Journal of Wildlife Diseases最新文献

The parasitic mite Sarcoptes scabiei causes mange in nearly 150 species of mammals by burrowing under the skin, triggering hypersensitivity responses that can alter animals' behavior and result in extreme weight loss, secondary infections, and even death. Since the 1990s, sarcoptic mange has increased in incidence and geographic distribution in Pennsylvania black bear (Ursus americanus) populations, including expansion into other states. Recovery from mange in free-ranging wildlife has rarely been evaluated. Following the Pennsylvania Game Commission's standard operating procedures at the time of the study, treatment consisted of one subcutaneous injection of ivermectin. To evaluate black bear survival and recovery from mange, from 2018 to 2020 we fitted 61 bears, including 43 with mange, with GPS collars to track their movements and recovery. Bears were collared in triplicates according to sex and habitat, consisting of one bear without mange (healthy control), one scabietic bear treated with ivermectin when collared, and one untreated scabietic bear. Bears were reevaluated for signs of mange during annual den visits, if recaptured during the study period, and after mortality events. Disease status and recovery from mange was determined based on outward gross appearance and presence of S. scabiei mites from skin scrapes. Of the 36 scabietic bears with known recovery status, 81% fully recovered regardless of treatment, with 88% recovered with treatment and 74% recovered without treatment. All bears with no, low, or moderate mite burdens (<16 mites on skin scrapes) fully recovered from mange (n=20), and nearly half of bears with severe mite burden (≥16 mites) fully recovered (n=5, 42%). However, nonrecovered status did not indicate mortality, and mange-related mortality was infrequent. Most bears were able to recover from mange irrespective of treatment, potentially indicating a need for reevaluation of the mange wildlife management paradigm.

As chronic wasting disease (CWD) continues to spread across North America, the relationship between CWD and host genetics has become of interest. In Rocky Mountain elk (Cervus elaphus nelsoni), one or two copies of a leucine allele at codon 132 of the prion protein gene (132L*) has been shown to prolong the incubation period of CWD. Our study examined the relationship between CWD epidemiology and codon 132 evolution in elk from Wyoming, USA, from 2011 to 2018. Using PCR and Sanger sequencing, we genotyped 997 elk and assessed the relationship between genotype and CWD prevalence estimated from surveillance data. Using logistic regression, we showed that each 1% increase in CWD prevalence is associated with a 9.6% increase in the odds that an elk would have at least one copy of leucine at codon 132. In some regions, however, 132L* variants were found in the absence of CWD, indicating that evolutionary and epidemiologic patterns can be heterogeneous across space and time. We also provide evidence that naturally occurring CWD is not rare in 132L* elk, which merits the study of shedding kinetics in 132L* elk and the influence of genotype on CWD strain diversity. The management implications of cervid adaptations to CWD are difficult to predict. Studies that investigate the degree to which evolutionary outcomes are shaped by host spatial structure can provide useful epidemiologic insight, which can in turn aid management by informing scale and extent of mitigation actions.

Animals colonizing novel environments can encounter novel hazards. Endangered San Joaquin kit foxes (Vulpes macrotis mutica) are found in the cities of Bakersfield and Taft in central California, USA. We documented 66 incidents of kit foxes becoming entangled in sports netting (e.g., soccer nets, batting-cage nets) occurring from the 1980s through 2022. Overall, 25 of the foxes died. Adults were more likely to get entangled in soccer nets, whereas pups (<1 yr) were more likely to get entangled in batting-cage nets. Pups are more likely to die while entangled, probably due to smaller body mass and lower energy reserves. The reasons that kit foxes get entangled in netting were unclear, although incidents involving batting-cage netting and pups may be due to natal dens being located under or near batting cages. At current rates, this hazard is unlikely to limit urban kit fox populations. However, losses of this endangered species should be minimized and the incidents are easily mitigated by dropping or lifting nets when not in use.

Hemotropic mycoplasmas (hemoplasmas) are opportunistic bacteria that attach to the erythrocyte surface, causing infectious anemia in several mammalian species, including rodents. Studies surveying native Azara's agoutis (Dasyprocta azarae) in Brazil are lacking. Accordingly, the present study aimed to assess hemoplasmas infection in free-ranging agoutis from an urban environmental conservation area in Curitiba, southern Brazil. Overall, 11/35 (31.43%) agoutis were positive to hemoplasmas by quantitative PCR (cycle threshold≤34.4). Sequencing of the 16S ribosomal RNA gene indicated Mycoplasma haemomuris infection, closely related to M. haemomuris subsp. ratti, suggesting hemoplasma transmission from urban rats to agoutis. Because the main route of M. haemomuris transmission has been direct rodent-to-rodent infection, the relatively lower positivity that we detected may be the result of low intraspecies contact due to the smaller social units of agoutis, generally consisting of two to four individuals, and low interspecies contact due to only sporadic agouti-rat interactions in urban settings, compared with other rodent species interactions. Further studies should be conducted to determine whether the hemoplasma infection that we found can cause clinical onset and life-threatening anemia in agoutis.

Mycobacteria of the Mycobacterium tuberculosis complex (MTC) are capable of infecting a wide variety of animals. Wild boar (Sus scrofa) has been recognized as an important wildlife reservoir for bovine tuberculosis. We screened wild boar in Slovenia for the presence of (1) Mycobacterium bovis in tissues and (2) antibodies to M. bovis in blood samples. In 2016 and 2017, 1284 tissue samples from 676 wild boar were subjected to cultivation. In 2018 and 2019, blood samples from 132 wild boar were examined using an ELISA kit. None of the MTC species were isolated from the tissue samples, and no antibodies to M. bovis were detected in the blood samples. Several nontuberculous mycobacteria (NTM), identified by 16S rRNA sequencing and/or matrix-assisted laser desorption ionization time-of-flight mass spectrometry, were found in the tissues of 9.8% of the wild boar: Mycobacterium nonchromogenicum, Mycobacterium peregrinum/Mycobacterium septicum, Mycobacterium avium, Mycobacterium engbaekii, Mycobacterium arupense, Mycobacterium algericum, Mycobacterium bohemicum, Mycobacterium confluentis, Mycobacterium flavescens, Mycobacterium fortuitum, Mycobacterium thermoresistibile, and Mycobacterium vaccae. Species-level identification was not possible for 21.2% of the isolates. At the time of the study, wild boar in Slovenia were not at risk from bTB; the significance of the presence of NTM in wild boar remains to be clarified and evaluated from a One Health perspective.

Humboldt Penguin (Spheniscus humboldti) population declines are attributable to several multifaceted anthropogenic impacts. At present, the exposure of Humboldt Penguins to high concentrations of heavy metals in the marine environment is a preeminent concern, due to mining along the Peruvian coast near key rookery sites. Metal and selenium concentrations were determined in eggs collected from September 2020 to April 2021 from a managed-care penguin population at the Brookfield Zoo to establish reference values for health indices conducted on wild populations. Concentrations of 16 elements, with emphasis on those found in mine efflux-arsenic, cadmium, copper, lead, mercury, selenium, and zinc-were assessed via inductively coupled plasma mass spectrometry in yolk, albumen, and eggshell. Data analyses indicate a clear delineation between egg constituents, with lipid-rich yolk displaying notably higher concentrations (μg/g) of arsenic (0.20 ± 0.064), chromium (0.086 ± 0.03), cobalt (0.01 ± 0.003), iron (238.65 ± 54.72), lead (0.32 ± 0.97), manganese (2.71 ± 0.66), molybdenum (0.57 ± 0.14), tin (3.29 ± 0.99), and zinc (64.03 ± 13.01) than other components (albumen and eggshell). These data confirm that heavy metals are partitioned differently across Humboldt Penguin egg components, which provides insight into the potential connection between embryonic nutrient source contamination and subsequent chick viability.

Segmental analyses of hair may be useful for measuring biomarkers over several seasons to years from a single sample. To attribute hair segments to specific time periods, a known chronological marker, or a hair growth rate, is needed. We examined guard hair growth rates of captive muskoxen (Ovibos moschatus) in Fairbanks, Alaska, USA. We sought to determine if a general growth rate could be applied across muskox populations, thus facilitating the use of segmental analyses for various biomarkers. We used archived samples from 16 muskoxen that had guard hairs sampled at six, 14, and 30 wk after shaving. We measured the lengths of 10 guard hairs per sample, calculated weekly and annual growth rates, and then fitted linear mixed-effects models to assess the effect of different covariates on hair growth rate. The period in which hair had been grown had a significant effect (P<0.05) on growth rate. Extrapolated annual hair growth rates were 277±40 mm/yr (weeks 0-6), 248±47 mm/yr (weeks 7-14), and 165±36 mm/yr (weeks 15-30), with an overall average rate of 210±14 mm/yr. These rates were significantly faster than those of free-ranging Greenland muskoxen-78 mm/yr as measured by stable isotope analyses-and varied intra-annually. This suggests that a universal growth rate cannot be generalized across muskox populations and time.

Sera from 391 waterbirds from eight USA states were tested for Toxoplasma gondii antibodies using the modified agglutination test. Fifteen different waterbird species (26.6%; n=104) were seropositive. Of the adults, 25.4% (n=52) showed a significantly higher T. gondii seroprevalence compared with juveniles (13.4%; n=17); however, sex was not a significant factor.

Once rodents have been successfully eradicated from Lord Howe Island, Australia, the critically endangered Lord Howe Island stick insect (Dryococelus australis (Montrouzier)) may be reintroduced, a century after it was thought to have become extinct. In captive populations of D. australis, elevated mortalities have been associated with bacterial pathogens. To better define the infectious risk posed by entomopathogens to the reintroduction program, we investigated the bacteria isolated from captive D. australis kept at Melbourne Zoo and on Lord Howe Island and from environmental samples and free-living invertebrates collected on various parts of the island. At Melbourne Zoo, Serratia and Pseudomonas spp. were the bacteria most frequently isolated between 2013 and 2019. Serratia spp. were also the organisms most frequently isolated from insects sampled in April 2019 from the captive population on Lord Howe Island. In addition, Serratia spp. were isolated from a range of environmental samples collected on Lord Howe Island during March-April 2019. These environmental isolates had a broader range of biochemical and molecular characteristics than those obtained from the captive insect populations. A large proportion of these isolates were urease positive and had biochemical profiles previously not described for Serratia spp. This study highlights the need for better surveillance for potential pathogens in understudied regions and sites. We conclude that infections caused by Serratia spp. might pose a problem to the captive breeding program for D. australis but that the risk of introducing novel pathogens to Lord Howe Island through infected insects is low. Our study explores some of the potential risks involved in captive breeding and provides a valuable example of using pathogen surveillance to better inform an invertebrate conservation program.