EN
A disease of the genital organs of male European bison (Bison bonasus) at the Białowieża primaeval forest has been noted since 1980. Among 63 eliminated bisons 25 males have had lesions on the penis and prepuce. Oedema of the prepuce and cutaneous fistulas of the abdominal wall were confirmed. Necropsy showed nodular to diphtheroid-necrotic inflammatory lesions of the superficial and deep layers of tissues. Virologic and serologic studies were negative for IBR/IPV. Corynebacterium sp, Bacillus sp. and Fusobac- terium necrophorum were isolated from the lesions. Parasitism was confirmed in a majority of the bison, especially young individuals up to 3 years. These were invasions of gastro-enteric and pulmonary helminths as well as liver flukes. Twenty seven of 63 bisons were shown to have Trypanosoma sp. Haematologic studies of 14 males showed anaemia and lowered serum carotine levels in 10 male bisons.