Barren-ground caribou of the subspecies Rangifer tarandus granti are distributed throughout Alaska, USA, and the Yukon, Canada. The acute phase response is an innate immune response activated due to inflammatory stimulus, resulting in changing levels of acute phase proteins, including haptoglobin (Hp) and serum amyloid A (SAA). Haptoglobin and SAA are used as indicators of inflammation in domestic species, with several studies demonstrating their use in wildlife. In this study, banked serum samples from apparently clinically normal free-ranging barren-ground caribou (reference group) were used to establish reference intervals (RI) for Hp and SAA in caribou. These RIs were compared with additional samples from a declining herd with ongoing Brucella suis biovar 4 transmission. The RIs for Hp and SAA with 90% upper confidence intervals were 0.12-1.03 (0.08-1.27) mg/mL and 0.10-18.44 (0.10-31.00) mg/L, respectively. The SAA levels in the declining herd were found to be significantly elevated from the reference group (P=0.009), whereas no difference was found in Hp levels between the two herds (P=0.389). Meanwhile, SAA and Hp levels in animals with B. suis biovar 4 titers ≥1:80 were significantly elevated from the reference group (SAA P<0.001; Hp P=0.178). The results of our study indicate that SAA and Hp hold promise in monitoring the overall herd health of caribou in Alaska.

Previous studies have examined prevalence of leprosy-causing bacteria, Mycobacterium leprae and Mycobacterium lepromatosis, in rural Mexican long-nosed armadillo (Dasypus mexicanus) populations of the southeastern USA. However, few prevalence studies have been conducted in Alabama nor in urbanized, human-dominated areas where potential zoonotic transmission may be a public health concern. This study evaluated the prevalence of leprosy-causing bacteria in armadillos from rural, suburban, and urban zones in Lee and Mobile County, Alabama, USA. This study detected the first evidence of M. leprae-infection in a wild juvenile armadillo, from an individual sampled in a suburban zone of Mobile County, indicating potential vertical or environmental transmission. Additionally, 15/83 adult armadillos were infected in the Mobile County population, giving a total population prevalence of 16/93 (17%). Of the adults, more females were infected with M. leprae (11/36), especially lactating females, compared to males (4/47), despite more adult males being sampled overall. In Lee County, 64 adults were sampled and only one, a male, was M. leprae-positive, resulting in a total population prevalence of 1/94 (1%). The significantly lower occurrence than in Mobile County may be a result of environmental conditions, as the counties predominantly exist in two different ecoregions, the Piedmont and Southeastern Plains. Therefore, this study presents findings that may support an ecological-constraints hypothesis, previously applied to the northward expansion of M. leprae. Although no significant difference in prevalence was observed among the residential zones in this study, future research should investigate the prevalence of leprosy-causing bacteria in armadillos across different ecoregions and land use types to elucidate transmission dynamics and zoonotic risk, and inform public health strategies and wildlife management efforts in the southeastern USA.

During a 1-mo period in early 2023, four adult free-ranging mountain lions (Puma concolor) and two adult free-ranging bobcats (Lynx rufus) died or were euthanized during an outbreak of H5N1 highly pathogenic avian influenza virus (HPAIV) in Colorado, USA. All six animals tested positive for HPAIV clade 2.3.4.4b, and necropsy findings resembled those described by others for domestic cats and wild felids infected with HPAIV clade 2.3.4.4b in North America. The most consistent findings in the Colorado wild felids were necrotizing and lymphoplasmacytic meningoencephalitis (6/6) and interstitial to bronchointerstitial pneumonia (3/6). Necrotizing lesions were also identified in other tissues, including liver (3/6) and adrenal gland (2/4). Immunohistochemistry demonstrated localization of influenza A-specific antibody to necrotizing lesions. Sequencing of the HPAIV PB2 gene did not reveal mutations to suggest mammalian adaptation, and resolution of the outbreak in wild felids coincided with a decline in cases in wild birds. The presumed mechanism of transmission to wild felids was exposure at the time of ingestion of infected avian carcasses. Immunohistochemistry of tongue, pinna, and skeletal muscle did not indicate utility of these samples for noninvasive sampling of hunter-harvested carcasses for HPAI surveillance. We recommend testing brain tissue for HPAIV surveillance in wild felids.

Understanding the factors that influence wildlife disease spread can help inform monitoring and mitigation efforts. Rabbit hemorrhagic disease virus 2 (RHDV2) infection is a highly contagious viral disease that is usually fatal for rabbit and hare species. We obtained RHDV2 infection case counts for wild lagomorph species from 2020-24 across 14 USA states, from a publicly available USA Department of Agriculture Animal and Plant Health Inspection Service dataset. We used Bayesian conditional autoregressive models to assess the effects of land cover, domestic RHDV2 infection case counts, and environmental factors on wild RHDV2 infection case counts. Our findings suggested that wild RHDV2 cases were positively related to RHDV2 cases in domestic lagomorphs, developed land cover, and lower annual precipitation. These results can be used to target RHDV2 surveillance in wild lagomorphs to urban areas where RHDV2 has been detected in domestic lagomorphs. Overall, our study provides insights into where surveillance could be prioritized to better understand the spread of RHDV2 into new areas.

Astroviruses (AstVs) are RNA viruses infecting a wide range of vertebrates, with increasing evidence of cross-species transmission. We investigated the presence of AstVs in the Réunion Harrier (Circus maillardi), a critically endangered raptor endemic to Réunion Island. Cloacal and oropharyngeal swabs were collected from 133 individuals sampled between 2015 and 2024. Reverse transcription and seminested conventional PCR was used to detect the AstV RNA-dependent RNA polymerase gene. In total, 5.3±3.8% of birds tested positive, with no significant association with age, sex, or sampling method. All positive samples were obtained from wild-caught individuals except one detected from a bird at the care center. Phylogenetic analysis revealed that all sequences were genetically related to rodent-associated AstVs previously detected on Réunion Island and in Madagascar, and they did not cluster with avian lineages. These findings are consistent with previous results in the endemic Réunion free-tailed bat (Mormopterus francoismoutoui). For Réunion Harriers, they further suggest recurrent exposure to nonnative rodent-associated viruses through predation. The pathogenic potential of such viruses in wildlife remains unknown, but it could be amplified in insular species lacking prior exposure or coevolutionary history. Our results support the need to better integrate wildlife disease surveillance into island conservation strategies.

The collared peccary (Pecari tajacu) is a member of the Tayassuidae family widely distributed throughout the Americas, particularly in Brazil. These animals have important ecologic functions and, despite their good conservation status, are frequently affected by anthropogenic pressures. Candida spp. are commensal yeasts present in the microbiota of various hosts; however, under conditions that disrupt microbial balance, they can become opportunistic pathogens. Some Candida spp. are also of great relevance to the One Health framework, because they cause significant impacts on the health of humans and animals. The investigation of potentially zoonotic fungi in wild animals is fundamental for understanding the ecoepidemiologic dynamics, so this study aimed to detect Candida spp. in captive collared peccaries bred in naturalistic enclosures in the Brazilian Amazon. Swabs from the oral cavity were collected and processed according to classical microbiology techniques. Thirty animals were evaluated, and 93% (28/30) had at least one Candida species detected. A total of 42 Candida spp. isolates were recovered, with five identified species: Candida albicans, Candida krusei, Candida parapsilosis, Candida glabrata, and Candida tropicalis. One Candida isolate remained unidentified. These findings highlight the role of collared peccaries as potential reservoirs of opportunistically pathogenic yeasts and emphasize the importance of active surveillance of microbial diversity in wild animals.

Molecular investigation of the occurrence of herpesviruses in 228 wild birds in Piauí, northeastern Brazil, identified a herpesvirus in a migratory Wilson's Plover (Charadrius wilsonia). Genetic analysis supported its classification as a new strain, tentatively named Charadrius alphaherpesvirus 1, within the genus Mardivirus, broadening the herpesvirus host range in Charadriiformes.

Opportunistic examination of reptiles in the context of various research projects in Florida, USA identified infection with the pentastome Raillietiella orientalis in novel hosts, including free-ranging and captive animals. Free-ranging hosts included two species of invasive snakes (Boa constrictor and Python sebae), three native snakes (Thamnophis saurita, Lampropeltis elapsoides, and Micrurus fulvius), two invasive lizards (Anolis equestris and Basiliscus vittatus), and one native lizard (Aspidoscelis sexlineatus). The latter represents the first documented case of adult R. orientalis spillover into Florida's native lizards. Novel definitive non-indigenous hosts in captive settings were one lizard species (Pogona vitticeps) and one tortoise (Aldabrachelys gigantea). The documented Raillietiella infection in a tortoise not only represents a substantial host jump to include an additional order, the testudines, but it also demonstrates the pathogenic potential of the parasite in tortoises. Developing effective biosecurity strategies is essential for safeguarding both captive and wild herpetofauna from continued R. orientalis spillover, especially in regions with proximity to and trade with Florida.

Turtle acanthocephalans are a depauperate group of helminths, yet they parasitize a quarter of all turtle species in North America. Despite acanthocephalans being common in turtles, their potential as disease-causing agents remains unknown. In other vertebrate hosts, acanthocephalans are known to cause pathologic changes upon attachment (via with their armed proboscis) to the intestinal wall of the host. Herein, we report new turtle host associations, ultrastructural characterization, and molecular data for turtle acanthocephalans. However, the primary goal of this study was to evaluate whether there is pathology associated with acanthocephalans in turtle hosts. In total, 63 turtles comprising six sampled species were examined for acanthocephalans via surveillance of wild turtles in Oklahoma, USA, between 2010 and 2022. A mean intensity of 395 acanthocephalans per turtle was recovered from 30 (83%) of 36 red-eared sliders (Trachemys scripta elegans), morphologically and molecularly identified as Neoechinorhynchus chrysemydis (n=382), Neoechinorhynchus emydis (n=187), Neoechinorhynchus emyditoides (n=1,803), and Neoechinorhynchus pseudemydis (n=2,901). Only one (11%) of nine snapping turtle (Chelydra serpentina) was infected with acanthocephalans, morphologically and molecularly identified as juveniles of N. chrysemydis (n=1) and Neoechinorhynchus cylindratus (n=12), a fish acanthocephalan. Histopathologic examination revealed changes to the intestinal walls of infected red-eared sliders, including villous atrophy and excessive mucus production. Additionally, the presence of boluses of worms expelled within turtle feces was observed. Noninfected turtles showed no evidence of gross or histopathologic lesions in the intestines. Overall, these findings indicate that acanthocephalans can potentially elicit pathologic changes to turtle hosts, probably as a result of intestinal irritation due to acanthocephalan attachment.

Birds are host to four orders of parasitic insects: flies (Diptera), lice (Psocodea: Phthiraptera), true bugs (Hemiptera), and fleas (Siphonaptera). These parasites can lower host fitness and thus require birds to invest in defenses to minimize fitness losses. In Puerto Rico, virulent parasites, such as Philornis spp. flies, threaten endangered species and subspecies of birds. Philornis larvae are hematophagous and burrow beneath the skin of both nestling and adult birds. Unfortunately, little is known regarding the prevalence and intensity of subcutaneous Philornis flies of adult birds in Puerto Rico. Here, we inspected 430 birds, representing 38 species, for Philornis infestation. We found Philornis larvae on only four birds, despite previous studies reporting high Philornis prevalence on adults of a single Puerto Rican species, Pearly-eyed Thrashers (Margarops fuscatus). Our results are consistent with other studies suggesting that the prevalence and intensity of Philornis is low in most adult and fledgling birds, compared to nestlings. Our data suggest that Philornis infestation is not a major threat to adult birds in Puerto Rico. In contrast, we show that parasitic lice are relatively common on Puerto Rican birds. Of 309 birds dusted for ectoparasites, 163 (53%) were infested with lice. None of the 309 birds were infested with parasitic fleas or bugs. Our results confirm other recent work showing relatively high prevalence and intensity of lice on birds in humid regions of the world.