Contamination of freshly slaughtered pig carcasses with human pathogenic Yersinia enterocolitica

Evidence is presented for the extent of contamination of freshly slaughtered pig carscasses with human pathogenic Yersinia enterocolitica and shows the significance of faecal contamination as a source of infection. Swab samples collected from the rectum and the surface of a total of 1458 pig carcasses were examined for the presence of human pathogenic Y. enterocolitica. Y. enterocolitica, biovar IV, serogroup 0:3, were isolated from the rectum of 360 pigs (24.7%). The organism was isolated from carcass surfaces with varying frequencies depending on the evisceration technique. Manual evisceration was found to correspond with high frequencies of contamination: 26.3% on the medial hind limb and 12.9% on the split sternum. The use of a mechanised bung cutter was found to reduce the rate of contamination, especially when the bung cutter was used in connexion with enclosing the anus and rectum in a plastic bag to minimise faecal contamination. When carcasses were eviscerated in this way, it was possible to reduce carcass contamination to 1.9% on the medial hind limb, 1.0% in the pelvic duct, and 2.2% on the split sternum.