Varestrongylus eleguneniensis, Verocai, Kutz, Simard & Hoberg, 2014

Verocai, Guilherme G., Hoberg, Eric P., Simard, Manon, Beckmen, Kimberlee B., Musiani, Marco, Wasser, Sam, Cuyler, Christine, Manseau, Micheline, Chaudhry, Umer N., Kashivakura, Cyntia K., Gilleard, John S. & Kutz, Susan J., 2020, The biogeography of the caribou lungworm, Varestrongylus eleguneniensis (Nematoda: Protostrongylidae) across northern North America, International Journal for Parasitology: Parasites and Wildlife 11, pp. 93-102 : 97-98

4.1. General findings on Varestrongylus eleguneniensis in caribou herds

We found V. eleguneniensis across caribou populations of three different subspecies and ecotypes, corroborating observations based on less extensive sampling regimes ( Kutz et al., 2007, 2013; Verocai et al., 2014b). Our findings support the wide geographic range previously demonstrated for V. eleguneniensis by these authors and further expand it to areas of northern and interior Alaska, and across the boreal forests of Canada, including the provinces of British Columbia, Saskatchewan, Ontario, and Quebec, and multiple areas of Alberta. As suggested by Kutz et al. (2007) and Verocai et al. (2014b), multiple studies that reported P. andersoni or P. odocoilei in caribou based on presence of DSL in the feces should be reconsidered. These studies occurred prior to the discovery and recent description of V. eleguneniensis , and presumed that, outside of the island of Newfoundland, any DSL in caribou feces was P. andersoni , or less likely P. odocoilei ( Ball et al., 2001; Gray and Samuel, 1986; Jenkins et al., 2005; Johnson et al., 2010; Kutz et al., 2007; Lankester et al., 1976; Lankester and Fong, 1989, 1998; Lankester and Hauta, 1989). Current data for V. eleguneniensis , using molecular and more refined morphological examination, indicates considerable spatial overlap with P. andersoni ( Ball et al., 2001; Gray and Samuel, 1986; Jenkins et al., 2005; Johnson et al., 2010; Kutz et al., 2007; Lankester et al., 1976; Lankester and Fong, 1989, 1998; Lankester and Hauta, 1989). While we further demonstrate the value of molecular diagnostic tools for identification of protostrongylids, recent studies on detailed morphology of DSL when hosts may be co-infected with two species are equally useful tools, and the choice of methods may be related to logistical and financial aspects of a study or health survey ( Kafle et al., 2015, 2017a).

Our findings of V. eleguneniensis across a vast distribution, encompassing different caribou subspecies and ecotypes, support a continuous distribution across partially overlapping mainland populations of caribou in Canada and the US. This includes the large migratory caribou herds in the Arctic and Subarctic, whose winter range may overlap with range of non-migratory herds, and those who undergo short migrations such as the boreal forest and mountain ecotypes. The largely overlapping distribution of the caribou- V. eleguneniensis assemblage may be a product of a concomitant historical geographic colonization by this assemblage after recession of the continental ice, or initial geographic colonization by the host, with subsequent colonization by the parasite, followed by its spread across much of the host's range ( Asmundsson et al., 2008; Hoberg et al., 2008, 2012; Kutz et al., 2007, 2012). Further pieces for this mosaic are the independent events of colonization of new hosts – muskoxen and moose in sympatry with geographically distinct caribou populations (Hoberg, 2010; Hoberg et al., 2012; Kutz et al., 2007; Kutz et al., 2013; Verocai et al., 2014b; present study).