Effects of Cephenemyia spp. (Diptera: Oestridae) on the nasopharynx of black-tailed deer (Odocoileus hemionus columbianus)

A study was conducted to determine gross and microscopic tissue changes in the nasopharynx of black-tailed deer (Odocoileus hemionus columbianus) infected with nasal bot fly larvae (Cephenemyia spp.). Paired retropharyngeal recesses were the preferred sites for the growing second and third stage larvae of two species of Cephenemyia (C. apicata and C. jellisoni). Retropharyngeal recesses distended into "pouches" that harbored up to 30 larvae. Pouches were oriented caudal-laterally toward the basisphenoid bone of the cranium. Lateral support of the pouch mass was provided by the stylohyoid bone. The laryngeal orifice was never occluded by the enlarged recesses. The distal pouch wall was relatively thin and remained uniform in thickness as expansion progressed. Occasionally, aberrant larvae were found protruding through the distal wall of the pouch. Disruption of the epithelium and submucosa by larval mouth hooks and integumentary spines were examined by scanning electron microscopy. Histological examination of infected recesses revealed substantial loss of epithelium and mucous glands. Enlargement of recesses into pouches resulted from fibrosis. Healing occurred after larvae egressed from the pouches. Degenerating mucous glands, epithelial metaplasia, epithelial desquamation, and intense inflammation were found near larvae. An eosinophilic exudate with a mixture of macrophages and erythrocytes was present in the lumen of the pouch. The presence of larvae within the pouch inhibited secondary bacterial infection and suppuration. Infection by larvae caused severe local trauma and intense tissue response.     

Demodicosis in a mule deer (Odocoileus hemionus hemionus) from Saskatchewan, Canada

Infestation of deer with Demodex spp. mites has been described in white-tailed deer (Odocoileus virginianus) and in Columbian black-tailed deer (Odocoileus hemionus columbianus) in North America, as well as in four species of deer in Europe. We describe Demodex sp. infestation in an adult female mule deer (Odocoileus hemionus hemionus) with skin lesions found dead near Saskatoon, Saskatchewan, Canada. This is believed to be the first report of demodicosis in mule deer.     

Experimental Fascioloides magna infections of mule deer (Odocoileus hemionus hemionus).

Six mule deer (Odocoileus hemionus hemionus) and one white-tailed deer (Odocoileus virginianus), approximately 5-mo-old, each were inoculated orally with 500 metacercariae of Fascioloides magna. All mule deer died from liver fluke infection between 69 and 134 days (mean = 114, SE = 9.9) after inoculation. Between 38 and 326 immature F. magna (mean = 102, SE = 45.5) were recovered from each deer at necropsy. Flukes were present in livers, lungs, and free in pleural and peritoneal spaces. Infection was characterized by necrotizing hepatitis, fibrosing peritonitis and pleuritis, and hematin pigment accumulation in liver, lung, and many other internal organs. Eggs of F. magna first were detected in feces of the white-tailed deer 28 wk after inoculation, and weekly thereafter until the healthy deer was euthanized at 31 wk. At necropsy, 205 F. magna, including 12 encapsulated mature and 193 nonencapsulated immature flukes were recovered from liver, lungs, and free in abdominal and thoracic spaces of the white-tailed deer. Based on these results, F. magna may be fatal to mule deer within 5 mo of infection. Like domestic sheep and goats, mule deer may be highly susceptible to infection, and it is unlikely mule deer can survive infection with large numbers of F. magna.     

Trypanosomes from mule deer, Odocoileus hemionus in Wyoming.

Examination of mule deer, Odocoileus hemionus, from Wyoming in Spring, 1974 (8) and in Winter of 1974-75 (8) revealed trypanosomes in all 16 deer. Spring samples showed dividing epimastigotes as well as normal bloodstream forms. Winter samples showed only normal blood stream forms. These differences are considered to be seasonally related.     

Hybrid swarm between divergent lineages of mule deer (Odocoileus hemionus)

Studies of hybrid zones have revealed an array of evolutionary outcomes, yet the underlying structure is typically characterized as one of three types: a hybrid zone, a hybrid swarm or a hybrid taxon. Our primary objective was to determine which of these three structures best characterizes a zone of hybridization between two divergent lineages of mule deer (Odocoileus hemionus), mule deer and black-tailed deer. These lineages are morphologically, ecologically and genetically distinct, yet hybridize readily along a zone of secondary contact between the east and west slopes of the Cascade Mountains (Washington and Oregon, USA). Using microsatellite and mitochondrial DNA, we found clear evidence for extensive hybridization and introgression between lineages, with varying degrees of admixture across the zone of contact. The pattern of hybridization in this region closely resembles a hybrid swarm; based on data from 10 microsatellite loci, we detected hybrids that extend well beyond the F1 generation, did not detect linkage disequilibrium at the centre of the zone and found that genotypes were associated randomly within the zone of contact. Introgression was characterized as bidirectional and symmetric, which is surprising given that the zone of contact occurs along a sharp ecotone and that lineages are characterized by large differences in body size (a key component of mating success). Regardless of the underlying mechanisms promoting hybrid swarm maintenance, it is clear that the persistence of a hybrid swarm presents unique challenges for management in this region.     

Ocular plague (Yersinia pestis) in mule deer (Odocoileus hemionus) from Wyoming and Oregon

Although plague is relatively rare in wild ungulates, this report describes ocular lesions associated with Yersinia pestis infection in three free-ranging mule deer (Odocoileus hemionus) from Wyoming and Oregon, USA. All deer were observed antemortem and seemed to be blind. Post-mortem examination revealed gross lesions of bilateral keratoconjunctivitis and/or panophthalmitis in the first two deer, but only partial retinal detachment in the third deer. Microscopically, all deer had moderate-to-severe necrotizing and fibrinopurulent endophthalmitis and varying degrees of keratoconjunctivitis with abundant intralesional coccobacilli. The lesions in the first (D1) and third deer (D3) suggested an acute course, whereas those in the second deer (D2) were subacute to chronic. Yersinia pestis was isolated from ocular tissue swabs or ocular fluids of D1 and D2, and it was demonstrated by immunohistochemistry within ocular lesions of D1 and D3. Although plague does not seem to be a major cause of morbidity or mortality in free-ranging mule deer, keratoconjunctivitis or pinkeye is relatively common in these animals and plague should be considered as a differential diagnosis in such cases, with appropriate precautions taken to protect the human and animal health.     

Prevalence of agglutinating antibodies to Toxoplasma gondii in adult and fetal mule deer (Odocoileus hemionus) from Nebraska

Toxoplasma gondii is an apicomplexan parasite of mammals and birds. Herbivores acquire postnatal infection by ingesting oocysts from contaminated food or water. Toxoplasma gondii infection is common in white-tailed deer, Odocoileus virginianus, but little is known about the prevalence of infection in mule deer, O. hemionus. We examined sera from 89 mule deer from Nebraska for agglutinating antibodies to T. gondii using the modified direct agglutination test (MAT) with formalin-fixed tachyzoites as antigen. Thirty-one (35%) of the samples were positive at dilutions of > or = 1:25. Samples were examined from 29 fetuses from these mule deer and none were positive in the MAT. Sera from 14 white-tailed deer from Nebraska were also examined and 6 (43%) were positive for T. gondii. Samples were examined from 5 fetuses from these white-tailed deer and none was positive in the MAT. Our results in both deer species from Nebraska are similar to studies conducted in white-tailed deer from other regions of the United States. Our findings indicate that mule deer are frequently infected with T. gondii and that mule-deer meat may be a source of human infection.     

Techniques for evaluating humoral and cell-mediated immunity in mule deer fawns (Odocoileus hemionus).

Twenty mule deer fawns (Odocoileus hemionus) were removed from their dams 48 h after birth, and hand-reared. Methods for monitoring their immune capability are described. Passive humoral immunity was determined by serum protein electrophoresis. Active humoral immunity following Clostridium toxoid vaccination was determined by immunodiffusion. Cell-mediated immunity was assayed using contact sensitization to 1-nitro, 2,4-dichlorobenzene (DNCB).     

Fertility in an F1 male hybrid of white-tailed deer (Odocoileus virginianus) x mule deer (O. hemionus)

The fecundity of an F1 male hybrid deer, from a cross between a male Odocoileus virginianus (white-tailed deer) and a female O. hemionus (mule deer), was assessed by cytogenetic and flow cytometric techniques. Analysis of chromosome morphology, nucleolus organizer expression, meiotic chromosome pairing, sperm production, and nuclear gene inheritance revealed no genetic anomalies that could potentially impair normal fertility. These observations are discussed in relation to recent reports of hybridization between natural populations of these two species.     

An epizootic of besnoitiosis in captive caribou (Rangifer tarandus caribou), reindeer (Rangifer tarandus tarandus) and mule deer (Odocoileus hemionus hemionus)

Besnoitia sp. was diagnosed in two caribou (Rangifer tarandus caribou) which died of pneumonia at the Assiniboine Park Zoo (Winnipeg, Manitoba, Canada) in 1983. During the following 3 yr besnoitiosis spread to an isolated herd of caribou, to mule deer (Odocoileus hemionus hemionus) and to reindeer (Rangifer tarandus tarandus). Reduction of exposure to biting insects appears to have reduced the transmission of besnoitiosis within the reindeer herd. The morbidity rate was approximately 82% in caribou and 67% in mule deer over the age of 2 mo. Most animals with clinical signs were euthanized; this precluded an estimation of the disease-related mortality rate. Twenty-eight caribou, 10 mule deer and three reindeer have been euthanized or died as a result of this epidemic. Attempts to artificially transmit the disease to potentially susceptible intermediate and definitive hosts were unsuccessful.     

Species-wide phylogeography of North American mule deer (Odocoileus hemionus): cryptic glacial refugia and postglacial recolonization

Quaternary climatic oscillations greatly influenced the present-day population genetic structure of animals and plants. For species with high dispersal and reproductive potential, phylogeographic patterns resulting from historical processes can be cryptic, overshadowed by contemporary processes. Here we report a study of the phylogeography of Odocoileus hemionus , a large, vagile ungulate common throughout western North America. We examined sequence variation of mitochondrial DNA (control region and cytochrome b ) within and among 70 natural populations across the entire range of the species. Among the 1766 individual animals surveyed, we recovered 496 haplotypes. Although fine-scale phylogenetic structure was weakly resolved using phylogenetic methods, network analysis clearly revealed the presence of 12 distinct haplogroups. The spatial distribution of haplogroups showed a strong genetic discontinuity between the two morphological types of O. hemionus , mule deer and black-tailed deer, east and west of the Cascade Mountains in the Pacific Northwest. Within the mule deer lineage, we identified several haplogroups that expanded before or during the Last Glacial Maximum, suggesting that mule deer persisted in multiple refugia south of the ice sheets. Patterns of genetic diversity within the black-tailed deer lineage suggest a single refugium along the Pacific Northwest coast, and refute the hypothesis that black-tailed deer persisted in one or more northern refugia. Our data suggest that black-tailed deer recolonized areas in accordance with the pattern of glacial retreat, with initial recolonization northward along a coastal route and secondary recolonization inland.     

Columbian black-tailed deer (Odocoileus hemionus columbianus) as hosts for Borrelia spp. in northern California

The prevalence of infection of Columbian black-tailed deer (Odocoileus hemionus columbianus) with Borrelia spp. was evaluated in an area of northwestern California (USA) where Lyme disease is endemic and the relapsing-fever group spirochete Borrelia coriaceae is enzootic, and in a far-removed comparison area having a disparate climate and lower density of vector ticks. Blood samples collected from both deer herds in 1987, 1988, and from 2000-02 were assayed for borrelial infection with microscopic and molecular methods. Serum specimens from two (5%) of 39 deer from the Dye Creek Preserve in Tehama County versus 13 (20%) of 64 animals from the Hopland Research and Extension Center (HREC) in Mendocino County, California were polymerase chain reaction (PCR) test positive for B. burgdorferi sensu lato. DNA sequencing analyses revealed that eight animals were infected with B. bissettii, six with three unclassified genotypes, and one with B. burgdorferi sensu stricto. One serum sample (2%) from HREC was positive for a relapsing-fever group spirochete that had a 16S rRNA sequence homology of 99% with the C053 type strain of B. coriaceae. Spirochetes undetermined to geno-species were detected in thick-blood drops prepared from three (8%) of 36 deer from the HREC by direct immunofluorescence. Adults of the hippoboscid flies Lipoptena depressa (n=73) and Neolipoptena ferrisi (n=24), the Pacific Coast tick (Dermacentor occidentalis) (n=22), and the western black-legged tick (Ixodes pacificus) (n=1) that had been removed from deer from both study areas in 2002 were PCR test negative for borreliae. The occurrence of diverse borreliae in deer from northern California confounds and, consequently, reduces the utility of borrelial serosurveys for detecting specific genospecies, unless they are complemented by more specific assays (e.g., immunoblotting, PCR/sequencing analysis).     

Prevalence and ultrastructure of three types of Sarcocystis in mule deer, Odocoileus hemionus (Rafinesque), in Montana

Infection with Sarcocystis (Protozoa: Sarcocystidae) was diagnosed in 130 of 153 (85%) samples of muscle from mule deer around Bozeman, Montana. Three structurally distinct mature and microscopic sarcocysts with characteristic cyst walls were found. Cyst walls of type I sarcocysts were about 2 microns thick and had characteristic inverted tee-shaped villar projections; these cysts were considered to be S. hemionilatrantis Hudkins and Kistner, 1976. Cyst walls in type II sarcocysts were thick-walled (about 7 microns) and their villar projections were 6.7 X 1.1 micron. The core of the villar projections consisted of granular material and some filamentous structures. Bradyzoites were 11.6 X 2.8 microns and were tightly packed in compartments. Cyst walls of type III sarcocysts were also thick-walled (about 9 microns) but the villar projections were 8.5 X 4.7 microns. Bradyzoites were 13 X 3.3 microns and were loosely arranged in compartments.     

Migratory strategies, fawn recruitment, and winter habitat use by urban and rural mule deer (Odocoileus hemionus)

We examined the migratory strategies of mule deer (Odocoileus hemionus) using adjacent urban and rural winter ranges in northern Utah in relation to deer demography and patterns of habitat use. Urban deer were more likely to be migratory than rural deer, even though migratory animals from the two herds intermixed on a common, high-elevation summer range. Urban deer exhibited lower fawn recruitment than rural deer; but within each herd, demographic characteristics of migratory and nonmigratory animals suggested that game theory explained the ratios of deer adopting each behavior. Estimates of animal numbers and available habitat did not reveal clearly whether deer densities differed on the two winter ranges. However, patterns of habitat use by urban deer were so clustered around areas of concealment vegetation that animals probably experienced higher local densities than rural animals. In addition, the clustered patterns of habitat use by urban deer resulted in incomplete use of available forage. This may have contributed to the relatively poor fawn recruitment by urban deer, a phenomenon that appeared to be perpetuated by their strong fidelity to winter range.     

A review of the population dynamics of mule deer and black‐tailed deer Odocoileus hemionus in North America

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