[On the occurrence of the nematode Oswaldocruzia filiformis (Strongylida: Molineidae) in Karelia].

Contents of the intestines of the viper Vipera berus (L., 1758) from Kizhi archipelago (Lake Onego) was examined. Helminth fauna of the viper was found to include single nematode species, Oswaldocruzia filiformis Goeze, 1782 (Strongylida: Molineidae). Prevalence of the invasion was 60%, intensity of the invasion was 1-8 specimens per host, index of abundance was 1.92 specimens. Measurements and pictures of the parasite are given. Morphometric data on the nematode from viper are compared with those from other host species.