The genus Yersinia of the family Enterobacteriaceae includes the following 14 species: Y. pestis, Y. pseudotuberculosis, Y. enterocolitica, Y. frederiksenii, Y. kristensenii, Y. intermedia, Y. aldovae, Y. mollaretti, Y. bercovieri, Y. rohdei, Y. ruckeri, Y. aleksiciae, Y. massiliensis and Y. similis. Only Y. pestis, Y. pseudotuberculosis and Y. enterocolitica are considered to be human pathogens, although recent data suggest that some of the other species may also cause disease (Sulakvelidze, 2000). Y. enterocolitica and Y. pseudotuberculosis are recognised as food-borne pathogens and some large food-associated outbreaks of yersiniosis have been reported (Bottone, 1997). Y. enterocolitica is the species by far most frequently associated with human infections. Y. pseudotuberculosis infections are occasionally reported and most frequently observed in North-east Europe (Finland, Russia) and in Japan (Fukushima et al., 2001; Jalava et al., 2004). Yersiniosis in the United States has been characterized by a number of food-borne outbreaks in the 1980s, whereas in Europe and Japan most reported cases are sporadic (Schiemann and Wauters, 1992). In 2007 the incidence of confirmed cases of yersiniosis in Europe was 2.8 cases per 100000 population, with Lithuania, Finland and Sweden reporting the highest numbers of cases (16.8, 9.1 and 6.2 per 100000, respectively; EFSA, 2009). The disease can range in severity from self-limiting gastroenteritis to pseudoappendicitis, septicaemia in neonates and immunodeficient patients, and post-infection complications like reactive arthritis and myocarditis (Bottone, 1997). Though Y. enterocolitica was considered an emerging pathogen after the large outbreaks in the 1970s and 1980s, epidemiological data do not indicate an increase in sporadic cases or outbreaks of yersiniosis in the past two decades (Skovgaard, 2007).