Physiological adaptations to prolonged fasting in the overwintering striped skunk (Mephitis mephitis).

Wintertime physiology of captive striped skunks (Mephitis mephitis) in response to cold ambient temperature (Ta) and fasting was investigated with body temperature (Tb) and activity recordings and analyses of hematology, plasma biochemistry and tissue fatty acids (FA). After 105 days of food deprivation, the skunks were in phase II of fasting indicated by the elevated plasma nonesterified FA and glycerol but no accumulation of nitrogen end products. Shorter-chain saturated and monounsaturated FA together with C18-20 n-3 polyunsaturated FA were preferentially mobilized. Individual amino acids responded to fasting in a complex manner, while essential and nonessential amino acid sums remained stable. Increases in hemoglobin and hematocrit suggested dehydration. The activity levels were lower in mid-January-early March, and the activity bouts were mostly displayed between 17:00-23:00 h. Daily torpor was observed in two females with 29 and 46 bouts. The deepest torpor (Tb<31 °C) occurred between dawn and early afternoon and lasted for 3.3 ± 0.18 h. The average minimum Tb was 29.2 ± 0.15 °C and the lowest recorded Tb was 25.8 °C. There was significant relation between the average 24-h Tb and Ta. Increases in wintertime Ta, as predicted by climate change scenarios, could influence torpor patterns in the species.

Testing for bias in a sentinel species: contaminants in free-ranging domestic, wild, and hybrid mink.

Sentinel species are important tools for studies of biodiversity and environmental health. The American mink (Neovison vison) has long been considered a sentinel of environmental contamination, since the species is known to be sensitive to a number of common contaminants, including polychlorinated biphenyls (PCB) and mercury. Mink may not always satisfy an important criterion of sentinels however--that they are continuous residents of the environment being sampled. This is because domestic mink commonly escape from farms, and can be confused with wild mink in areas where mink ranching is prevalent, biasing estimates of environmental contamination taken from free-ranging mink samples. We tested for bias in a sample of free-ranging mink from Ontario, Canada, where both genetic ancestry (domestic, wild, and domestic-wild hybrid) and contaminant burdens (PCBs and mercury) were known. Of 133 mink sampled for both contaminants and genetic ancestry, 9% were determined to be domestic and 10.5% hybrid animals. We found that including domestic and hybrid mink in our analysis resulted in overestimating mean PCB burdens in wild mink by 27%, and underestimating mercury by 13%. We also investigated morphological methods to aid in excluding domestic mink from free-ranging mink samples and found that we had the highest classification success using skull size (condylobasal length), which was 15% and 12% greater in male and female domestic than wild mink, respectively. Given the potential use of mink as sentinels, and also the potential for bias, we recommend that researchers take steps to exclude domestic mink from free-ranging mink samples in studies of environmental health.

SARS-CoV-2 wildlife surveillance in Ontario and Québec.

Background: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the virus responsible for the coronavirus disease 2019 pandemic, is capable of infecting a variety of wildlife species. Wildlife living in close contact with humans are at an increased risk of SARS-CoV-2 exposure and, if infected, have the potential to become a reservoir for the pathogen, making control and management more difficult. The objective of this study is to conduct SARS-CoV-2 surveillance in urban wildlife from Ontario and Québec, increasing our knowledge of the epidemiology of the virus and our chances of detecting spillover from humans into wildlife. Methods: Using a One Health approach, we leveraged activities of existing research, surveillance and rehabilitation programs among multiple agencies to collect samples from 776 animals from 17 different wildlife species between June 2020 and May 2021. Samples from all animals were tested for the presence of SARS-CoV-2 viral ribonucleic acid, and a subset of samples from 219 animals across three species (raccoons, Procyon lotor; striped skunks, Mephitis mephitis; and mink, Neovison vison) were also tested for the presence of neutralizing antibodies. Results: No evidence of SARS-CoV-2 viral ribonucleic acid or neutralizing antibodies was detected in any of the tested samples. Conclusion: Although we were unable to identify positive SARS-CoV-2 cases in wildlife, continued research and surveillance activities are critical to better understand the rapidly changing landscape of susceptible animal species. Collaboration between academic, public and animal health sectors should include experts from relevant fields to build coordinated surveillance and response capacity.

Aleutian mink disease virus in striped skunks (Mephitis mephitis): evidence for cross-species spillover.

Aleutian mink disease virus (AMDV) causes a parvovirus infection, initially characterized in American mink (Neovison vison), that may have harmful effects on wild populations of susceptible animals. In North America, where American mink are native, the origin, host range, and prevalence of AMDV in wild species is not clear. We studied striped skunks (Mephitis mephitis) and raccoons (Procyon lotor) to determine whether species sympatric with mink are potential reservoirs in the transmission of AMDV to wild mink and mink farms. Antibodies to AMDV were detected in 41% of skunk serum samples (143/347) and AMDV nucleic acids were detected in 32% (14/40) of skunk spleen samples by PCR, indicating that AMDV exposure and infection were frequent in skunks. We detected no AMDV antibodies in 144 raccoon blood samples. Phylogenetic analysis revealed a newly identified AMDV haplogroup consisting of isolates from Ontario skunks and a free-ranging domestic mink from Ontario. Our findings of frequent AMDV infection in skunks, close genetic similarity between skunk and mink AMDV isolates, and evidence of AMDV transmission from skunks to mink support the hypothesis that skunks may be acting as alternative hosts and reservoirs of AMDV to wild mink through cross-species virus spillover.

Testing for Aleutian mink disease virus in the river otter (Lontra canadensis) in sympatry with infected American mink (Neovison vison).

Aleutian mink disease virus (AMDV) occurs in the American mink (Neovison vison) in wild populations and on mink farms and can cause illness and death. The North American river otter (Lontra canadensis) may be exposed to AMDV because of shared space and habitat with mink. Using serology and real-time PCR, we tested river otters across Ontario for AMDV infection. We found no evidence of infection in otters, a surprising finding given the sympatric distribution, niche overlap, and close phylogenetic relationship of the river otter and the American mink. Our results are consistent with the hypothesis that the major point of spillover of AMDV between mink farms and wildlife is manure and composting carcasses on mink farms. Mink farms in Ontario are generally in agricultural landscapes; it is unlikely that river otter use these habitats and thus are likely not exposed to AMDV. We found no evidence that AMD is an important disease for the river otters in Ontario.

Molecular epidemiology of Aleutian disease virus in free-ranging domestic, hybrid, and wild mink.

Aleutian mink disease (AMD) is a prominent infectious disease in mink farms. The AMD virus (AMDV) has been well characterized in Europe where American mink (Neovison vison) are an introduced species; however, in North America, where American mink are native and the disease is thought to have originated, the virus' molecular epidemiology is unknown. As such, we characterized viral isolates from Ontario free-ranging mink of domestic, hybrid, and wild origin at two proteins: NS1, a nonstructural protein, and VP2, a capsid protein. AMDV DNA was detected in 25% of free-ranging mink (45 of 183), indicating prevalent active infection. Median-joining networks showed that Ontario AMDV isolates formed two subgroups in the NS1 region and three in the VP2 region, which were somewhat separate from, but closely related to, AMDVs circulating in domestic mink worldwide. Molecular analyses showed evidence of AMDV crossing from domestic to wild mink. Our results suggest that AMDV isolate grouping is linked to both wild endogenous reservoirs and the long-term global trade in domestic mink, and that AMD spills back and forth between domestic and wild mink. As such, biosecurity on mink farms is warranted to prevent transmission of the disease between mink farms and the wild.

Mink farms predict Aleutian disease exposure in wild American mink.

BACKGROUND: Infectious diseases can often be of conservation importance for wildlife. Spillover, when infectious disease is transmitted from a reservoir population to sympatric wildlife, is a particular threat. American mink (Neovison vison) populations across Canada appear to be declining, but factors thus far explored have not fully explained this population trend. Recent research has shown, however, that domestic mink are escaping from mink farms and hybridizing with wild mink. Domestic mink may also be spreading Aleutian disease (AD), a highly pathogenic parvovirus prevalent in mink farms, to wild mink populations. AD could reduce fitness in wild mink by reducing both the productivity of adult females and survivorship of juveniles and adults. METHODS: To assess the seroprevalence and geographic distribution of AD infection in free-ranging mink in relation to the presence of mink farms, we conducted both a large-scale serological survey, across the province of Ontario, and a smaller-scale survey, at the interface between a mink farm and wild mink. CONCLUSIONS/SIGNIFICANCE: Antibodies to AD were detected in 29% of mink (60 of 208 mink sampled); however, seroprevalence was significantly higher in areas closer to mink farms than in areas farther from farms, at both large and small spatial scales. Our results indicate that mink farms act as sources of AD transmission to the wild. As such, it is likely that wild mink across North America may be experiencing increased exposure to AD, via disease transmission from mink farms, which may be affecting wild mink demographics across their range. In light of declining mink populations, high AD seroprevalence within some mink farms, and the large number of mink farms situated across North America, improved biosecurity measures on farms are warranted to prevent continued disease transmission at the interface between mink farms and wild mink populations.