Serologic survey for viral and bacterial infections in western populations of Canada lynx (Lynx canadensis)

A serologic survey for exposure to pathogens in Canada lynx (Lynx canadensis) in western North America was conducted. Samples from 215 lynx from six study areas were tested for antibodies to feline parvovirus (FPV), feline coronavirus, canine distemper virus, feline calicivirus, feline herpesvirus, Yersinia pestis, and Francisella tularensis. A subset of samples was tested for feline immunodeficiency virus; all were negative. For all other pathogens, evidence for exposure was found in at least one location. Serologic evidence for FPV was found in all six areas but was more common in southern populations. Also, more males than females showed evidence of exposure to FPV. Overall, prevalences were low and did not exceed 8% for any of the pathogens tested. This suggests that free-ranging lynx rarely encounter common feline pathogens.     

Modoc-like virus isolated from wild deer mice (Peromyscus maniculatus) in Alberta

Small mammals were trapped in northeastern Alberta, Canada during 1976. Blood samples from these animals were tested for virus by inoculation of suckling mice. Blood clots from two deer mice yielded isolates of the same virus. The virus was related antigenically to a number of flaviviruses which have been isolated from mammals in Central America and North America and was related most closely to Modoc virus. Physical, chemical, and biological properties of the virus were similar also to those of Modoc virus. It did not produce illness or death in deer mice inoculated in the laboratory. Neutralization tests indicated that 1/38 (3%) red squirrels (Tamiasciurus hudsonicus), 3/35 (9%) least chipmunks (Eutamius minimus), 13/109 (12%) deer mice, and 3/50 (6%) humans were infected naturally. This is the first reported evidence of infection of red squirrels and chipmunks with a Modoc-like virus. These data extend the range of Modoc-like viruses northward by 1,500 km and comprise the first isolate from mammals in the boreal forest of Canada.     

Serologic survey for infectious canine hepatitis virus in grizzly bears (Ursus arctos) from Alaska, 1973 to 1987

Serum antibody prevalence of infectious canine hepatitis virus was 12% (90 of 725) for grizzly bears (Ursus arctos) from Alaska (USA) during the period 1973 to 1987. Prevalence was highest on Kodiak Island at 29% (37 of 127). Prevalence of exposure at individual collection areas did not change significantly over time. There were no significant sex-specific differences in prevalence. Prevalence was directly related to age, but it was 0% for bears less than 2-yr-old. Young bears which are exposed to the virus may develop clinical disease and die as a result of the infection. This disease may be a factor affecting grizzly bear population dynamics.     

Trichinella sp. in wolves from interior Alaska

Tongue samples were collected from 148 wolf (Canis lupus) carcasses during 1993 and 1994 near Fairbanks (Alaska, USA). A standard peptic digestion procedure was used to detect Trichinella sp. larvae. Larvae were found in 54 of 148 (36%) samples. There was no significant difference in sex-specific prevalence. Prevalence was significantly related to age. There was no relationship between the number of larvae/g of host tissue and the age or sex of the host. Trichinella spp. infection may cause illness in individual wolves. However, there was no indication the parasite had any impact on the population.     

Molecular identification of natural hybrids between Trichinella nativa and Trichinella T6 provides evidence of gene flow and ongoing genetic divergence

To date, there are no data available on the population genetics of Trichinella due to the lack of genetic markers and the difficulty of working with such small parasites. In the Arctic region of North America and along the Rocky Mountains, there exist two genotypes of Trichinella, Trichinella nativa and Trichinella T6, respectively, which are well differentiated by biochemical and molecular characters. However, both are resistant to freezing, show other common biological characters (e.g. low or no infectivity to rodents and swine) and produce fertile F1 offspring upon interbreeding. To data, these two genotypes have been considered allopatric. In this study, we detected both genotypes in wolves of the same wolf packs in Alaska, suggesting sympatry. A single GTT trinucleotide present in the ITS-2 sequence of T. nativa but not in Trichinella T6 was used as a genetic marker to study gene flow for this character in both a murine infection model and in larvae from naturally-infected Alaskan wolves. Only F1 larvae originating from a cross between T. nativa male and Trichinella T6 female were able to produce F2 offspring. Larvae (F1) originating from a cross between Trichinella T6 male and T. nativa female were not reproductively viable. As expected, all F1 larvae showed a heterozygote pattern for the GTT character upon heteroduplex analysis; however, within the F2 population, the number of observed heterozygotes (n=52) was substantially higher than expected (n=39.08), as supported by the F(is) index, and was not in the Hardy-Weinberg equilibrium. Larvae from two of the 16 Trichinella positive Alaskan wolves, showed the Trichinella T6 pattern or the T. nativa/Trichinella T6 hybrid pattern. Our data demonstrate that T. nativa and Trichinella T6 live in sympatry at least in Alaskan wolves, where T. nativa occurs more frequently (69%) than Trichinella T6 (31%). One explanation for this phenomenon is that glacial periods may have caused a geographical relocation, colonisation and independent evolution of T. nativa within the Rocky Mountains, resulting in a bifurcation of the freeze-resistant genotype. Additional studies will be required to test this hypothesis.     

Serologic survey for Toxoplasma gondii in selected wildlife species from Alaska

Blood was collected from selected wildlife species in specific areas of Alaska (USA) during 1976-96. A modified agglutination test was used to test sera for evidence of exposure to Toxoplasma gondii. Serum antibody prevalence was 43% (62 positive of 143 tested) for black bears (Ursus americanus), 9% (11/125) for wolves (Canis lupus), 7% (22/319) for Dall sheep (Ovis dalli), 6% (14/241) for caribou (Rangifer tarandus), 1% (3/240) for moose (Alces alces), and 1% (2/241) for bison (Bison bison). A predictive model was developed to determine the effect of sex, age, location, and year of collection on antibody prevalence for each species. Prevalence was higher in older black bears, caribou, and wolves. For black bears, prevalence was highest in the southeast region of the state. For caribou, prevalence was lowest on the Alaska Peninsula.     

Serologic survey for Toxoplasma gondii in lynx from interior Alaska

Two hundred fifty-five lynx (Felis lynx) carcasses were collected from trappers in Interior Alaska (USA). Serosanguinous fluids were collected from the chest cavity of each carcass. These fluids were tested for evidence of exposure to Toxoplasma gondii by means of a modified agglutination test using formalin fixed tachyzoites and mercaptoethanol. Thirty-nine of the samples had titers greater than or equal to the threshold (> or = 25). Antibody prevalence differed between areas, and was directly related to age of the host.     

Serologic survey for selected microbial pathogens in Alaskan wildlife

Antibodies to Brucella spp. were detected in sera of seven of 67 (10%) caribou (Rangifer tarandus), one of 39 (3%) moose (Alces alces), and six of 122 (5%) grizzly bears (Ursus arctos). Antibodies to Leptospira spp. were found in sera of one of 61 (2%) caribou, one of 37 (3%) moose, six of 122 (5%) grizzly bears, and one of 28 (4%) black bears (Ursus americanus). Antibodies to contagious ecthyma virus were detected in sera of seven of 17 (41%) Dall sheep (Ovis dalli) and five of 53 (10%) caribou. Antibodies to epizootic hemorrhagic disease virus were found in sera of eight of 17 (47%) Dall sheep and two of 39 (6%) moose. Infectious bovine rhinotracheitis virus antibodies were detected in sera of six of 67 (9%) caribou. Bovine viral diarrhea virus antibodies were found in sera of two of 67 (3%) caribou. Parainfluenza 3 virus antibodies were detected in sera of 14 of 21 (67%) bison (Bison bison). Antibodies to Q fever rickettsia were found in sera of 12 of 15 (80%) Dall sheep. No evidence of prior exposure to bluetongue virus was found in Dall sheep, caribou, moose, or bison sera.     

Serologic survey for selected microbial agents in mammals from Alberta, 1976

Blood samples were taken from humans and several species of free-ranging wild mammals from five different geographic areas of Alberta, Canada. Sera were tested for antibody to eastern equine encephalitis (EEE) virus, western equine encephalitis (WEE) virus, St. Louis encephalitis (SLE) virus, Powassan (POW) virus, the snowshoe hare (SSH) strain of the California group (CAL) of viruses, Northway (NOR) virus, Klamath (KLA) virus, infectious bovine rhinotracheitis (IBR) virus, and two bacteria, Brucella abortus and Francisella tularensis. CAL antibody was found in 63% of 11 snowshoe hares (Lepus americanus), 33% of 167 black bears (Ursus americanus), and 19% of 55 humans (Homo sapiens). NOR antibody was found in 0.4% of 258 hares, 11% of 9 bighorn sheep (Ovis canadensis), 20% of 44 moose (Alces alces), 4% of 56 bears, 14% of 22 woodland caribou (Rangifer tarandus), and 2% of 50 humans. IBR antibody was detected in 14% of 14 moose. B. abortus antibody was found in 1% of 283 bears. F. tularensis antibody was detected in 2% of 52 humans. These findings represent extension of: (1) the natural host range of IBR, CAL, and NOR; (2) the geographical distribution of NOR infection in North America; and (3) the geographical distribution of CAL infection within Alberta.