Muscleworms, Parelaphostrongylus andersoni (Nematoda: Protostrongylidae), discovered in Columbia white-tailed deer from Oregon and Washington: Implications for biogeography and host associations.

Authors: Asmundsson, Ingrid; MORTENSON, JACK - VET SERVICES,SALEM OR; Hoberg, Eric

Submitted to: Journal of Wildlife Diseases
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/1/2008
Publication Date: 4/1/2008
Citation: Asmundsson, I.M., Mortenson, J.A., Hoberg, E.P. 2008. Muscleworms, Parelaphostrongylus andersoni (Nematoda: Protostrongylidae), discovered in Columbia white-tailed deer from Oregon and Washington: Implications for biogeography and host associations. Journal of Wildlife Diseases. 44: 16-27.

Interpretive Summary: : Host and geographic distribution for some nematode parasites among ungulates in western North America are poorly understood. Our knowledge has often been limited due to the difficulty in detecting and identifying parasites, particularly those nematodes that live in the musculature of their ruminant hosts. Among these parasites, Parelaphostrongylus andersoni is considered a characteristic nematode infecting white-tailed deer. Fecal samples collected from the northern population of Columbia white-tailed deer (Odocoileus virginianus leucurus) in Oregon and Washington State were examined for dorsal-spined larvae. Molecular sequence data were used to identify and establish a new record for P. andersoni in a subspecies of white-tailed deer previously unrecognized as hosts. Further, the known geographic range for this nematode is extended substantially to the west and into the basin of the lower Columbia River in Oregon and Washington. Collections were taken during the process of translocation of animals within the Columbia River Refuge. Thus the sources for animals and their history are known, and it is clear that P. andersoni has been disseminated with these movements of infected host animals. Although the muscleworm is likely to be distributed throughout this refuge, clearly demonstrated is the role of host re-location as a determinant of parasite introduction and establishment. This serves to demonstrate the pervasive nature of anthropogenic events, and particularly conservation-based or management-based decisions for translocation that may influence the overall distribution of parasites and pathogens and constitutes a strong justification for development of baselines and archival collections for biodiversity to document faunal perturbation. Fecal-based surveys in conjunction with population level genetic analysis will be a powerful tool for timely assessment of (1.) geographic range; (2.) rapidly changing patterns of distribution, such as those anticipated with habitat perturbation and global climate change; and (3.) for elucidating the complex coevolutionary history between these parasites and their hosts.

Technical Abstract: Host and geographic distribution for Parelaphostrongylus andersoni, considered a characteristic nematode infecting white-tailed deer, remain poorly defined particularly in the region of western North America. Fecal samples collected from the northern population of Columbia white-tailed deer (Odocoileus virginianus leucurus).were examined for dorsal-spined larvae. Multi-locus data (ITS-2 and COI) establish a new record for P. andersoni in a subspecies of white-tailed deer previously unrecognized as hosts. Further, the known geographic range for this elaphostrongyline is extended substantially to the west and into the basin of the lower Columbia River in Oregon and Washington. It is not yet determined if populations of P. andersoni known in O.v. ochrourus from southeastern British Coumbia are in contact with those in Columbia white-tailed deer. Current data indicate a potentially broad zone of sympatry for P. andersoni and P. odocoilei in the western region of North America, although these elaphostrongylines appear to be segregated respectively in white tailed deer or in black-tailed and mule deer at temperate latitudes. We confirm a geographically extensive range for P. andersoni in white-tailed deer. A putative sister-species association with P. odocoilei, suggests that the distribution of this elaphostrongyline is limited to the Nearctic and occurrence P. andersoni in caribou (subspecies of Rangifer tarandus) is attributable to one or more events of host switching during the Pleistocene.