Diversity of gastrointestinal helminths in Dall's sheep and the negative association of the abomasal nematode, Marshallagia marshalli, with fitness indicators.

• Published in: PLOS ONE
• Main Authors: O Alejadro Aleuy, Kathreen Ruckstuhl, Eric P Hoberg, Alasdair Veitch, Norman Simmons, Susan J Kutz
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science (PLoS) 2018
• Subjects: Medicine; R; Science; Q; Arctic; Canada; Northwest Territories; Mackenzie mountains; Subarctic
• Online Access: https://doi.org/10.1371/journal.pone.0192825; https://doaj.org/article/b3c2fecb76f34449b848535412a51c08

Gastrointestinal helminths can have a detrimental effect on the fitness of wild ungulates. Arctic and Subarctic ecosystems are ideal for the study of host-parasite interactions due to the comparatively simple ecological interactions and limited confounding factors. We used a unique dataset assembled in the early seventies to study the diversity of gastrointestinal helminths and their effect on fitness indicators of Dall's sheep, Ovis dalli dalli, in the Mackenzie Mountains, Northwest Territories, Canada. Parasite diversity included nine species, among which the abomasal nematode Marshallagia marshalli occurred with the highest prevalence and infection intensity. The intensity of M. marshalli increased with age and was negatively associated with body condition and pregnancy status in Dall's sheep across all the analyses performed. The intensity of the intestinal whipworm, Trichuris schumakovitschi, decreased with age. No other parasites were significantly associated with age, body condition, or pregnancy. Our study suggests that M. marshalli might negatively influence fitness of adult female Dall's sheep.