Submitted to: Journal of Wildlife Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/21/2000
Publication Date: N/A
Citation: Interpretive Summary: Nematodes in the family Protostrongylidae are serious pathogens in wild sheep from North America. Although these parasites are recognized threats to animal health, particularly at the interface of domestic and wild ecosystems, we continue to have limited knowledge about the host and geographic distribution for these parasites. Biodiversity survey for parasites in Dall's sheep in the Mackenzie Mountains, Northwest Territories, Canada revealed infections of lungworms, Protostrongylys stilesi, and muscleworms, Parelaphostrongylus odocoilei. These represent new host and geographic records and the first confirmed identification of these parasites in wild thinhorn sheep. The presence of these species in single hosts was also unique, and the possible synergistic effects of combined infections for individual hosts and for host populations could be significant with respect to the distribution of disease attributable to parasites. These new data are significant in substantially changing our understanding of patterns for host and geographic distribution for these pathogenic parasites in North America, and add to our basic knowledge for biodiversity of helminth parasites in ruminants.
Technical Abstract: First-stage larvae (L1) of at least two species of Protostrongylidae were found in feces from Dall's sheep (Ovis dalli dalli) collected from July to October, 1997, at four sites (ca. 63-65 degrees N; 128-130 degrees W) in the northern Mackenzie Mountains, Northwest Territories (NT), Canada. Spike- tailed L1 (prevalence 74 percent, 0.2-700 larvae per gram (LPG)), were indistinguishable from Protostrongylus sp., and dorsal- spined L1 (prevalence 77 percent,0.2-967 LPG) were structurally and morphometrically most similar to Parelaphostrongylus odocoilei. Experimental infections of the slugs Deroceras laeve and D. reticulatum with the dorsal-spined L1 yielded third-stage larvae (L3) by 28 and 48 days post-infection, respectively. Subsequently, adults of P. odocoilei were recovered from the skeletal musculature of six naturally infected Dall's sheep ewes collected in October 1998 and April 1999 from the Mackenzie Mountains, NT. In the muscles, adult nematodes were associated with grossly visible hemorrhages and localized myositis. In the lungs, eggs and larvae were associated with diffuse granulomatous inflammation. Adult Protostrongylus stilesi were recovered from the lungs of four hunter-killed sheep in 1997 and 1998. The findings of P. stilesi and P. odocoilei in Dall's sheep from the Mackenzie Mountains, NT, represent new host and geographic records. The high prevalence and intensity of infections suggest that these parasites have been historically established in these Dall's sheep.