APMIS zyxwvutsrqponml 108: 8144. 2000 Printed zyxwvutsrqpon in Denmark zyxwvutsrqponm . All righis reserved Copyrixht zyxw 0 APMIS 2000 ISSN 0903-4641 zyx An zyxwv outbreak of trichinellosis in farmed wild boar in Finland zyx L. OIVANEN.’,2 T. MIKKONEN2 and A. SUKURA* ’National Veterinary and Food Research Institute, Helsinki and ’Department of Basic Veterinary Sciences, Faculty of Veterinary Medicine, University of Helsinki, Finland Oivanen L, Mikkonen T & Sukura A. An outbreak of trichinellosis in farmed wild boar in Finland. APMIS 2000; 108: 8 14-8. Nine farmed wild boar out of 25 slaughtered from a single farm were condemned at meat inspection because of trichinellosis. With RAPD-PCR, Trichinella spiralis was identified in all positive wild boar. Out of the available serum samples (n=7), all wild boar which had failed the meat inspection showed seroconversion in ELISA and Western blotting, as did one additional animal which had passed the inspection. The animals became infected during an invasion of rats from an improperly closed dump near the farm. Unfortunately, by the time trichinellosis was discovered in the wild boar, the invasion had already been brought under control; thus, no samples from rats were available. However, having lived through the rat invasion was shown to be a risk factor for trichinellosis in wild boar (relative risk, RR=6.3). In wildlife samples from surrounding areas, sylvatic trichinellosis was found to be very common (74%; n= 19 red foxes). Intriguingly, the prevalent species in trichinella-positive foxes differed from that in wild boar, Trichinella nativa and zyxwvu T. spiralis being found in 12 foxes and in one fox, respectively. Key words: Trichinella; trichinellosis; game farms; wild boar; epidemiology; Finland. Leena Oivanen, Faculty of Veterinary Medicine, University of Helsinki, PO. Box 57, FIN-00014, Finland. e-mail: Leena.Oivanen@helsinki.fi In Finland, trichinellosis is found during meat inspection of domestic pigs, farmed wild boar, and wild game. The prevalence of trichi- nellosis in domestic pigs is very low (0.004%), but is higher in farmed wild boar (1%) (1). In addition, trichinellosis is quite common in wild predators in the southern part of the country. In recent years, prevalence rates of 40% in European lynx (Lynx lynx) (2), 50% in raccoon dogs (Nyctereutes procyonoides) (3) and 50% in red foxes (Vulpes vulpes) from southern Finland have been recorded, in con- trast to in the northern Finland, where only Received June 23, 2000. Accepted October 30, 2000. 4% of foxes are infected (National Veterinary and Food Research Institute EELA, Helsinki, 1997-1998, unpublished). Wild boar, Sus scrofu, are found in Finland as sylvatic game and farmed animals. The wild population is fairly small, consisting of only a few hundred individuals. Each year no more than 70 animals are bagged by hunters. The farmed population is more numerous (4); the number of wild boar farms is currently estimated to be be- tween 60 and 80. The largest farms have 200-300 animals, the smallest less than 10. In 1999, the number of slaughtered wild boar was 1000. Farmed wild boar are typically kept as herds in fenced forest areas, where they are in close con- tact with the surrounding wildlife. 814