[Large-intestinal nematoda in bison].

Area of Science:

• Veterinary parasitology
• Wildlife ecology
• European bison (Bison bonasus) health

Background:

• Parasitic infections pose a significant threat to wildlife populations, impacting health and survival.
• Understanding nematode prevalence and intensity in European bison is crucial for conservation efforts.
• Seasonal variations in habitat and feeding influence parasite transmission dynamics in large herbivores.

Purpose of the Study:

• To investigate the species composition and prevalence of gastrointestinal nematodes in European bisons.
• To assess the impact of wintering on bison parasitological status.
• To compare parasite loads between free-ranging and captive bison populations.

Main Methods:

• Parasitological autopsies of large intestines from European bisons.
• Dissections conducted at the beginning and end of winter seasons (1987-1988).
• Identification and quantification of nematode species: Chabertia ovina, Oesophagostomum radiatum, Oe. venulosum, and Trichocephalus ovis.

Main Results:

• Four nematode species were consistently found: C. ovina, O. radiatum, Oe. venulosum, and T. ovis.
• At the end of winter, C. ovina showed high prevalence but low intensity.
• Oe. radiatum, Oe. venulosum, and T. ovis exhibited increased extensity and intensity of infection.
• Free-ranging bisons showed higher assimilation of Oe. venulosum and C. ovina compared to captive bisons.

Conclusions:

• Wintering conditions, particularly accumulated feces and contaminated hay, likely serve as a primary source of nematode invasion.
• Seasonal changes significantly affect nematode infection dynamics in European bisons.
• Management strategies should consider parasite transmission risks associated with winter feeding and habitat use.