Prevalence of pathogenic Yersinia enterocolitica and Yersinia pseudotuberculosis in wild boars in Switzerland

Between October 2007 and March 2008, 153 wild boars shot in the Canton of Geneva in Switzerland were sampled. Fifty-one percent of the animals were males and 49% were females. The age of most (81%) animals varied between 6 months and 2 years. Prevalence of enteropathogenic Yersinia in tonsils and faeces was studied using culture and PCR methods and in tissue fluid of tonsils using an ELISA system. Prevalence of anti-Yersinia antibodies in tissue fluid was 65%. Detection rate of enteropathogenic Yersinia in tonsils of 153 wild boars by real-time PCR was 44%. Ail-positive Yersinia enterocolitica and inv-positive Yersinia pseudotuberculosis were detected in 35 and 20% of the animals, respectively. Both species were detected in 10% of the animals. Isolation rate of enteropathogenic Yersinia was low; ail-positive Y. enterocolitica and inv-positive Y. pseudotuberculosis were found in 9 and 3% of the animals, respectively. Prevalence was shown to be significantly higher in tonsils than in faeces. Furthermore, females were more commonly positive than males. This study shows that the prevalence of enteropathogenic Yersinia is high and both enteropathogenic Y. enterocolitica and Y. pseudotuberculosis are common findings in tonsils of wild boars in Switzerland.