English summary: YERSINIA INFECTIONS IN FINLAND 1995-2005

Enteric yersiniosis is caused by Y. enterocolitica and Y. pseudotuberculosis. Acute enterocolitis is the most frequent manifestation of yersinia infection but postinfectious complications, most frequently nonpurulent arthritis, are common. Pork and pork products have been linked to yersinia infections. The role of other foods in the transmission of yersinia infection has been studied less. Y. pseudotuberculosis has been responsible for a local or regional outbreak in Finland almost every year, while Y. enterocolitica has usually caused sporadic infections. Isolation from a stool specimen is by far the method of choice for diagnosing Y. enterocolitica infection. Serological methods are used more often for diagnosing Y. pseudotuberculosis infections. The incidence of Y. enterocolitica has decreased in Finland during the last ten years, especially among young children under 5 years. Among school children and adults the decrease has been more moderate and among elderly people aged 75 or more the incidence has increased slightly. Y. enterocolitica infections were reported more often among adult women than men, but in other age groups no gender differences were found. Seasonal variation was small, the incidence being lowest during the winter months (December, January and February). The incidence of Y. enterorocolitica shows quite significant regional variation, which may be at least partly explained by differences in laboratory methods. Although their incidence has been decreasing, yersinioses are still almost twice as common as domestic salmonella infections.