Epidemiological study of Yersinia enterocolitica in swine herds in Quebec

The objectives of this study were the identification of the different conta mination sources of Yersinia enterocolitica, as well as the determination o f the prevalence and the distribution of the different genotypes in swine h erds. The owners of 20 farms, located in the Richelieu-Yamaska region, agre ed to participate in the study. Each farm was visited a minimum of 5 times between May and October 1997, and, at each visit, 20 environmental and 10 f ecal samples were collected. Yersinia enterocolitica isolates were identifi ed, serotyped, and submitted to a genetic characterization by pulsed-field gel electrophoresis. The correlation coefficient (0.61) between prevalence in environment and in feces was significant (P = 0.004). Among the 153 posi tive samples, 93.5% belonged to serotype 0:3. The comparison of PFGE profil es revealed that all environmental Y. enterocolitica isolates had a profile identical to that of isolates recovered in feces from the corresponding fa rms. Also, when the genetic profiles of isolates recovered from feces colle cted at the first visit were compared with the profiles of isolates obtaine d from the subsequent visits, the same profile was observed on every farm. We concluded that environment does not represent the main source of contami nation of swine by I: enterocolitica and that, in most instances, the same strain persists in a barn from one production lot to another.