Epidemiology of trichinellosis in lynx in Finland

Three hundred and twenty seven European lynx (Lynx lynx) were examined for Trichinella sp, larvae using the muscle digestion method. The animals were of both sexes, various ages, and collected between 1989 and 1994 in different locations in Finland. Forty percent of them (132) were found to be infected. Infection was overdispersed, so that the majority of infected lynx only harboured small amounts of larvae, while a minority had higher densities of infection, but never significantly exceeding 40 larvae per gram of muscle (lpg). The median density of infection was 1.04 lpg. To find factors statistically associated with the risk of infection, multivariate logistic regression analysis was performed. Male sex, increasing age, and the density of raccoon dog population in the area were all significantly associated with infection. However, the association with age was not linear and prevalence did not increase after middle age. The mean density of infection decreased slightly with age. The association with the density of the raccoon dog population leads to a tentative hypothesis that the raccoon dog might be an important reservoir of sylvatic trichinellosis in Finland.