Journal of Wildlife Diseases最新文献

In Costa Rica, human-tapir conflicts are increasing, including disease transmission, as Baird's tapirs (Tapirus bairdii) move into human-altered landscapes. We investigated the death of a wild male tapir, identifying a systemic Actinomyces israelii infection. The potential of this pathogen being an emerging health threat for tapir conservation warrants further study.

Ospreys (Pandion haliaetus), piscivorous raptors with extensive global distributions, can undergo extensive migrations. Migratory species can transport ectoparasites, including ticks, to new regions. Many soft ticks (Argasidae) are ornithophilic and occur in bird nests, occasionally causing nest abandonment and chick mortality through pathogen transmission, blood loss, or paralysis. Argas spp. soft ticks are distributed worldwide, with several species in the USA, predominately in the western USA. Argas (Persicargas) giganteus, has been documented on numerous passerine and raptor species in the western USA and parts of Mexico. We detected A. giganteus on two Ospreys from Pennsylvania and Washington, DC, USA, representing a significant recognized range expansion. Genetic analysis confirmed that ticks from both birds were A. giganteus: internal transcribed spacer 2, 12S rRNA, and 16S rRNA gene sequences were 100, 100, and 99.7% similar to A. giganteus, respectively. Most ticks tested (7/8, 88%) were Rickettsia spp. positive; six sequences were Rickettsia hoogstraalii, with one most similar (99.5%) to Rickettsia monacensis. Although A. giganteus is not known to infest people, R. monacensis is a cause of spotted fever rickettsiosis; the pathogenicity of R. hoogstraalii in humans is poorly understood. Furthermore, A. giganteus can probably cause tick paralysis in raptors, especially in young birds. Therefore, continued surveillance for A. giganteus and Rickettisa spp. is warranted, particularly because this tick and associated pathogens seem to be emerging in the eastern US.

Few studies exist in which host-pathogen systems have been studied within months of their emergence and followed for many years, making it possible to test the virulence-transmission hypothesis and to determine if a pathogen becomes more or less virulent over time. Around 1994 the bacterium Mycoplasma gallisepticum jumped from poultry to House Finches (Haemorhous mexicanus) and other wild birds in the US. Bacterial virulence increased as it rapidly spread across eastern North America, causing House Finch abundance to decline by half. The new M. gallisepticum variants that eventually colonized the western US had lost a substantial part of their genome and had a reduced virulence. In our study, initial survival of M. gallisepticum was lower in eastern US than in western US isolates, and birds with a higher bacterial load showed higher transmission rates, but this relationship differed between birds inoculated with eastern versus western isolates. Western isolates were less pathogenic (similar pathogen loads caused less-severe disease) than eastern isolates and had lower transmission rates for a given bacterial load. Our study provides insights into how pathogens spreading after a host shift and across a continent may respond to novel evolutionary pressures in diverse ways.

Amphibians are experiencing extinction rates over 200 times the background extinction rate. One emerging infectious disease contributing to amphibian declines is caused by the fungal pathogen Batrachochytrium salamandrivorans (Bsal), which has caused mass die-offs of fire salamanders (Salamandra salamandra) in Europe and could pose a major threat to North American salamander biodiversity if introduced to the continent. A recent study investigated the effects of pathogen dose and environmental temperature on Bsal chytridiomycosis disease progression in wild-caught Notophthalmus viridescens (eastern newts). During that study, necropsy and histologic examination revealed that many newts were infected with multiple parasites. We performed a retrospective analysis on the 41 eastern newts from that study to evaluate whether parasite load was related to Bsal load, environmental temperature, or host survival. In this study 34% (15/41) of newts were infected with nematodes and 22% (9/41) were infected with protozoans. Nematode loads were greatest in newts held at cooler temperatures. Additionally, there was a significant correlation between the overall parasite load and the survival time of newts infected with Bsal. Our results suggest that environmental temperature and parasite infection may interact to increase infection tolerance, which is consistent with recent results reported for Batrachochytrium dendrobatidis. Our results highlight the importance of studying micro- and macroparasite interactions and their possible impacts on host survival.

There is evidence that both domestic and wild animals are susceptible to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the virus causing COVID-19 in humans. However, the extent of infection in native wild mammals and the most susceptible species to SARS-CoV-2 remain unclear. We assessed SARS-CoV-2 exposure in native wild mammals from the Misiones region, a subtropical area in northeastern Argentina, within the Upper Paraná Atlantic Forest ecoregion. A descriptive, cross-sectional study was designed using serum samples from wild mammals that entered the Centro de Rescate, Rehabilitación y Recría de Fauna Silvestre Güirá Oga for veterinary care between December 2019 and March 2022. Epidemiological data were obtained from veterinary records, and antibodies against SARS-CoV-2 were detected using a novel bridge multispecies ELISA. A total of 115 serum samples from 26 wild mammal species were analyzed, revealing antibodies in 20 samples and a seroprevalence of 17.4% (95% confidence interval 11.5-25.3%). Antibodies were detected in 13 species, including native wild mammals in Argentina. These findings indicate that certain wildlife species may be infected by this virus, but do not provide evidence that any of the tested animals are reservoirs for SARS-CoV-2, as the study only addressed exposure. The results underscore the importance of continued surveillance to understand the ecological impacts of SARS-CoV-2, prevent zoonotic transmission, and protect both wildlife and human health.

We investigated blood from 39 free-ranging Marsican brown bears (Ursus arctos marsicanus), a critically endangered brown bear subspecies. Bears were 1-15 yr old and sampled from January 1991 to May 2023. We found significantly lower mean corpuscular hemoglobin and mean corpuscular volume in subadults than in adults (P<0.10) and higher cholesterol (P<0.10) in males than in females.

Coyotes (Canis latrans) can serve as hosts for many pathogens of concern and may be useful for monitoring the prevalence and emergence of these pathogens. We collected serum and/or whole blood antemortem from 43 coyotes from South Carolina, USA, and collected samples from opportunistically collected carcasses from 71 Tennessee, USA and 15 South Carolina, USA coyotes. We tested samples with SNAP 4Dx PLUS rapid ELISA tests for Ehrlichia spp., Anaplasma spp., Dirofilaria immitis, and Borrelia burgdorferi and with microscopic agglutination tests for Leptospira spp. Real-time and conventional PCR for B. burgdorferi were performed on Ixodes scapularis ticks from Tennessee coyotes, detecting B. burgdorferi DNA in 5% of tested ticks. We found 43% (28/65) of Tennessee coyotes were seropositive for B. burgdorferi compared to only 2% (1/52) of South Carolina coyotes. Coyotes were also seropositive for Ehrlichia spp. (66% [43/65] in Tennessee; 21% [11/52] in South Carolina) and Anaplasma spp. (26% [14/65] in Tennessee). Three Tennessee coyotes were PCR-positive for Leptospira spp., including two sequences most similar to Leptospira santarosai and one most similar to Leptospira interrogans. A total of 25% of coyotes (23/91) were seropositive for Leptospira spp., and interstitial nephritis was associated with Leptospira spp. seropositivity. This study demonstrates the expanded geographic range of B. burgdorferi in the southeast and the high prevalence of zoonotic pathogens in the coyote populations of Tennessee and South Carolina.

North American bison (Bison bison) face significant challenges to their recovery, including disease risks associated with translocation and genetic bottlenecks. This study aimed to achieve a multidisciplinary consensus on a definition of bison health and to identify key infectious disease concerns linked to bison translocation. A two-round Delphi survey was conducted with 12 of 22 invited experts representing public, tribal, nonprofit, and private sectors. Participants defined bison health as the ability of populations to express natural behaviors, demonstrate resilience to external stressors, and achieve high reproductive output within their environment with minimal intervention. Mycoplasma bovis was identified as a high-priority pathogen due to its severe economic and health impacts. This definition of bison health may be useful as a basis for guiding health monitoring and informing policy as well as identifying key needs of the bison sector.

Human activities, such as habitat fragmentation, have displaced wild birds into urban and agricultural areas, increasing their exposure to enteric pathogens through contaminated food and water. Molting stress further heightens their susceptibility to infection. This study examined 1) the presence of Klebsiella pneumoniae, Salmonella enterica serovar Typhimurium, Listeria monocytogenes, and Campylobacter jejuni in fecal samples from Violet-Crowned (Ramosomyia violiceps) and Broad-Billed (Cynanthus latirostris) Hummingbirds across two environments: disturbed forest and urban; 2) potential associations with contamination sources (wastewater, rivers, water bodies, and livestock feces); and 3) the effects of molting. Fecal samples were analyzed using real-time PCR and Bayesian generalized linear mixed models to evaluate five response variables: individual pathogen presence [corresponds to the 3 pathogens (K. pneumoniae, S. enterica, and L. monocytogenes)], combined pathogen presence, and pathogen copresence. Predictors included hummingbird species, molt, environment type, and distance to contamination sources. Of the bacteria, K. pneumoniae exhibited the highest prevalence (46%), followed by S. enterica (9.5%) and L. monocytogenes (7.9%); C. jejuni was not detected. Results indicated that 1) R. violiceps had approximately threefold higher odds of K. pneumoniae presence than C. latirostri and 2) molting individuals had 6.5-fold higher odds of carrying at least one pathogen. Neither environment type nor distance to contamination sources showed significant effects. The high prevalence of K. pneumoniae highlights the urgent need to preserve natural habitats and reduce anthropogenic pressures on wild bird populations. Molting increases susceptibility to gastrointestinal pathogens, while species-specific differences suggest variable resistance mechanisms. These findings underscore the importance of 1) habitat conservation to minimize pathogen exposure, 2) urban green space management with strict hygiene protocols for artificial feeders, and 3) integrated wildlife pathogen surveillance within One Health frameworks.

Wild pig (Sus scrofa) populations are expanding across the USA, raising concerns about the ecologic impacts and role as reservoirs for pathogens of significance to human and animal health. Trypanosoma cruzi, the causative agent of Chagas disease, is a recognized risk for humans and domestic dogs in the southern USA. Common wildlife reservoirs of T. cruzi include rodents (e.g., Neotoma spp.), raccoons (Procyon lotor), and Virginia opossums (Didelphus virginiana); however, there have been reports of T. cruzi infection in suids, including a domestic pig (Sus scrofa domesticus) in Mexico and three wild pigs in Texas, USA. Our study aimed to better understand the prevalence and distribution of T. cruzi antibodies in wild pigs in the USA. We collected 1,093 serum samples from wild pigs across 12 states in the southern, midwestern, and western regions of the USA, all of which have populations of T. cruzi triatomine vectors. We tested sera for antibodies against T. cruzi using an indirect ELISA and detected an overall apparent prevalence of 14.6% (160/1,093; 95% confidence interval, 12.6-16.9%). Pig sex, age class, month of sampling, and region were not significantly associated with seroprevalence; however, state of origin explained some variation in the data. We demonstrated that wild pigs in the USA were exposed to T. cruzi, highlighting the need for further research elucidating their role in T. cruzi transmission.