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Yersinia enterocolitica is an important food-borne pathogen that can cause yersiniosis in humans and animals. The epidemiology of Y. enterocolitica infections is complex and remains poorly understood. Most cases of yersiniosis occur sporadically without an apparent source. The main sources of human infection are assumed to be pork and pork products, as pigs are a major reservoir of pathogenic Y. enterocolitica. However, no clear evidence shows that such a transmission route exists. Using PCR, the detection rate of pathogenic Y. enterocolitica in raw pork products is high, which reinforces the assumption that these products are a transmission link between pigs and humans. Several different DNA-based methods have been used to characterize Y. enterocolitica strains. However, the high genetic similarity between strains and the predominating genotypes within the bio- and serotype have limited the benefit of these methods in epidemiological studies. Similar DNA patterns have been obtained among human and pig strains of pathogenic Y. enterocolitica, corroborating the view that pigs are an important source of human yersiniosis. Indistinguishable genotypes have also been found between human strains and dog, cat, sheep and wild rodent strains, indicating that these animals are other possible infection sources for humans.

Wild boars as an important reservoir for food-borne pathogens Abstract One hundred fifty-three wild boars shot in the canton of Geneva, Switzerland, were studied for the occurrence of foodborne pathogens. Tonsils and fecal samples of the animals were examined using real-time polymerase chain reaction, enzyme-linked fluorescent immunoassay, and cultural methods. The detection rate of Salmonella spp., Yersinia enterocolitica, Yersinia pseudotuberculosis, stx-positive Escherichia coli, and Listeria monocytogenes was 12%, 35%, 20%, 9%, and 17%, respectively, when tonsil samples were studied. Only Y. enterocolitica (5%) and L. monocytogenes (1%) were detected in fecal samples. None of the samples was positive for Campylobacter spp. Females (71%) and young animals (61%) carried more frequently one or more pathogens than males (53%) and older ones (44%). In total, 8 Salmonella spp., 14 Y. enterocolitica, 4 Y. pseudotuberculosis, and 26 L. monocytogenes strains were further characterized. Most of the Salmonella spp. strains were of serotype Salmonella Enteritidis (75%) followed by serotypes Salmonella Stourbridge (13%) and Salmonella Veneziana (13%). L. monocytogenes strains belonged to serotypes 1/2a (42%), 1/2b (19%), and 4b (38%). One hundred fifty-three wild boars shot in the canton of Geneva, Switzerland, were studied for the occurrence of foodborne pathogens. Tonsils and fecal samples of the animals were examined using real-time polymerase chain reaction, enzyme-linked fluorescent immunoassay, and cultural methods. The detection rate of Salmonella spp., Yersinia enterocolitica, Yersinia pseudotuberculosis, stx-positive Escherichia coli, and Listeria monocytogenes was 12%, 35%, 20%, 9%, and 17%, respectively, when tonsil samples were studied. Only Y. enterocolitica (5%) and L. monocytogenes (1%) were detected in fecal samples. None of the samples was positive for Campylobacter spp.