[Forming of gastro-intestinal nematodes fauna of free ranging European bison in Bialowieza Primeval Forest during last 17 years (1984-2001)].

28 European bison of both sexes and in different age shot in Białowieza Primeval Forest in January 1984, (10 animals), January 1992 (10 animals) and in January and the beginning of February 2001 (8 animals) have been necropsied. The examined animals in mentioned years were of similar age. There were examined abomasa and duodena of shot animals. All necropsied bison were infected with gastro-intestinal nematodes. The highest intensity of infection with nematodes of abomasum was found in 1992 year and with nematodes of duodenum in 2001 year. In the examined period were found as many as 21 species of gastro-intestinal nematodes, and 15 of them occurred in 1984, 16 in 1992 and 17 in 2001; 12 species, namely: Trichostrongylus axei, T. capricola, Ostertagia ostertagi, O. lyrata, O. leptospicularis, O. kolchida, Spiculopteragia boehmi, Cooperia oncophora, Nematodirus helventianus, N. roscidus, N. europaeus and Aonchotheca bilobata occurred in all 3 examined years. The highest mean intensity of infection and the percentage index of intensity of these 12 species of nematodes showed O. leptospicularis which was 45% to 47% of all Ostertagiinae. Beyond of these 12 species of nematodes which occurred in all examined years, there were found 9 species more: Ostertagia antipini, Spiculopteragia mathevossiani, S. asymmetrica, Mazamastrongylus dagestanicus, Cooperia surnabada, C. punctata, C. pectinata, Haemonchus placei and Ashworthius sidemi. They occurred sporadically and in low density. During the examined period, bison have adapted 10 species of parasites from Cervides. Mazamastrongylus dagestanicus - parasite primary typical for moose, was for the first time found in bison.