Muskox Lungworm (Umingmakstrongylus Pallikuukensis) Does Not Establish in Experimentally Exposed Thinhorn Sheep (Ovis Dalli)

Abstract

Muskoxen (Ovibos moschatus moschatus) on the northwestern mainland of Nunavut and Northwest Territories, Canada, are infected with the protostrongylid lungworm, Umingmakstrongylus pallikuukensis. The geographic range of this muskox population is expanding to the south and west, and it is anticipated that these animals will eventually become sympatric with Dall's sheep (Ovis dalli dalli) in the Mackenzie and Richardson Mountains. To address the concern of wildlife managers that U. pallikuukensis may infect and adversely affect Dall's sheep, four Dall's/Stone's (Ovis dalli stonei) hybrid lambs and one adult muskox (Ovibos moschatus wardi) were each given 100 third-stage larvae of U. pallikuukensis. All animals were intensively monitored for 9 mo postinfection (PI) using clinical examinations, fecal analyses, hematology, blood chemistry, and medical imaging. No first-stage larvae of U. pallikuukensis were recovered from the lambs, and monitoring revealed no evidence that the parasite had established in any of these animals. First-stage larvae were found in the feces of the muskox beginning at 94 days PI, and typical parasite cysts were visible in lung radiographs at 188 days PI. This study addresses an important management and wildlife health issue associated with the potential for host-switching of pathogens and indicates that it is improbable that thinhorn sheep are suitable hosts for U. pallikuukensis.

Temperature-dependent development and freezing survival of protostrongylid nematodes of Arctic ungulates: implications for transmission

“…Two lung nematodes, Umingmakstrongylus pallikuukensis Hoberg, Polley, Gunn & Nishi, 1995 and Varestrongylus eleguneniensis Verocai, Kutz, Simard & Hoberg, 2014, are parasites of Arctic ungulates in areas of the Canadian Arctic mainland and Victoria Island in the Arctic Archipelago [ 19 – 21 ]. Umingmakstrongylus pallikuukensis is a host specialist and only infects muskoxen ( Ovibos moschatus ) [ 22 , 23 ], whereas V. eleguneniensis is a multi-host parasite that infects muskoxen, caribou ( Rangifer tarandus ) and moose ( Alces alces ) [ 20 , 21 , 24 ]. The life-cycle of both parasites is indirect and involves a gastropod intermediate host.…”

Climate change, parasites and shifting boundaries

“…A similar model for P. odocoilei indicated that temperature constraints affecting larval development rates in gastropods may define the northern limits of the parasite’s distribution, and that warming may remove these and lead to an expanded parasite distribution [10]. Also, for U. pallikuukensis , attempted experimental infections indicated that thinhorn sheep, potentially newly sympatric with muskoxen as a result of shifts in host geographic distributions perhaps associated with climate change, are not susceptible to the parasite [32]. …”

Climate Change/Global Warming and Its Impacts on Parasitology/ Entomology

“…Global climate change is actually altering the ecology of infectious agents and driving the emergence of disease in people, domestic animals, and wildlife [81]. Studies of the impact of climate warming on development rates and availability of an important parasitic nematode (Umingmakstrongylus pallikuukensis) of muskoxen in the Canadian Arctic, which is a region that is particularly vulnerable to climate change showed that warming in the Arctic may have already radically altered the transmission dynamics of this parasite, escalating infection pressure for muskoxen, and that this trend is expected to continue [82].…”

“…Climate change due to anthropogenetic activities alters both physical and biological systems globally [21,82]. This is seen in the shifting patterns of abundance and distribution of pathogens, including metazoan and protozoan parasites, and the emergence of infectious disease in people, livestock and wildlife, are among the most important impacts of climate change [18][19][20][21][22][23].…”

“…Importantly, larval stages in gastropods are buffered from the external environment because of microhabitat selection by these intermediate hosts, and consequently, survival and development rates of larvae are less likely to be impacted by climate variability and stochasticity [91] than parasites with direct life cycles. Conversely, the free-living L1 and emerged L3 may be adversely affected by extreme temperatures, desiccation, ultraviolet radiation, and frequency of freeze-thaw cycles, all possible outcomes of climate change at high latitudes [82,92,93] Climate-driven habitat perturbations are also predicted to influence habitat quantity and quality, nutrition, behaviour, immune function and patterns of geographic distribution and abundance of definitive hosts [16,76,92]. The final outcome for the health and persistence of muskox populations will depend on the interactions among these numerous climate-linked factors.…”