Submitted to: American Association of Swine Veterinarians Annual Meeting
Publication Type: Proceedings
Publication Acceptance Date: 9/5/2003
Publication Date: 3/6/2004
Citation: ROSTAGNO, M.H., HURD, H.S., MCKEAN, J.D. ARE THERE HIGH AND LOW SALMONELLA PREVALENCE FARMS?. PROCEEDINGS OF THE AMERICAN ASSOCIATION OF SWINE VETERINARIANS ANNUAL MEETING. 2004. P. 445-446.
Technical Abstract: Pork and pork products constitute one of the sources of non-typhoidal salmonellosis for humans. To reduce the number of Salmonella-infected pigs entering the slaughterhouse, pre-harvest intervention and control measures are necessary. However, in order to evaluate potential interventions and control measures, an in depth understanding of the on-farm S. enterica epidemiology is essential. The identification of high and low prevalence farms will allow case-control studies. Therefore, the objective of this study was to determine how consistent is the S. enterica prevalence within finishing pig sites. In each of the 5 sites studied, 5 finishing pig loads were sampled 2-3 days prior to slaughter (n = 30 samples/load). Samples consisted of individual fecal material (10 g) collected directly from the rectum. Samples were enriched in Tetrathionate and Rappaport-Vassiliadis broths for the detection of S. enterica by an antigen-capture enzyme-linked immunosorbent assay (ELISA). All studied sites were Salmonella-positive in at least one sampling. The overall prevalence of pigs infected with S. enterica was 10.9% (95% C.I. 2.6 - 19.2%). The comparison of the overall prevalences found by site (after 5 samplings) revealed statistical differences between sites, allowing their categorization. However, a striking observation in this study consisted in the wide variation in the S. enterica prevalence of different finishing pig loads within individual sites. The overall S. enterica prevalence in each studied site (followed by the respective lower and higher prevalence found) was: 10% (0 and 26.7%) in site 1; 8% (3.3 and 13.3%) in site 2; 19.3% (3.3 and 40%) in site 3; 2% (0 and 10%) in site 4; and 15.3% (0 and 43.3%) in site 5. Based on the results of this study, it can be concluded that S. enterica prevalence varies between finishing pig loads within the sites, making difficult the categorization of high and low S. enterica prevalence sites, based on a single sampling (or point estimates).