Gastrointestinal parasites in an isolated Norwegian population of wild red deer (Cervus elaphus)

Authors: DAVIDSON, REBECCA - Norwegian Veterinary Institute; KUTZ, SUSAN - University Of Calgary; MADSLIEN, KNUT - Norwegian Veterinary Institute; Hoberg, Eric; HANDELAND, KJELL - Norwegian Veterinary Institute

Submitted to: Acta Veterinaria Scandinavica
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/31/2014
Publication Date: 10/8/2014
Publication URL: http://doi:10.1186/s13028-014-0059-x
Citation: Davidson, R., Kutz, S., Madslien, K., Hoberg, E.P., Handeland, K. 2014. Gastrointestinal parasites in an isolated Norwegian population of wild red deer (Cervus elaphus). Acta Veterinaria Scandinavica. 56:59.

Interpretive Summary: Documentation of faunal diversity for parasites in ungulates is an essential step in developing an understanding of the factors that determine geographic distributions, host associations and patterns of disease. Baselines for diversity and species richness are essential in recognizing and predicting responses to accelerating climate change and environmental perturbation that create the potential for faunal mixing and the exchange of parasites among assemblages of hosts. Helminth parasite diversity was assessed in a closed and isolated, high-density population of red deer in coastal Norway. The helminth fauna among sampled red deer was enumerated and species were identified based on morphology and included: Ostertagia leptospicularis/O. kolchida, Spiculopteragia spiculoptera/ S. mathevossiani and T. axei in the abomasum of hosts. Characterisation of the intestinal parasite fauna revealed Capillaria bovis, Cooperia oncophora, Oesophagostomum venulosum, Trichuris globulosa and tapeworm fragments (presumed anolocephalids) in seven individuals. No significant age related trends were seen, with yearlings, with the exception of higher intensity of infection of T. axei relative to other age classes. Assessment of abomasal parasite burden and body condition revealed no significant trends, althouhg helminth abundance exceed levels observed in other areas of Europe and North America. In calves, correlation between increased parasite burden and decreased slaughterweight was seen, although the significance level was not reached, whilst the opposite was seen in adults with the heaviest adults exhibiting the higher burdens. The parasite burden was aggregated with three adult red deer harbouring 75% of the total abomasal parasite count. Norwegian red deer are parasitized by a reduced subset of gastrointestinal nematodes typical of this cervid across an extensive geographic range in Eurasia. These data are the first to explore helminth diversity in Norweigan red deer. An initial baseline is provided for understanding the potential for host-switching events by parasites among other cervids or domestic ungulates, an expected outcome of habitats in transition and geographic expansion for red deer. Results are of importance to wildlife biologists and managers, veterinarians, and conservation biologists in Europe and North America in revealing and mitigating the impacts of environmental change.

Technical Abstract: Thirteen red deer, culled from the isolated population at the Mongstad Oil Refinery, were investigated for gastrointestinal helminths. These animals, enclosed by the refinery fence, do not have contact with other ruminants and have a high population density considering the available browsing area (1km2) within the refinery site (3km2). The population was estimated to be 110-130 at the time of culling. The helminth fauna among these sampled red deer was enumerated and species were identified based on morphology. Ostertagia leptospicularis/O. kolchida was detected in 83% [CI 55-95%], Spiculopteragia spiculoptera/ S. mathevossiani in 92% [CI 65-99%] and T. axei in 42%, [CI 19-68%] of the abomasa examined. Characterisation of the intestinal parasite fauna revealed Capillaria bovis, Cooperia oncophora, Oesophagostomum venulosum, Trichuris globulosa and tapeworm fragments (presumed anolocephalids) in seven individuals. Only one calf had an infection with more than one small intestinal helminth (tapeworm fragment and Trichuris globulosa). The remaining deer had single species intestinal infections. No significant age related trends were seen, with yearlings, with the exception of higher intensity of infection of T. axei relative to other age classes. Assesment of abomasal parasite burden and body condition revealed no significant trends. In calves, correlation between increased parasite burden and decreased slaughterweight was seen, although the significance level was not reached, whilst the opposite was seen in adults with the heaviest adults exhibiting the higher burdens. Given the small sample size, just thirteen animals, the trends that were seen need further investigation. The parasite burden was aggregated with three adult red deer harbouring 75% of the total abomasal parasite count. Norwegian red deer are parasitized by a reduced subset of gastrointestinal nematodes typical of this cervid across an extensive geographic range in Eurasia.