Journal of Wildlife Diseases最新文献

Monitoring wildlife health is essential for understanding global disease patterns, particularly as vector-borne infections extend the geographic ranges and thereby hosts due to environmental shifts. Anaplasma marginale, primarily impacting cattle, has economic implications and has been found in diverse hosts, yet its presence in capybaras (Hydrochoerus hydrochaeris), influential in tick-borne pathogen spread, lacks comprehensive understanding. From 2015 to 2022, 14 capybaras were surveyed across two different areas of northeastern Argentina. In 1 of 14 (7%) capybaras, the presence of A. marginale was confirmed through the amplification of specific genes, msp5 and msp1β. In addition, A. marginale DNA was detected in the capybara's blood sample through quantitative PCR, with a cycle threshold value of 30.81 (800 copies per reaction). Amplification of a fragment of the msp1α gene revealed PCR products of three different sizes, suggesting the presence of at least three coinfecting A. marginale variants in the capybara host. This study suggests that capybaras are wild hosts for A. marginale in the Ibera Wetlands in Argentina, potentially influencing the infection dynamics of both domestic and wild species. This finding highlights the necessity for thorough studies on the role of capybaras in disease dynamics, crucial for understanding wildlife health and the spread of disease.

Soft ticks in the genus Ornithodoros occur throughout the Mojave Desert in southern Nevada, southeastern California, and parts of southwestern Utah and northwestern Arizona, USA, and are frequently observed parasitizing Mojave desert tortoises (Gopherus agassizii). However, limited research exists examining the relationship between ticks and desert tortoises. Mojave desert tortoises are listed as threatened by the US Fish and Wildlife Service, and as such, their populations are monitored and individual tortoise health is routinely assessed. These health assessments document the presence and abundance of ticks present on tortoises, but detailed examination of the relationship between ticks and tortoise health has been lacking. This study analyzed the relationship between tick presence and desert tortoise health assessments as a function of season, location, age (adult vs. juvenile), foraging behavior, evidence of clinical signs of disease, body condition score, and sex. Our results indicate that more ticks were found on tortoises in the summer than in any other season. Ticks were observed more frequently on captive tortoises versus wild tortoises, and more ticks were likely to be present on adult tortoises than on juveniles. Ticks were also more likely to be observed on tortoises that lacked evidence of foraging and on tortoises with observed clinical signs of disease. These findings provide valuable insights into the biology of ticks in relation to tortoises that may be useful for management of both captive and free-living threatened tortoise populations where ticks are detected. Our study also may improve understanding of potential tick-borne disease dynamics in the Mojave desert tortoise habitat, including Borrelia sp. carried by Ornithodoros ticks, which cause tick-borne relapsing fever in people.

Invasive species threaten wildlife. We detected invasive ticks on wildlife and indigenous ticks on invasive mammals in southern Brazil. The invasive cattle tick Rhipicephalus microplus was found on 12 native mammals and one invasive exotic (Axis axis). The Neotropical tick Amblyomma dubitatum was found on three invasive alien mammal species.

Toxoplasma gondii, a parasitic protozoan, may infect most warm-blooded animals, including humans and carnivores. Our study focused on alien-invasive American minks (Neogale vison) and domestic cats (Felis catus) in the Valdivian Temperate Rainforest, Chile. The main goal was to investigate the relationship between their dietary habits and T. gondii exposure in the Valdivia River watershed. To detect T. gondii exposure, blood serum samples from 49 domestic cats and 40 American minks were analyzed using an ELISA, and stable isotope analysis of δ15N and δ13C from vibrissae was performed to determine the dietary habits of both species. Relationships between T. gondii exposure and dietary habits were explored using generalized linear mixed-effects models. American minks that were T. gondii seropositive exhibited a broader prey range compared to seropositive domestic cats, with minimal dietary overlap between the two groups. Exposure of domestic cats to T. gondii had no significant association with any isotope value or prey item in their diet. In American minks, we found a positive and significant association between the proportion of Domestic chicken (Gallus gallus domesticus) in the diet and high δ15N values with T. gondii exposure. This suggests that domestic species prey related to anthropogenic areas, and the consumption of high-trophic-level prey, may contribute to T. gondii exposure in American minks. Conversely, contrary to previous hypotheses, consumption of rodents showed no significant association with T. gondii exposure in either species. Our findings emphasize the importance of further research to investigate trophic interactions in the transmission dynamics of T. gondii in the Valdivian Temperate Rainforest.

Chronic phalaris toxicity (CPT) is a neurological disease caused by animals ingesting toxins produced by early growth stages of Phalaris aquatica, a pasture plant introduced to the southeastern regions of Australia post colonization. Little is known about the clinical progression of CPT in wildlife, as incidents are sporadic and predominantly reported when animals are in the end stages of disease and in a poor welfare state. We studied a cohort of 35 eastern gray kangaroos (Macropus giganteus) affected by CPT to clarify clinical prognosis and survival rates. Kangaroos were captured in May, June, and July of 2022 at Plenty Gorge Parklands, Victoria, Australia. Each animal was radiotracked for 180 d, clinical progression and disease outcomes monitored twice a week. By the conclusion of the study, 24 animals had died (19 by euthanasia due to deterioration, five found dead). Ten animals survived, with two demonstrating a reduction in clinical signs and eight showing full resolution of clinical signs. One animal was disqualified from the study. The overall survival rate was 29.4% (95% confidence interval 17.5-49.5%). The survival duration of animals that died ranged from 5 to 133 d. There was no difference in survival rate based on sex (P=0.2), age class (P=0.49) or the month of capture (P=0.49). These results suggest that CPT is an important health and welfare concern for at-risk macropod populations, with high case-fatality rates and prolonged clinical durations. Further research to manage the disease via methods such as reducing Phalaris aquatica plant coverage and preventative treatments for animals is warranted to reduce disease incidences and improve disease outcomes in wildlife populations.

Natural history collections have long served as the foundation for understanding our planet's biodiversity, yet they remain a largely untapped resource for wildlife disease studies. Extended specimens include multiple data types and specimen preparations that capture the phenotype and genotype of an organism and its symbionts-but preserved tissues may not always be optimized for downstream detection of various pathogens. Frogs are infected by an array of pathogens including Batrachochytrium dendrobatidis (Bd), Ranavirus (Rv), and Amphibian Perkinsea (Pr), which provides the opportunity to study differences in detection dynamics across tissue types. We used quantitative PCR protocols to screen two tissue types commonly deposited in museum collections, toe clips and liver, from two closely related host species, Rana catesbeiana and Rana clamitans. We compared Bd, Rv, and Pr infection prevalence and intensity between species and tissue types and found no significant difference in prevalence between species, but Bd intensity was higher in R. clamitans than R. catesbeiana. Toe tissue exhibited significantly higher Bd infection loads and was more useful than liver for detecting Bd infections. In contrast, Rv was detected from more liver than toe tissues, but the difference was not statistically significant. Our results support the use of extended specimen collections in amphibian disease studies and demonstrate that broader tissue sampling at the time of specimen preparation can maximize their utility for downstream multipathogen detection.

As part of an epidemiologic study of the Zika virus (ZIKV) in deer (Cervidae), samples from 56 captive deer in south and southeastern Brazil were tested for evidence of ZIKV. Three samples were positive using reverse-transcription quantitative PCR, although no samples were positive by virus isolation.

Urban sprawl threatens biodiversity and is responsible for significant changes in the species that live in these environments. Given the high cost of comprehensive surveillance, monitoring disease indirectly, such as detecting skin lesions in birds, may help us better understand the prevalence of diseases affecting wild populations. We assessed the frequency of leg skin lesions, as a proxy of disease presence, in 1,565 individuals of 25 species, along the urban matrix of a large Neotropical city, Brasília, Federal District, Brazil. We tested the hypothesis that there is an increase in the frequency of skin lesions in birds due to urban intensification. We observed an increasing trend in some bird species between the frequency of occurrence of lesions and the intensity of urbanization. Species with a higher number of captures had an increase in the percentage of lesions, indicating that the occurrence of lesions may be linked to higher population density or that detection of the effect occurs only when sample sizes are high and controlled among urbanization categories. Our study highlights how the intensity of urbanization may increase the risk of disease transmission for these species. Unfortunately, studies on this topic are scarce in Neotropical regions, despite the region's high biodiversity and urban expansion.

Pathogens not only cause mortality but also impose nonlethal fitness consequences. Snakes experience trade-offs associated with behaviors that combat disease but divert time and energy away from other critical activities. The impacts of such behaviors on fitness remain poorly understood, raising concerns amid the emergence of novel herpetofaunal diseases. Ophidiomycosis, caused by the ascomycete fungus Ophidiomyces ophidiicola, impacts free-ranging snakes across North America and has been implicated in declines of several imperiled populations. Although previous ophidiomycosis research has primarily focused on disease-related mortality, few studies have evaluated nonlethal impacts on snake fitness. To address this knowledge gap, we investigated the effects of apparent ophidiomycosis on the behavior, habitat use, and movement of snakes in central New Jersey, USA, from 2020 to 2021. Our focal species was the eastern copperhead (Agkistrodon contortrix), a state species of special concern with limited representation in the ophidiomycosis literature. Although we did not observe mortality in our study population, we found that copperheads with apparent ophidiomycosis (8/31 individuals) displayed significantly different thermoregulatory behaviors than snakes without ophidiomycosis. Specifically, individuals with apparent ophidiomycosis favored areas with less canopy cover, less rock cover, and more coarse woody debris. Our findings suggest that snakes with apparent ophidiomycosis select habitats conducive to initiating behavior-mediated fever, potentially facilitating recovery.

The intracellular pathogens Toxoplasma gondii, Brucella spp., and Chlamydia spp. are all known causative agents of abortion in wildlife. Both T. gondii and Brucella spp. have been identified in marine mammal abortions and a limited number of studies have detected their potential presence in Australian fur seals (Arctocephalus pusillus doriferus), but data are sparse for these pathogens in Australian fur seal breeding colonies. Australian fur seals have been shown to have a high degree of third-trimester pregnancy loss in one of their largest breeding colonies. Additionally, pup production has declined at the largest breeding colony for the species. This study surveyed the presence of T. gondii, Brucella spp., and Chlamydia spp. as potential infectious causes of this reproductive loss. Aborted fetuses were collected from two of the largest breeding colonies for the species, Seal Rocks (n=19) and Kanowna Island (n=34). These were examined grossly and through histopathological evaluation, in conjunction with molecular testing for all three pathogens. Placentas were collected from full-term births during the pupping season from Kanowna Island (n=118). These were used to compare the molecular prevalence of the three pathogens in presumed successful pregnancies. Chlamydia spp. was not detected in aborted fetuses in this study. Brucella spp. was detected with PCR in both aborted fetuses (9.4%) and placentas from full-term births (3.4%), and T. gondii was detected using routine histopathology (n=2/53), immunohistochemistry (n=3/4), and PCR (n=4/53) in tissues from aborted fetuses. Toxoplasma gondii was present in 7.5% of third-trimester abortions and absent from all full-term placentas. Brucella spp. was detected in both aborted fetuses and full-term placentas. This is the first description of vertical transmission of T. gondii in a marine mammal from the southern hemisphere.