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Migration is typically thought to be an evolved trait driven by responses to forage or predation, but recent studies have demonstrated avoidance of parasitism can also affect success of migratory tactics within a population. We evaluated hypotheses of how migration alters parasite exposure in a partially migratory elk (Cervus canadensis) population in and adjacent to Banff National Park, Alberta, Canada. Equal numbers of elk remain year-round on the winter range or migrate to summer range. We quantified diversity and abundance of parasites in faecal elk pellets, and prevalence (number of infected individuals) and intensity (egg counts) of giant liver fluke eggs (Fascioloides magna) in faeces across migratory tactics. We tested whether giant liver fluke intensity in faeces was affected by elk use of wetlands, elevation, forage biomass, and elk concentration in the previous summer. We rejected the "migratory escape" hypothesis that suggests migration allowed elk to escape parasite exposure because migrant elk had the highest richness and evenness of parasite groups. We also rejected the hypothesis that prevalence was highest at highest summer densities because higher-density resident elk had the lowest diversity and giant liver fluke egg presence and intensity. Instead, the high prevalence and intensity of giant liver flukes in migrants was consistent with both the hypothesis of "environmental tracking", because elk that migrated earlier may expose themselves to favourable parasite conditions, and with the "environmental sampling" hypothesis, because giant liver fluke intensity increased with increased exposure to secondary host habitat (i.e., wetland). Our results indicate that differential exposure of different migratory tactics that leave the winter range has a greater influence on parasites than the concentration of elk that reside on the winter range year-round. Image 1 • Parasites may alter relative fitness in partially migratory populations. • Migration can alter parasite exposure. • Migratory elk had higher parasite diversity, prevalence, and intensity. • Host habitat and timing of migration can increase parasite infection. [ABSTRACT FROM AUTHOR]

Varestrongylus eleguneniensis (Nematoda; Protostrongylidae) is a recently described species of lungworm that infects caribou (Rangifer tarandus), muskoxen (Ovibos moschatus) and moose (Alces americanus) across northern North America. Herein we explore the geographic distribution of V. eleguneniensis through geographically extensive sampling and discuss the biogeography of this multi-host parasite. We analyzed fecal samples of three caribou subspecies (n = 1485), two muskox subspecies (n = 159), and two moose subspecies (n = 264) from across northern North America. Protostrongylid dorsal-spined larvae (DSL) were found in 23.8%, 73.6%, and 4.2% of these ungulates, respectively. A portion of recovered DSL were identified by genetic analyses of the ITS-2 region of the nuclear rDNA or the cytochrome oxidase c subunit I (COI) region of the mtDNA. We found V. eleguneniensis widely distributed among caribou and muskox populations across most of their geographic prange in North America but it was rare in moose. Parelaphostrongylus andersoni was present in caribou and moose and we provide new geographic records for this species. This study provides a substantial expansion of the knowledge defining the current distribution and biogeography of protostrongylid nematodes in northern ungulates. Insights about the host and geographic range of V. eleguneniensis can serve as a geographically extensive baseline for monitoring current distribution and in anticipating future biogeographic scenarios under a regime of accelerating climate and anthropogenic perturbation. Image 1 • Varestrongylus eleguneniensis is a lungworm whose primary host is the caribou. • The muscleworm, Parelaphostrongylus andersoni , co-infects caribou across its range. • We expand the knowledge on distribution of the caribou lungworm and the muscleworm. • Muskoxen sympatric with caribou are infected with the caribou lungworm. • We discuss the biogeography of V. eleguneniensis and Rangifer across North America. [ABSTRACT FROM AUTHOR]

The Atlantic-Gaspésie caribou ( Rangifer tarandus caribou ) population is a small isolated relict herd considered endangered according to the Canadian Species at Risk Act (SARA). This population has low recruitment and survival rates but the potential role of parasites on individual fitness is unknown. In this context, we explored the parasite status of this population with the aim of 1) assessing the occurrence and intensity of parasite infections and the spatial, temporal and individual variations, 2) quantifying parasite richness and investigating factors such as sex and host body condition that may be associated with this variable and 3) evaluating the effects of parasite infections on survival in the Atlantic-Gaspésie caribou population. We examined fecal samples from 32 animals captured in 2013–2014 for eggs, oocysts and larvae of parasites and detected 7 parasite species: dorsal-spined larvae protostrongylids, presumably Parelaphostrongylus andersoni based on PCR identification of a subset, Nematodirus odocoilei and other unidentified Strongyles, Trichuris sp., Capillaria sp., Moniezia sp. and Eimeria sp. For each caribou, mean parasite species richness was 1.8 ± 1.1 (SD). Sex, body condition, year and capture location did not explain parasite prevalence, intensity of infection or richness except for intensity of infection of Capillaria sp. that was positively influenced by body condition. Parasites did not influence survival although mortality was higher for males than for females. We suggest that the relatively low and common gastrointestinal and protostrongylid parasite infections will not be a short-term threat leading to extinction. [ABSTRACT FROM AUTHOR]

Within many species, males are often more heavily parasitised than females. Several hypotheses have been proposed to explain this phenomenon, including immunocompetence handicaps, sexual size dimorphism and behavioural differences. Here we set out to test the latter two hypotheses and make inferences about the former by assessing patterns of ectoparasitism across various life-history stages in a population of North American red squirrels ( Tamiasciurus hudsonicus ). We also conducted an ectoparasite removal experiment to investigate the effects of ectoparasites on male body condition. We found that males were more intensely parasitized than females, but only during the mating period. There was no difference in ectoparasite intensity between male and female juveniles at birth or at emergence, suggesting that ectoparasites do not exploit male red squirrels for longer-range natal dispersal. Male red squirrels in our population were slightly heavier than females, however we did not find any evidence that this dimorphism drives male-biased ectoparasitism. Finally, we could not detect an effect of ectoparasite removal on male body mass. Our results lend support to the hypothesis that ectoparasites exploit their male hosts for transmission and that male red squirrels are important for the transmission dynamics of ectoparasites in this population; however, the mechanisms ( i.e. , immunocompetence, testosterone) are not known. [ABSTRACT FROM AUTHOR]

Umingmakstrongylus pallikuukensis and Varestrongylus eleguneniensis are the two most common protostrongylid nematodes infecting muskoxen in the North American Arctic and Subarctic. First stage larvae (L1) of these lungworms have considerable morphological similarity that makes their differential diagnosis very difficult. Using light microscopy, we studied in detail the L1 of these two species and identified the key differences in morphological and morphometric attributes. Thirty L1 of each species from naturally infected muskox were heat-killed and then assessed for morphological and morphometric features that could be used for species-level differentiation. Key differentiating features include: length and morphology of the tail extension, curvature of the body, ventral post-anal transverse cuticular striations, and total body length. A laboratory guide for differentiation of L1 based on these species-specific characters was prepared and used by an experienced observer to identify an additional 35 L1 extracted from a different set of fecal samples from free-ranging muskoxen with mixed infections. The identities of these L1 were confirmed by sequence analysis of the ITS-2 region of the nuclear ribosomal DNA. Accuracy of morphological identification was 100 percent, reflecting the reliability of the proposed guide for differentiation. Using the guide, three minimally trained lab assistants each fixed and accurately identified 10 of 10 randomly selected L1. Ability to morphologically differentiate these facilitates the monitoring of overlapping range expansion of both parasites in the Canadian Arctic. Studies enabling species-level parasite identification are also critical for defining biodiversity, detecting mixed infections, and understanding host–parasite interactions. Morphological identification is a simple, reliable and cost-effective alternative to labor and equipment intensive molecular methods and can easily be performed in low resource settings. [ABSTRACT FROM AUTHOR]

Global change, including climate, policy, land use and other associated environmental changes, is likely to have a major impact on parasitic disease in wildlife, altering the spatio-temporal patterns of transmission, with wide-ranging implications for wildlife, domestic animals, humans and ecosystem health. Predicting the potential impact of climate change on parasites infecting wildlife will become increasingly important in the management of species of conservation concern and control of disease at the wildlife-livestock and wildlife-human interface, but is confounded by incomplete knowledge of host-parasite interactions, logistical difficulties, small sample sizes and limited opportunities to manipulate the system. By exploiting parallels between livestock and wildlife, existing theoretical frameworks and research on livestock and their gastrointestinal nematodes can be adapted to wildlife systems. Similarities in the gastrointestinal nematodes and the life-histories of wild and domestic ruminants, coupled with a detailed knowledge of the ecology and life-cycle of the parasites, render the ruminant-GIN host-parasite system particularly amenable to a cross-disciplinary approach. [ABSTRACT FROM AUTHOR]

Climate change is occurring very rapidly in the Arctic, and the processes that have taken millions of years to evolve in this very extreme environment are now changing on timescales as short as decades. These changes are dramatic, subtle and non-linear. In this article, we discuss the evolving insights into host-parasite interactions for wild ungulate species, specifically, muskoxen and caribou, in the North American Arctic. These interactions occur in an environment that is characterized by extremes in temperature, high seasonality, and low host species abundance and diversity. We believe that lessons learned in this system can guide wildlife management and conservation throughout the Arctic, and can also be generalized to more broadly understand host-parasite interactions elsewhere. We specifically examine the impacts of climate change on host-parasite interactions and focus on: (I) the direct temperature effects on parasites; (II) the importance of considering the intricacies of host and parasite ecology for anticipating climate change impacts; and (III) the effect of shifting ecological barriers and corridors. Insights gained from studying the history and ecology of host-parasite systems in the Arctic will be central to understanding the role that climate change is playing in these more complex systems. [ABSTRACT FROM AUTHOR]

We assessed the occurrence of endoparasite eggs, cysts, oocysts and larvae in the muskox population of Dovrefjell, Norway, during June and August 2012. This population originates from 13 calves translocated from Eastern Greenland during the 1950s. A total of 167 faecal samples were collected, of which 49% came from identified individuals: 165 were examined by the Baermann and 95 by McMaster techniques and 167 by immunofluorescence antibody test (IFAT). Lungworm larvae recovered in the Baermanns were identified as Protostrongylidae (82%) and Dictyocaulus sp. (76%) based on morphology. Further molecular analyses of the ITS-2 region of two protostrongylid larvae from two muskoxen as Muellerius capillaris. Larval prevalence and intensity differed significantly between samples collected from the different age groups in June and August, with increasing prevalence and intensity in calves during the course of their first summer, whereas intensity decreased in adults from June to August. McMaster test and IFAT were used to determine the occurrence of infections with intestinal strongyles (84%), Moniezia spp. (24%), Nematodirus sp. (2%), Eimeria spp. (98%), Cryptosporidium sp. (14%) and Giardia duodenalis (7%). Molecular analyses of three isolates of Cryptosporidium and Giardia were identified as Cryptosporidium xiaoi and G. duodenalis assemblage A. Although infection intensity of all these intestinal parasites tended to be low, the high level of polyparasitism, together with the other challenges faced by this population living at the edge of their climatic range, means that these infections should not be ignored. The potential that M. capillaris, Cryptosporidium and Giardia infections derive from other sympatric host species (sheep and reindeer) is discussed. [ABSTRACT FROM AUTHOR]

Highlights: [•] We described gastrointestinal nematodes for two caribou populations in Greenland. [•] Abomasa and small intestines from female caribou were examined. [•] Nematodes collected were morphologically identified to species. [•] Abomasal diversity differed between populations and reflected historical processes. [•] Parasite faunas appear structured by species loss and recent host translocations. [Copyright &y& Elsevier]

Highlights: [•] Parelaphostrongylus andersoni causes muscular and lung pathology in Nearctic cervids. [•] We found P. andersoni in an introduced, semi-domesticated reindeer herd in Alaska. [•] Infection of these reindeer may have occurred through indirect contact with native caribou. [•] This nematode may cause subtle deleterious impacts on commercial herding activities. [Copyright &y& Elsevier]