PIGS INTENDED FOR SLAUGHTER AND PORK AS SOURCES OF PATHOGENIC YERSINIA ENTEROCOLITICA

During a period of eight months, samples of carcasses, tonsils, tongues and rectal swabs were taken in four pig slaughter halls. Porcine head meat was sampled in a meat products factory and samples of minced pork were taken in butcher's shops. Pathogenic strains of Yersinia enterocolitica (serological groups 0:3, 0:9 and 0:5.27) were isolated from 36 (42 per cent) of 86 porcine tonsils, 8 (20 per cent) of 40 tongues, 17 (17 per cent) of 100 rectal swabs and from 4 (1 per cent) of 400 pork samples. Pathogenic strains of Yersinia were not isolated from samples of 210 pig carcasses and from 20 samples of porcine head meat. These results confirm that pigs are an important reservoir of pathogenic Y. enterocolitica. However, contamination of carcasses during the process of slaughter with Yersinia from either faecal material or from the tonsillary region does not seem to occur frequently, which may also explain the low rate of contamination with pathogenic Y. enterocolitica observed in pork. As pork is rarely contaminated with pathogenic Y. enterocolitica, the possibilities for growth of these organisms in raw pork are limited, the minimum infective dose is probably high and pork is usually not eaten raw, it is not likely that pork is an important source of yersiniosis in the Netherlands.