Fascioloides magna in Moose ( Alces alces) From Elk Island National Park, Alberta.

Thirty-seven adult female moose ( Alces alces) from 2 distinct but adjacent populations in Elk Island National Park (EINP), Alberta, Canada (19 in north EINP and 18 in south EINP), were fitted with mortality-sensing VHF radio-collars, and radio signals were acquired daily to ascertain mortality status. At capture, serum, whole blood, and feces were collected; pregnancy was determined; teeth were aged by visual inspection; and a portion of liver was assessed by ultrasound examination. Postmortem examination was conducted on 20 suitable carcasses. Clinical pathological abnormalities, including eosinophilia, polycythemia, elevated levels of liver enzymes in serum, hemoglobin, hematocrit, and red blood cell distribution, and liver damage as seen in ultrasound images occurred only in moose from north EINP. Infected moose had 4.7 ± 4.8 Fascioloides magna flukes per liver (mean ± SD). The proportion of moose pregnant at capture was similar in both populations (74% in north EINP, 61% in south EINP). Proportional mortality was significantly higher in moose from the north (68%) than the south (32%). Fascioloides magna was associated as a cause of death in 7 of 14 (50%) moose in the north where cause of death was determined, while predation ( n = 1), acute toxemic syndrome ( n = 3), dystocia ( n = 1), and roadkill and undetermined causes ( n = 3) were additional causes of mortality. F. magna was associated with poor body condition and was a major cause of mortality in north EINP but not south EINP, despite very similar habitat and proximity, suggesting a significant role for these flukes in affecting health and viability of naturally infected moose populations.

Characterization of neurotropic HPAI H5N1 viruses with novel genome constellations and mammalian adaptive mutations in free-living mesocarnivores in Canada.

The GsGd lineage (A/goose/Guangdong/1/1996) H5N1 virus was introduced to Canada in 2021/2022 through the Atlantic and East Asia-Australasia/Pacific flyways by migratory birds. This was followed by unprecedented outbreaks affecting domestic and wild birds, with spillover into other animals. Here, we report sporadic cases of H5N1 in 40 free-living mesocarnivore species such as red foxes, striped skunks, and mink in Canada. The clinical presentations of the disease in mesocarnivores were consistent with central nervous system infection. This was supported by the presence of microscopic lesions and the presence of abundant IAV antigen by immunohistochemistry. Some red foxes that survived clinical infection developed anti-H5N1 antibodies. Phylogenetically, the H5N1 viruses from the mesocarnivore species belonged to clade 2.3.4.4b and had four different genome constellation patterns. The first group of viruses had wholly Eurasian (EA) genome segments. The other three groups were reassortant viruses containing genome segments derived from both North American (NAm) and EA influenza A viruses. Almost 17 percent of the H5N1 viruses had mammalian adaptive mutations (E627 K, E627V and D701N) in the polymerase basic protein 2 (PB2) subunit of the RNA polymerase complex. Other mutations that may favour adaptation to mammalian hosts were also present in other internal gene segments. The detection of these critical mutations in a large number of mammals within short duration after virus introduction inevitably highlights the need for continually monitoring and assessing mammalian-origin H5N1 clade 2.3.4.4b viruses for adaptive mutations, which potentially can facilitate virus replication, horizontal transmission and posing pandemic risks for humans.

THE RELATIONSHIP BETWEEN HARVEST MANAGEMENT AND CHRONIC WASTING DISEASE PREVALENCE TRENDS IN WESTERN MULE DEER (ODOCOILEUS HEMIONUS) HERDS.

We analyzed retrospective data on harvest management practices and corresponding chronic wasting disease (CWD) prevalence trends in 36 western US and Canadian mule deer (Odocoileus hemionus) management units (units). Our analyses employed logistic regression and model selection, exploiting variation in practices within and among jurisdictions to examine relationships between harvest management and apparent prevalence (the proportion of positive animals among those sampled). Despite notable differences in hunting practices among jurisdictions, our meta-analysis of combined data revealed strong evidence that the amount of harvest was related to CWD prevalence trends among adult male mule deer in the 32 units where prevalence at the start of the analysis period was ≤5%. All competitive models included the number of male deer harvested or number of hunters 1-2 yr prior as an explanatory variable, with increasing harvest leading to lower prevalence among males harvested in the following year. Competitive models also included harvest timing. Although less definitive than the number harvested, median harvest dates falling closer to breeding seasons were associated with lower prevalence in the following year. Our findings suggest harvest-when sufficient and sustained-can be an effective tool for attenuating CWD prevalence in adult male mule deer across western ranges, especially early in the course of an epidemic. Evidence of a broad relationship between the amount of harvest and subsequent changes in CWD prevalence among adult male mule deer provides an empirical basis for undertaking adaptive disease management experimentation aimed at suppressing or curtailing CWD epidemics.

Deep mitochondrial DNA lineage divergences within Alberta populations of Dermacentor albipictus (Acari: Ixodidae) do not indicate distinct species.

The winter tick Dermacentor albipictus (Packard) has a single-host life cycle that allows it to reach severe infestation levels on ungulates, particularly moose. Genotypic variation within these and related ticks has been a source of taxonomic confusion, although the continuity in their morphology and life history has generally been interpreted as indicating the existence of a single species. To further investigate this variation, we sequenced regions of two mitochondrial DNA (mtDNA) genes (COI and 16S rDNA),two nuclear genes (lysozyme and ITS-2), and two bacterial markers from Francisella-like endosymbionts found in these ticks (eubacterial mtDNA 16S rRNA and a homolog of Francisella tularensis [Dorofe'ev] 17-kDa lipoprotein). We sampled 42 D. albipictus individuals from whitetail and mule deer culled from three populations in east-central Alberta, as well as four D. albipictus and two Dermacentor variabilis (Say) from other locations. We then compared DNA sequence variation between the genes and related this to variation in the morphology of spiracle plates. Both mtDNA regions indicated two deeply diverged lineages (mean difference of 7.1% for COI and 4.5% for 16S) that would normally be considered diagnostic of distinct species in DNA barcoding studies. However, very little divergence was revealed by nuclear gene sequences, bacterial endosymbionts, and morphometric analyses, and any variation that did occur in these markers was not congruent with mtDNA divergences. We conclude that the sampled populations in Alberta represent a single species, D. albipictus, and reiterate the importance of integrative approaches in species delimitation.

Polymorphisms at the PRNP gene influence susceptibility to chronic wasting disease in two species of deer (Odocoileus Spp.) in western Canada.

Chronic wasting disease (CWD) is increasingly prevalent in multiple wild mule (Odocoileus hemionus) and white-tailed deer (O. virginianus) herds in North America. CWD was first found in Canadian wild mule deer in Saskatchewan in 2000 and has since spread into the neighboring province of Alberta. The infectious agent for CWD is a misfolded prion protein encoded by the PRNP gene. Previous studies revealed association between PRNP genotype and susceptibility to CWD in both mule and white-tailed deer in other regions. To investigate this link in Canadian populations, PRNP gene sequence was examined in 166 CWD- and 83 CWD+ mule deer, and 197 CWD- and 30 CWD+ white-tailed deer from Saskatchewan and Alberta. Two variable sites were found in mule deer, and 15 in white-tailed deer. In both species PRNP genotype was associated with CWD status. Mule deer possessing at least one copy of the common allele at codon 20 were less likely to test positive for CWD than expected, given the frequency of this allele in the population. A variant at codon 96 in white-tailed deer was also linked with reduced incidence of CWD. A greater knowledge of the genetic sources of heterogeneity in CWD susceptibility may improve our understanding of the mechanisms underlying the CWD epidemic in western Canada.

An expanding population of the giant liver fluke (Fascioloides magna) in elk (Cervus canadensis) and other ungulates in Canada.

Giant liver fluke (Fascioloides magna) populations readily expand under suitable conditions. Although extirpated from the eastern slopes of the Canadian Rocky Mountains in the early 1960s, the fluke reappeared following natural spread through mountain passes from British Columbia. Herein, we assessed epizootiology of the fluke population two decades later. Between 1984 and 1991, 534 ungulates, including 381 elk (Cervus canadensis), 68 mule deer (Odocoileus hemionus hemionus), 54 white-tailed deer (Odocoileus virginianus), and 31 moose (Alces alces) from adjacent areas of Alberta (AB) and British Columbia (BC), Canada, were examined for giant liver flukes. Prevalence in elk increased from 53% to 79% (1984-91) in Banff National Park (BNP) in AB and 77% to 100% (1985-89) in Kootenay National Park (KNP) in BC. Super-infections (>100 flukes) were more common in later years. Generally, prevalence increased over time and with increasing age of elk. Intensity was lowest in young-of-year (BNP 8±5, KNP 3), but similar in yearlings (BNP 36±11, KNP 23±8) and adults (BNP 33±5, KNP 32±6). Prevalence was similar in male and female elk. Intensity was higher in males (BNP 47±7, KNP 46±12) than in females (BNP 28±6, KNP 22±4), although the maximum number of flukes (545) occurred in a female elk. Prevalence and intensity differed among other species of ungulates but patterns were similar in each park. Prevalence was lower in mule deer (BNP 6%, KNP 4%) than in white-tailed deer (BNP 44%, KNP 28%) and moose (BNP 52%, KNP 63%). Intensity differed among these species but never exceeded 30 flukes. Gravid flukes occurred only in elk and white-tailed deer. Transmission occurred primarily in late summer-fall and in wet habitats. At least seven elk died as a direct result of fluke infection. In this region, elk and white-tailed deer maintain the F. magna population with spillover into moose and, rarely, mule deer.

Epizootic hemorrhagic disease in Alberta, Canada.

Epizootic hemorrhagic disease (EHD) virus serotype 2 was identified by reverse-transcription (RT)-PCR in a white-tailed deer (Odocoileus virginianus) found dead in southern Alberta in September 2013. Field observations indicate at least 50 deer, primarily white-tailed deer, and three pronghorn antelope (Antilocapra americana) died during a suspected localized EHD outbreak.

Origin of Dermacentor albipictus (Acari: Ixodidae) on elk in the Yukon, Canada.

Winter ticks (Dermacentor albipictus) on elk (Cervus elaphus canadensis) have recently increased in numbers in the Yukon, Canada, potentially posing risks to other indigenous host species in the region. To evaluate the regional source of winter ticks in the Yukon, we sequenced one nuclear (ITS-2) and two mitochondrial (16SrRNA and COI) genes, and genotyped 14 microsatellite loci from 483 winter tick specimens collected across North America. We analyzed genetic variation across the geographic and host ranges of this tick species with the use of variance partitioning, Bayesian clustering, and standard population genetic analyses. Based on our results, winter ticks on elk in the Yukon could have originated either by translocation from central Alberta or by northward range expansion of more geographically proximate populations in northern Alberta and British Columbia. Although there was some genetic structuring of winter ticks on different hosts in the same region, we found little evidence of host specificity in winter ticks from five ungulate host species, suggesting that the winter ticks on elk in the Yukon could potentially become established on other locally available host species such as moose (Alces alces).

Targeting the detection of chronic wasting disease using the hunter harvest during early phases of an outbreak in Saskatchewan, Canada.

Chronic wasting disease (CWD) is a fatal disease of North American cervids that was first detected in a wild, hunter-shot deer in Saskatchewan along the border with Alberta in Canada in 2000. Spatially explicit models for assessing factors affecting disease detection are needed to guide surveillance and control programs. Spatio-temporal patterns in CWD prevalence can be complicated by variation in individual infection probability and sampling biases. We assessed hunter harvest data of mule deer (Odocoileus hemionus) and white-tailed deer (Odocoileus virginianus) during the early phases of an outbreak in Saskatchewan (i.e., 2002-2007) for targeting the detection of CWD by defining (1) where to look, and (2) how much effort to use. First, we accounted for known demographic heterogeneities in infection to model the probability, P(E), that a harvested deer was infected with CWD given characteristics of the harvest location. Second, in areas where infected deer were harvested we modelled the probability, P(D), of the hunter harvest re-detecting CWD within sample units of varying size (9-54 km(2)) given the demographics of harvested deer and time since first detection in the study area. Heterogeneities in host infection were consistent with those reported elsewhere: mule deer 3.7 times >white-tailed deer, males 1.8 times>females, and quadratically related to age in both sexes. P(E) increased with number of years since the first detection in our study area (2002) and proximity to known disease sources, and also varied with distance to the South Saskatchewan River and small creek drainages, terrain ruggedness, and extent of agriculture lands within a 3 km radius of the harvest. The majority (75%) of new CWD-positive deer from our sample were found within 20 km of infected deer harvested in the previous year, while approximately 10% were greater than 40 km. P(D) modelled at 18 km(2) was best supported, but for all scales, P(D) depended on the number of harvested deer and time since the first infected deer was harvested. Within an 18 km(2) sampling unit, there was an 80% probability of detecting a CWD-positive deer with 16 harvested deer five years after the initial infected harvest. Identifying where and how much to sample to detect CWD can improve targeted surveillance programs early in the outbreak of the disease when based on hunter harvest.

Broad and fine-scale genetic analysis of white-tailed deer populations: estimating the relative risk of chronic wasting disease spread.

Chronic wasting disease is a transmissible spongiform encephalopathy of cervids, similar to sheep scrapie that has only recently been detected in wild populations of white-tailed deer (Odocoileus virginianus) and mule deer (Odocoileus hemionus hemionus) in western Canada. Relatively little is known about local transmission dynamics of the disease or the potential for long-distance spread. We analysed the population genetic structure of over 2000 white-tailed deer sampled from Alberta, British Columbia, and Saskatchewan using microsatellite profiles and mtDNA sequencing to assess the relative risk of disease spread. There was very little differentiation among subpopulations and a weak trend of increasing differentiation with geographic distance. This suggests that the potential for long-distance disease spread through the dispersal of infected individuals is possible, yet the risk of spread should gradually diminish with distance from infection foci. Within subpopulations, females were more related than expected by chance (R > 0) within a radius of approximately 500 m. Sex-biased philopatry and social interactions among related females may facilitate local disease transmission within social groups. Local herd reduction may therefore be an effective tool for reducing the disease prevalence when implemented at the appropriate spatial scale.