Aspects of the epidemiology of Yersinia enterocolitica: a review

A review of works concerning different aspects of the epidemiology of human pathogenic Yersinia enterocolitica biogroup IV/serogroup O:3 (Y. enterocolitica O:3) is given. To investigate the epidemiology of Y. enterocolitica O:3 in Danish herds of pigs, tonsil swabs from 2218 freshly slaughtered pigs originating from 99 herds were examined. The organism was isolated from 25% of the pigs and from 82% of the herds. No herd management factor could be associated with the presence of the organism. The effect of slaughtering technique on surface contamination with Y. enterocolitica O:3 was investigated. 1256 pigs were slaughtered by different evisceration techniques. When a mechanical bung cutter was used instead of the traditional, manual evisceration the contamination was reduced markedly, especially when the rectum and anus were enclosed in a plastic bag prior to the removal of the gut. It was possible to reduce the rate of the surface contamination from 26% on the medial hind limb and 13% on the split sternum and surroundings to about 2% for both sampling sites. An investigation of the presence of Y. enterocolitica O:3 in meat and meat products in retail butcher's shops was performed. The organism was detected in 10 of 33 samples of minced pork and in three of 24 samples of minced beef, but in none of 32 samples of sliced vacuum packed, low to medium salt meat products. The positive minced beef samples were collected at butcher's shops from which positive samples of minced pork were found as well. It is concluded that Y. enterocolitica O:3 is common in pork with a risk of cross-contamination to other products for example ready-to-eat meat products that might be a source of human infection.