Wildlife Investigations Laboratory

Rancho Cordova, CA, United States

Wildlife Investigations Laboratory

Rancho Cordova, CA, United States
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Clifford D.L.,University of California at Davis | Clifford D.L.,Wildlife Investigations Laboratory | Kazwala R.R.,Sokoine University of Agriculture | Sadiki H.,Sokoine University of Agriculture | And 4 more authors.
Epidemiology and Infection | Year: 2013

Mycobacterium bovis, a pathogen of conservation, livestock, and public health concern, was detected in eight species of wildlife inhabiting protected areas bordering endemic livestock grazing lands. We tested tissues from 179 opportunistically sampled hunter-killed, depredation, road-killed, and live-captured wild animals, representing 30 species, in and adjacent to Ruaha National Park in south-central Tanzania. Tissue culture and PCR were used to detect 12 (8·1%) M. bovis-infected animals and 15 (10·1%) animals infected with non-tuberculosis complex mycobacteria. Kirk's dik-dik, vervet monkey, and yellow baboon were confirmed infected for the first time. The M. bovis spoligotype isolated from infected wildlife was identical to local livestock, providing evidence for livestock-wildlife pathogen transmission. Thus we advocate an ecosystem-based approach for bovine tuberculosis management that improves critical ecological functions in protected areas and grazing lands, reduces focal population density build-up along the edges of protected areas, and minimizes ecological stressors that increase animals' susceptibility to bovine tuberculosis. Copyright © Cambridge University Press 2013.

Girard Y.A.,University of California at Davis | Rogers K.H.,Wildlife Investigations Laboratory | Woods L.W.,University of California at Davis | Chouicha N.,University of California at Davis | And 2 more authors.
Infection, Genetics and Evolution | Year: 2014

The Pacific Coast band-tailed pigeon (Patagioenas fasciata monilis) is a migratory game bird of North America that is at risk for population decline. Epidemics of avian trichomonosis caused by upper digestive tract infection with Trichomonas spp. protozoa in these and other doves and pigeons of the United States are sporadic, but can involve tens of thousands of birds in a single event. Herein, we analyze the role of trichomonosis in band-tailed pigeon mortality and relate spatial, temporal and demographic patterns of parasite transmission to the genetic background of the infecting organism. Infections were most common in adult birds and prevalence was high in band-tailed pigeons sampled at mortality events (96%) and rehabilitation centers (36%) compared to those that were hunter-killed (11%) or live-caught (4%). During non-epidemic periods, animals were primarily infected with T. gallinae Fe-hydrogenase subtype A2, and were less often infected with either T. gallinae subtype A1 (the British finch epidemic strain), T. stableri n. sp. (a T. vaginalis-like species), or Tritrichomonas blagburni n. sp.-like organisms. Birds sampled during multiple epidemics in California were only infected with T. gallinae subtype A2 and T. stableri. The non-clonal etiology of avian trichomonosis outbreaks in band-tailed pigeons and the risk of spill-over to raptor and passerine species highlights the need for additional studies that clarify the host range and evolutionary relationships between strains of Trichomonas spp. in regions of trichomonosis endemicity. © 2014 Elsevier B.V.

Stephenson N.,University of California at Davis | Swift P.,Wildlife Investigations Laboratory | Moeller R.B.,California Animal Health and Food Safety Laboratory System | Worth S.J.,University of California at Davis | Foley J.,University of California at Davis
Journal of Wildlife Diseases | Year: 2013

Feline infectious peritonitis (FIP) is a fatal immune-mediated vasculitis of felids caused by a mutant form of a common feline enteric virus, feline enteric coronavirus. The virus can attack many organ systems and causes a broad range of signs, commonly including weight loss and fever. Regardless of presenta-tion, FIP is ultimately fatal and often presents a diagnostic challenge. In May 2010, a malnour-ished young adult male mountain lion (Puma concolor) from Kern County, California, USA was euthanized because of concern for public safety, and a postmortem examination was performed. Gross necropsy and histopathologic examination revealed necrotizing, multifocal myocarditis; necrotizing, neutrophilic, and his-tiocytic myositis and vasculitis of the tunica muscularis layer of the small and large intes-tines; and embolic, multifocal, interstitial pneu-monia. Feline coronavirus antigen was detect-ed in both the heart and intestinal tissue by immunohistochemistry. A PCR for coronavirus performed on kidney tissue was positive, con-firming a diagnosis of FIP. Although coronavirus infection has been documented in mountain lions by serology, this is the first confirmed report of FIP. © Wildlife Disease Association 2013.

Silbernagel C.,University of California at Davis | Silbernagel C.,Hubbs SeaWorld Research Institute | Clifford D.L.,Wildlife Investigations Laboratory | Clifford D.L.,University of California at Davis | And 3 more authors.
Diseases of Aquatic Organisms | Year: 2013

Pathogen introduction by invasive species has been speculated to be a cause of declining western pond turtle Emys marmorata populations in California, USA. This study determined the prevalence of Ranavirus spp., Herpesvirus spp., Mycoplasma spp. (via polymerase chain reaction of blood and nasal flush contents), and Salmonella spp. infection (via fecal culture) in native E. marmorata and invasive red-eared sliders Trachemys scripta elegans and compared infection prevalence in E. marmorata populations sympatric with T. scripta elegans to E. marmorata populations that were not sympatric by sampling 145 E. marmorata and 33 T. scripta elegans at 10 study sites throughout California. Mycoplasma spp. were detected in both species: prevalence in E. marmorata was 7.8% in the northern, 9.8% in the central, and 23.3% in the southern California regions. In T. scripta elegans, Mycoplasma spp. were not detected in the northern California region but were detected at 4.5 and 14.3% in the central and southern regions, respectively. All turtles tested negative for Herpesvirus spp. and Ranavirus spp. Enteric bacteria but not Salmonella spp. were isolated from feces. E. marmorata populations that were sympatric with T. scripta elegans did not have increased risk of Mycoplasma spp. infection. For E. marmorata, there was a significant association between Mycoplasma spp. infection and lower body weight and being located in the southern California region. This study is the first of its kind to document pathogen prevalence in native E. marmorata habitats and those sympatric with T. scripta elegans in California. © Inter-Research 2013.

Foley J.,University of California at Davis | Branston T.,07 West Line Street | Woods L.,California Animal Health and Food Safety | Clifford D.,Wildlife Investigations Laboratory | Clifford D.,University of California at Davis
Journal of Parasitology | Year: 2013

The entire range of the critically endangered Amargosa vole (Microtus californicus scirpensis) consists of less than 20 km2 of riparian habitat in the Amargosa River drainage of the Mojave Desert in southern California. In September 2010, deformities on ears and chiggers on the ears and genitalia were detected, with some individuals so severely affected that they were missing ear pinnae altogether. Follow-up trapping was performed to document the presence of mites and mite-associated disease, and molecular characterization was performed on the mites. Of 151 Amargosa voles sampled from February to April of 2011, 60 (39.7%) voles had hard orange mites adhered to some part of their bodies, on ears of 46 (76.7%), on genitalia of 11 (18.3%), and near mammary tissue of 13 (21.7%) voles. Gross lesions were not detected on genitalia, but 47% of all individuals examined showed pinnal lesions and deformities, which included alopecia, swelling, marginal necrosis, and ulceration, as well as scarring, scabbing, and loss of pinna mass covering 25-100% of the pinnae. Biopsies revealed parakeratotic hyperkeratosis and acanthosis with diffuse neutrophilic exocytosis and dense necrotic granulocytes in the epidermis and superficial dermis associated with focal erosion and ulceration. In the underlying dermis, there were dense pleocellular inflammatory cell infiltrates composed primarily of necrotic granulocytes and multifocal hemorrhage. In some samples, mite mouthparts could be seen penetrating the superficial epidermis associated with focal necrosis, and mite fragments were found on the surface epidermis and within hair follicles. Microscopic examination of the mites documented that they were a larval trombiculid in the genus Neotrombicula with anatomical features that most closely resemble Neotrombicula microti, based on scutal shape, setation, and texture. PCR of 2 mite pools (each consisting of 3 mites from an individual animal) amplified 331 bp amplicons, which had 92-97% homology with the 18S rRNA gene of Leptotrombidium deliense, although coverage of Trombiculidae in GenBank is sparse. The severity and prevalence of lesions due to this chigger were atypical and distinct. Severe clinical trombiculiasis in this endangered species could negatively impact individual health and fitness. © American Society of Parasitologists 2013.

Foley J.,University of California at Davis | Clifford D.,Wildlife Investigations Laboratory | Clifford D.,University of California at Davis | Castle K.,National Park Service | And 2 more authors.
Conservation Biology | Year: 2011

White-nose syndrome (WNS) is a fatal disease of bats that hibernate. The etiologic agent of WNS is the fungus Geomyces destructans, which infects the skin and wing membranes. Over 1 million bats in six species in eastern North America have died from WNS since 2006, and as a result several species of bats may become endangered or extinct. Information is lacking on the pathogenesis of G. destructans and WNS, WNS transmission and maintenance, individual and site factors that contribute to the probability of an outbreak of WNS, and spatial dynamics of WNS spread in North America. We considered how descriptive and analytical epidemiology could be used to fill these information gaps, including a four-step (modified) outbreak investigation, application of a set of criteria (Hill's) for assessing causation, compartment models of disease dynamics, and spatial modeling. We cataloged and critiqued adaptive-management options that have been either previously proposed for WNS or were helpful in addressing other emerging diseases of wild animals. These include an ongoing program of prospective surveillance of bats and hibernacula for WNS, treatment of individual bats, increasing population resistance to WNS (through vaccines, immunomodulators, or other methods), improving probability of survival from starvation and dehydration associated with WNS, modifying hibernacula environments to eliminate G. destructans, culling individuals or populations, controlling anthropogenic spread of WNS, conserving genetic diversity of bats, and educating the public about bats and bat conservation issues associated with WNS. ©2011 Society for Conservation Biology. No claim to original US government works.

PubMed | California State University, Stanislaus, Wildlife Investigations Laboratory, 5 California Living Museum, University of California at Davis and 4 California Animal Health and Food Safety Laboratory
Type: Journal Article | Journal: Journal of wildlife diseases | Year: 2016

The San Joaquin kit fox ( Vulpes macrotis mutica) is a federally endangered small carnivore whose distribution is limited to the San Joaquin Valley in central California. Population decline is due to profound habitat loss, and conservation of all remaining populations is critical. A robust urban population occurs in the city of Bakersfield. In spring of 2013, putative cases of mange were reported in this population. Mites from affected animals were confirmed to be Sarcoptes scabiei morphologically and by DNA sequencing. By the end of 2014, 15 cases of kit foxes with mange had been confirmed. As with other species, sarcoptic mange in kit foxes is characterized by intense pruritus and dermatitis, caused by mites burrowing into the epidermal layers, as well as alopecia, hyperkeratosis, and encrustations, secondary bacterial infections, and finally extreme morbidity and death. Of the 15 cases, six foxes were found dead, six were captured but died during attempted rehabilitation, and three were successfully treated. We have no evidence that untreated kit foxes can recover from mange. Sarcoptic mange constitutes a significant threat to the Bakersfield kit fox population and could pose an even greater threat to this imperiled species if it spreads to populations in nearby natural lands.

PubMed | Wildlife Investigations Laboratory and University of California at Davis
Type: Journal Article | Journal: International journal for parasitology. Parasites and wildlife | Year: 2016

Avian trichomonosis, caused by the flagellated protozoan parasite

Pierce B.M.,Idaho State University | Bleich V.C.,Idaho State University | Bleich V.C.,Wildlife Investigations Laboratory | Monteith K.L.,Idaho State University | Bowyer R.T.,Idaho State University
Journal of Mammalogy | Year: 2012

We studied mountain lions (Puma concolor) and mule deer (Odocoileus hemionus) inhabiting a Great Basin ecosystem in Round Valley, California, to make inferences concerning predatorprey dynamics. Our purpose was to evaluate the relative role of top-down and bottom-up forcing on mule deer in this multiple-predator, multiple-prey system. We identified a period of decline (by 83) of mule deer (19841990), and then a period of slow but steady increase (19911998). For mule deer, bitterbrush (Purshia tridentata) in diets, per capita availability of bitterbrush, kidney fat indexes, fetal rates (young per adult female), fetal weights, and survivorship of adults and young indicated that the period of decline was typical of a deer population near or above the carrying capacity (K) of its environment. Numbers of mountain lions also declined, but with a long time lag. The period of increase was typified by deer displaying life-history characteristics of a population below K, yet the finite rate of growth (λ 1.10) remained below what would be expected for a population rebounding rapidly toward K (λ 1.151.21) in the absence of limiting factors. Life-history characteristics were consistent with the mule deer population being regulated by bottom-up forcing through environmental effects on forage availability relative to population density; however, predation, mostly by mountain lions, was likely additive during the period of increase and thus, top-down forcing slowed but did not prevent population growth of mule deer. These outcomes indicate that resource availability (bottom-up processes) has an ever-present effect on dynamics of herbivore populations, but that the relationship can be altered by top-down effects. Indeed, top-down and bottom-up forces can act on populations simultaneously and, thus, should not be viewed as a stark dichotomy. © 2012 American Society of Mammalogists.

McGrann M.C.,William Jessup University | Furnas B.J.,Wildlife Investigations Laboratory
Ecosphere | Year: 2016

Climate change is expected to disrupt the distribution and behavior of montane birds. Monitoring these impacts will be essential because the ecological efects of climate change are likely to be complex. Hiking trails that traverse montane regions provide an opportunity to effciently survey bird diversity along elevation and other ecological gradients, and these data can be used to model climaterelated vulnerabilities of avian communities. In 2010, we surveyed a 697-km segment of the Pacific Crest Trail in northern California, USA. We conducted point counts of birds at 404 sites during the breeding season when birds were readily detected by song and other vocalizations. To bolster our sampling efort, we lef automated recorders at approximately half of the sites to make recordings for later interpretation of bird vocalizations. Using a multispecies occupancy model, we investigated how relationships between richness and elevation and between vocal activity and daily temperature difered among three migratory guilds-residents, altitudinal migrants, and Neotropical migrants. We found that richness decreased with increasing elevation for residents and Neotropical migrants, whereas it increased for altitudinal migrants. As temperature increased, residents and altitudinal migrants curtailed their vocal activity, but Neotropical migrants did not reduce vocal activity even though this behavior is energetically expensive on hot days. We also found that total species within each of three elevation zones was greatest at middle elevations (1200-1900 m). Altogether, these fndings suggest that as global temperature rises there may be greater competition among birds previously separated by elevation and that Neotropical migrants may be at greater risk of heat stress during the breeding season. Furthermore, the conservation of structurally complex, middle-elevation forests could provide birds a refugium to the impacts of climate change. © 2016 McGrann and Furnas.

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