Prevalence And Transmission Routes Of Yersinia Enterocolitica In Pigs Of China

Yersinia enterocolitica is a zoonotic pathogen widely distributed in nature(5). Pigs are considered to be the primary reservoir of human pathogenic Y. enterocolitica strains in the world, slaughtered pigs are one of the potentially important sources for the infection (14,24,31,35,40). In order to study the distribution of Yersinia enterocolitica in pigs in China, we selected abattoirs, pig pens and farms from eleven different provinces of China (Middle-Henan; Southwest-Sichuan, Yunnan; North-Beijing, the Inner Mongolia Autonomous Region, Tianjin; Northeast-Heilongjiang; Northwest-the Ningxia Hui Autonomous Region, Qinghai and East-Jiangsu, Jiangxi) to collect a total of8,773samples during Mar2009to Nov2011. Of these,4,495were oral-pharyngeal swab (tonsils) samples from pigs,1,239were from intestinal contents and3,039were feces samples from abattoirs or local pigpens. The data showed1,132strains were obtained, where the isolation rate for Yersinia enterocolitica was19.53%(878/4,495) from the tonsil samples,7.51%(93/1,239) from intestinal contents, and5.30%(161/3,039) from feces. Of the850pathogenic Yersinia strains, except for three 2/O:9and three4/O:3, the others844/850were all bioserotype3/O:3. It is obviously that O:9has been replaced by O:3serotype to be the main serotype of pathogenic Yersinia enterocolitica in China. Interestingly, pathogenic Y. enterocolitica accounted for the majority of the isolated strains from most provinces (85.17%-100%), whereas from Heilongjiang,96.52%(111/115) were classified as nonpathogenic biotype1A with various serotypes and only3.48%of the strains (4/115) were pathogenic3/O:3. All of the pathogenic strains were analyzed using pulsed-field gel electrophoresis (PFGE), and49patterns were obtained for the O:3pathogenic strains, most of them were K6GN11C30021(53.13%:450/847) and K6GN11C30012(21.37%:181/847). Every region had a primary pattern, besides, several diarrhea patients’ samples showed PFGE patterns identical to the samples from local pigs, suggesting a link between porcine isolates and human infection. The constitute of PFGE patterns of pathogenic Yersinia enterocolitica in patients is similar in the constitute of pigs and dogs but is not quite the same in other animals.Our research suggested the prevalence of Yersinia enterocolitica in pigs of China was high, and was characterized regionally. The similar PFGE patterns confirmed that strains isolated from pigs are closely related to strains from human infections. The pig farms and slaughterhouses are widely distributed in China and people eat pork and products a lot, so we should prevent humans, other animals and environmental infection the pathogenic Yersinia enterocolitica carried by pigs.