Parasitoses of the European bison caused by nematodes located in the large intestine

Abstract

Nematodes located in the large intestine of wild ungulates can induce weakness of animals as a consequence of a refractory and difficult to treat diarrhea, caused by invasion. We were encouraged to do the presented study becaus of the lack of current data about the invasion of mentioned nematodes in the European bison. The study was conducted in the Białowieża  Primeval Forest, during bison elimination in the winter seasons 2007–2010. 23 male and female bison were dissected during the study. The caecums of 14 bison aged ranging from 3 months to 16 years old were investigated as the most favourable location of the large intestine nematodes in the winter of 2007/2008. The whole large intestines, including caecum and colon of 9 bison aged ranged from 5 months to 10 years old were dissected parasitologically during the winter seasons in 2008/2010, in order to find out the detailed localization of the large intestine nematodes and the total intensity of invasion. 5 species of nematode, Trichuris ovis, Oesophagostomum venulosum, O. radiatum, Ashworthius sidemi and Nematodirus helvetianus, were found in dissected caecums of bison culled in winter 2007/2008. Moreover, all the bison investigated in the winter of 2009/2010 were infected with the species of nematodes mentioned above from the genus Trichuris and Oesophagostomum. The intensity of T. ovis invasion in the complete large intestines varied from 60 to 777 individuals and the mean intensity of that species was 368. The intensity of invasion of another found species, O. venulosum, varied from 37 to 289 individuals, whereas the mean intensity was 98. The intensity of O. radiatum, the other species of nematodes found in large intestine, varied from 1 to 809 individuals and the mean intensity of invasion was 122. The few additional species of nematodes were also found in the large intestine of the European bison. From 1 to 4 individuals of A. sidemi were found in the large intestine of 4 investigated bison. Moreover, 1 individual of N. roscidus was found in the single bison and 14 individuals in another one. The few individuals of B. trigonocephalum were also fund in two dissected bison. The intensity of the invasion of the nematodes of large intestine of the European bison in the Białowieża Primeval Forest remained on the comparable level throughout the last 20 years, however the number of species involved is increasing. The observed level of invasion is typical for subclinical parasitoses.