal in grower-finisher diet (OR 4.1).