Necropsy of a Réunion Harrier (Circus maillardi), August 2023, revealed adult trematode fragments and eggs associated with severe hepatobiliary lesions. The trematode was confirmed as Platynosomum illiciens by PCR and DNA sequencing. This case raises potential conservation concerns for this endangered raptor and highlights the need for further epidemiologic investigations.

Canine distemper virus (CDV), a morbillivirus with a broad host range, has increasingly been reported in wildlife, including nonhuman primates. However, data on CDV infection in free-ranging Neotropical primates remain limited. Herein, we describe the pathologic, immunohistochemical, and molecular findings associated with CDV infection in three free-ranging black-tufted marmosets (Callithrix penicillata) from periurban areas of Palmas, Tocantins state, Brazil Between February and March 2023, residents reported sick or dead marmosets with facial cutaneous lesions. Postmortem examination revealed mucocutaneous lesions and pulmonary changes. Histologically, all animals exhibited moderate-to-severe interstitial pneumonia characterized by mononuclear inflammation, marked type II pneumocyte hyperplasia, necrotizing bronchiolitis, and multinucleated syncytial cells. Additional findings included epithelial degeneration and ulceration, viral inclusions in the skin and esophagus, and lymphoid depletion in the spleen. Eosinophilic intranuclear and intracytoplasmic inclusion bodies were observed in epithelial cells and macrophages. Immunohistochemistry demonstrated multifocal CDV antigen labeling in pulmonary and esophageal tissues, whereas tests for yellow fever virus, human alphaherpesvirus, and Toxoplasma gondii were negative. Molecular analysis confirmed CDV infection by amplification of short fragments of the conserved L gene, which showed ≥98% nucleotide identity with Brazilian strains. However, further sequencing was not possible due to nucleic acid degradation. These findings expand current knowledge of CDV infection in Neotropical primates and highlight the importance of integrated wildlife surveillance at the human-domestic animal-wildlife interface.

We describe the diagnostic utility of peripheral tissues from naturally infected free-ranging rabid striped skunks (Mephitis mephitis) to explore enhanced rabies surveillance testing using alternative tissues to the brainstem. Fifty-two dead or moribund adult striped skunks were collected by the Larimer County Health Department (Colorado, USA) as part of routine public health rabies surveillance during November 2018-July 2019 throughout Larimer County. Skunk carcasses were submitted to the Colorado State University Diagnostic Laboratory for rabies diagnosis using the direct fluorescent antibody test on the brainstem at the level on the pons and cerebellum. Multiple additional tissues were opportunistically collected from skunk carcasses and fixed in 10% neutral-buffered formalin, including brain, trigeminal ganglion, mandibular and parotid salivary glands, eyes, tongue, lip (including vibrissa), ear pinna, and uterus and fetus if pregnant. Fixed tissues were trimmed for histology, stained with H&E, and immunolabeled for detection of the rabies virus (RV) antigen. We detected RV immunopositive cells in multiple sections of brain, oral and nasal cavities, skin, and eyes as well as in the placenta and skin of fetuses from rabid skunks, suggesting the potential for transplacental transmission. We detected RV in the nerves and ganglia of salivary glands before detection in the salivary parenchymal cells in rabid skunks. The serous demilunes of the mandibular salivary gland appeared to be the first parenchymal cells to be infected with RV. We detected minimal RV immunopositive cells in the serous adenomeres of the parotid salivary gland and the mucous adenomeres of salivary tissue of the tongue. The results suggest that swabs from the oral and nasal cavities and cornea and biopsies of the skin could be of value for enhanced rabies surveillance in cases where the animal's brain has been destroyed or is unavailable.

Marsupials of the genus Didelphis are important wild hosts of Trypanosoma cruzi, the causative agent of Chagas disease. They exhibit infection patterns influenced by parasite lineage, as well as distinctive immune responses. We herein assessed the infection status of white-eared opossums (Didelphis albiventris) in the Metropolitan Area of Mendoza (MAM), Argentina, by integrating parasitologic data and serologic responses to T. cruzi antigens (crude homogenates and recombinant proteins) with physiologic and ecologic parameters of the animals. We captured 33 opossums between 2018 and 2021. High infection rates were detected, with 64% (21/33) seropositive by homogenate-based ELISA and 48% (10/21) positivity by quantitative PCR (qPCR). Parasite loads ranged from <0.001 to 40.98 parasite-equivalents/mL, and infected animals were detected in both peri-urban and rural sites. Animals that were qPCR-positive, seronegative occurred exclusively in peri-urban areas, suggesting acute, active infections, whereas seropositive, qPCR-negative individuals generally exhibited good or regular body condition, consistent with chronic or controlled infections. Hierarchical clustering of the reactivity of seropositive animals to recombinant T. cruzi antigens (Ag1 and trypomastigote small surface antigen isoforms) enabled three distinct serologic profiles to be identified. These profiles were associated with different physiologic and ecologic features and were therefore probably caused by infection with different T. cruzi genotypes. Overall, these findings highlight the complex epidemiologic role of D. albiventris in T. cruzi transmission in the MAM and support antigen-specific serology as a useful tool to infer infection dynamics and parasite diversity in epidemiologic studies.

The Guadalupe fur seal (GFS; Arctocephalus townsendi) is susceptible to the ecologic impacts of anomalous ocean warming events, which have led to prey scarcity that, in turn, affects its feeding habits, nutritional condition, and survival at Guadalupe Island, Mexico. Concurrently, ocean warming has also caused increased outbreaks of zoonotic diseases in North Pacific pinnipeds. This study assessed the exposure to zoonotic disease agents (Leptospira spp., Sarcocystis neurona, and Toxoplasma gondii) in GFS on Guadalupe Island (2016, 2017, and 2020), during a period of persistent ocean warming and unusual strandings in Mexico and the USA. Blood samples were collected from 129 GFS (82 females and 47 males) at Guadalupe Island. All tested GFS were seronegative for Leptospira spp. and S. neurona, whereas 17/129 (13%) tested seropositive for T. gondii, predominantly pups (1 yr) of both sexes. Although T. gondii was only detected in a relatively small proportion of GFS at Guadalupe Island, the parasite is frequently reported in pinniped populations inhabiting coastal ecosystems worldwide. Currently, the GFS population is increasing, which may promote range expansion and increase interaction with other marine mammals that may carry zoonotic pathogens along the coastal ecosystems of the northeastern Pacific Ocean. Only GFS pups were seropositive for T. gondii, which may reflect a passive transfer of maternal antibodies during lactation. However, the low prevalence observed may also indicate limited environmental exposure or other ecologic factors. As on other islands, exotic invasive species are reported in Guadalupe Island, which cannot be discounted as a possible source of exposure of GFS to pathogens and parasites such as T. gondii.

Blood sampling is a critical component of wildlife research, particularly in studies of wildlife diseases. However, limited information exists on venipuncture sites for Chilean wild rodent species, such as the olive-colored akodont (Abrothrix olivaceus), Darwin's pericote (Phyllotis darwini), and degu (Octodon degus). Here, we describe field-tested venipuncture sites that allowed the collection of measurable blood volumes suitable for molecular detection of Trypanosoma cruzi in these species, based on fieldwork conducted in Chile's semiarid Mediterranean ecosystem. We provide anatomical illustrations and practical recommendations for non-lethal blood collection. This short communication aims to assist researchers in obtaining reliable blood samples while ensuring animal welfare and minimizing stress.

Mycobacterium avium subspecies paratuberculosis (MAP) infection (Johne's disease; paratuberculosis) is a bacterial disease primarily of domestic ruminants that causes weight loss, diarrhea, and mortality. It has been documented in North American wild ruminants previously (e.g., Rocky Mountain bighorn sheep [Ovis canadensis canadensis], Key deer [Odocoileus virginianus clavium], Rocky Mountain goat [Oreamnos americanus], tule elk [Cervus canadensis nannodes], and white-tailed deer [Odocoileus virginianus]); however, the prevalence and implications of this disease in free-ranging populations are generally unknown. In May 2021, an adult female bighorn sheep carcass was retrieved from the Encampment River Herd in southeastern Wyoming, USA. Gross and histologic examinations were performed. Lesions consistent with MAP infection were identified and included emaciation, unformed feces with perineal staining (evidence of diarrhea), chronic inflammation of the small intestine, and inflammation of the internal abdominal lymph nodes. Additionally, MAP was confirmed in a fecal sample by using PCR. A subsequent opportunistic noninvasive field investigation was initiated to ascertain MAP establishment and possible prevalence in the herd from June to August 2021. In the 73 fecal samples collected, MAP was not detected. This work encourages and guides future surveillance using noninvasive methods and highlights the need for more research into the areas of wildlife-livestock interface diseases.

Landscapes of the Anthropocene, increasingly shaped by deforestation, climate change, and productive activities, are key settings for pathogen emergence and re-emergence. In this context, wildlife health surveillance is critical for early detection and risk mitigation. We describe the development, implementation, and operational outcomes of an integrated wildlife health surveillance system in protected areas of Argentina between 2022 and 2025, following its transition from marsh deer (Blastocerus dichotomus) mortality monitoring to a multispecies framework. The system integrated participatory, passive, and active surveillance modalities, with participatory surveillance functioning as a cross-cutting component supporting both mortality event detection and field implementation. The participatory network involved 110 members and was strengthened through training, standardized protocols, and field-based collaboration. Passive surveillance documented 205 records of wildlife morbidity and mortality, structured through three complementary reporting channels: surveillance network reports, wildlife rescue centers, and research team detections. Active surveillance focused on Ehrlichia chaffeensis and Theileria cervi, combining standardized grid-based sampling with complementary sampling of domestic dogs and environmental matrices. Grid-based sampling integrated rodent trapping, tick dragging, and camera trapping within a unified spatial design, yielding 471 rodents, 696 questing ticks, and records of 14 mammal species. Additional components included 185 domestic dogs sampled in one peri-protected area and 263 environmental samples across multiple matrices. System performance varied across implementation contexts, shaped by territorial presence of personnel, local infrastructure, and continuity of field activities. Integration of surveillance modalities enabled coordinated workflows, strengthened interinstitutional collaboration, and improved sample use efficiency across concurrent research efforts, expanding detection capacity, enhancing sample quality, and reducing redundant animal handling. The diagnostic network incorporated 12 institutions supporting coordinated sample processing. This study provides an operational framework for integrated wildlife health surveillance in resource-limited settings, highlighting the role of participatory approaches and the importance of institutional support, local capacity, and sustained engagement for long-term sustainability and consolidation of existing surveillance programs under a One Health perspective.

Dirofilaria striata is a filarioid nematode of domestic and wild felids. Differentiating this species from other filarioid nematodes is challenging due to the lack of comprehensive morphologic and molecular data. This short report provides concurrent molecular and morphologic data of microfilariae consistent with D. striata in a free-living Florida panther (Puma concolor coryi) from southwest Florida, USA. Also, we present evidence of a potential cross-reaction of D. striata on three different commercially available Dirofilaria immitis antigen tests.

Nephrolithiasis in cetaceans has been documented primarily in managed populations of bottlenose dolphins (Tursiops truncatus) with few described cases of nephroliths and vaginoliths in free-ranging cetacean species. Between 2006 and 2023, renal and/or vaginal calculi were identified on necropsy in 16 cetaceans that stranded on Cape Cod and in southeastern Massachusetts, USA. All vaginoliths (n=4) and most nephroliths were observed in short-beaked common dolphins (Delphinus delphis; n=9). Singular nephrolithiasis cases were also identified in a harbor porpoise (Phocoena phocoena), fin whale (Balaenoptera physalus), humpback whale (Megaptera novaeangliae), and long-finned pilot whale (Globicephala melas). Numbers of nephroliths in each animal ranged from 1 to >100 and nephrolith diameter ranged from 1 mm to 2.5 cm. Nephroliths were predominantly composed of: 100% ammonium urate in common dolphins (8/9 cases), 100% calcium phosphate carbonate in the fin and humpback whales, and 100% calcium oxalate dihydrate in the pilot whale; nephroliths were unavailable for analysis in the porpoise. Vaginoliths were predominantly composed of struvite but also contained lesser percentages of calcium carbonate and ammonium urate. None of the cases with antemortem blood analysis (n=7) had elevated renal parameters; however, two common dolphins had significant nephrolith-associated renal inflammation identified histologically, one of which also had bacterial pyelonephritis. Most nephroliths appeared to be incidental to the stranding; however, nephrolithiasis cases documented in common dolphins have increased over the past decade without significant change in necropsy protocols. No nephrolithiasis cases were documented in common dolphins 2006-16 (0/147), but starting in 2017, there was at least one documented case per year (9/103, 8.7%). To continue monitoring this potentially emerging trend, clinical and necropsy examinations of stranded cetaceans, especially in the western North Atlantic, should carefully evaluate for evidence of the condition, its potential clinical significance, and possible causes.

Nematodes in the genus Spirocerca, transmitted by dung beetles, infect both domestic dogs (Canis familiaris) and a multitude of wild carnivore species worldwide. Spirocerca infections in wild carnivores and their potential implications for conservation are not fully understood. This review aimed to analyze existing research on spirocercosis in wildlife and to highlight key differences between spirocercosis in wild and domestic carnivores. Spirocerca spp. have been detected in 35 wild host species in 31 countries across five continents. Typical pathologic signs of infection include aortic aneurysms, gastric and esophageal nodules, and aberrant migration within the thorax and abdomen. Complications seen in domestic dogs, such as vertebral spondylitis and hypertrophic osteopathy, have not been observed in wildlife. The reasons for these differences are not fully understood, but hypotheses include a relatively immature immune system in dogs, differences in diet, and evolved resistance to infection in wild hosts. Findings indicate that spirocercosis may not greatly impact healthy wild populations but could be devastating for critically endangered species. Future research should focus on screening for spirocercosis in wildlife after routine culling by using molecular methods to identify the species of Spirocerca nematodes instead of relying solely on morphologic characteristics.

The Vancouver Island marmot (VIM; Marmota vancouverensis) is a critically endangered sciurid endemic to the subalpine meadows of Vancouver Island, British Columbia, Canada. In response to population declines in the 1980s and 1990s, an intensive conservation breeding and reintroduction program was initiated in 1997. This recovery effort has generated significant health-related data from the captive, captive-release, and wild VIM populations, including results from 153 ex situ and 820 in situ mortalities. There were important differences in surveillance between captive and free-ranging populations (captive release and wild). Ex situ marmots exhibited greater longevity, were monitored with greater intensity, were carefully managed during hibernation, and were safeguarded against predation. These factors facilitated prompt recognition, recovery, and evaluation of mortalities. Cardiomyopathy and neoplasia represented the most significant causes of mortality in captives but were not observed in their in situ counterparts, possibly due to reduced longevity, dissimilar risk patterns, or limited opportunities to evaluate intact carcasses. Intact carcasses of free-ranging marmots were mainly recovered in spring and resulted from hibernation-related, postemergent emaciation. Mortalities of free-ranging VIMs often presented as incomplete remains or were inaccessible in burrows, meaning they were evaluated according to on-site field observations. Investigations indicated that the first wild hibernation was a time of substantial mortality for marmots released from captivity. However, captive releases that survived their first winter displayed a low incidence of hibernation mortality in subsequent winters, a success rate similar to that of their wild-born counterparts. Predators, particularly cougars (Puma concolor), represented the most consequential cause of mortality for both captive-release and wild marmots. No specific infectious agents were identified as presenting a generalized threat to in situ or ex situ populations. Chronic obesity in captives, reduced hibernation survival of first-year captive releases, and pronounced, seasonal predation of free-ranging marmots appear to represent important factors influencing the health and recovery of this critically endangered species.

The Humboldt Penguin (Spheniscus humboldti) is an IUCN Vulnerable species endemic to the Humboldt Current on the western coast of South America. Infectious disease is an inadequately understood potential threat to this species. To assess for the occurrence and prevalence of potential pathogens, conventional and quantitative PCR assays were conducted for 23 viral and bacterial targets in cloacal and tracheal swabs from adult penguins (n=224) sampled from 2009 to 2018 in a Peruvian breeding colony. Adenoviruses, circoviruses, herpesviruses, and Mycoplasma spp. were detected. Adenoviruses were detected at low prevalence (1%). Two circoviruses were detected: one circovirus with high homology to porcine circovirus 2 (overall positivity 14% of sampled individuals) and another apparently novel circovirus (12%). Spheniscid alphaherpesvirus 1 (overall positivity 3%) and penguin herpesvirus 1 (1%) were detected at low prevalence. Positivity to Mycoplasma gallisepticum was 26%. Various other Mycoplasma spp. were also detected (overall positivity 10%). Gallid herpesvirus 1, psittacine herpesvirus 1, psittacine circovirus, avian polyomavirus 1, avipoxviruses, coronaviruses, orthoreoviruses, Chlamydophila pneumoniae, Chlamydophila psittaci, Mycoplasma synoviae, and Salmonella enterica (serovars Typhimurium, Enteriditis, Pullorum, and Gallisepticum) were not detected. This study contributes to existing knowledge of the prevalence of potential pathogens in Humboldt Penguins. Further work is needed to characterize the epidemiology and health significance of detected pathogens, particularly circoviruses and Mycoplasma species.

Parasitic infections in wildlife represent a significant concern for animal health, ecosystem stability, and public health due to their zoonotic potential. This study aimed to determine the prevalence and taxonomic diversity of gastrointestinal parasites in wild carnivore admitted to a wildlife rescue and rehabilitation center in northeastern Türkiye, a transboundary region within the Caucasus biodiversity hotspot. A total of 57 wild carnivores belonging to six species and originating from five provinces of Türkiye were examined using standard qualitative coproparasitologic methods, including flotation, sedimentation, and modified acid-fast staining techniques. Prevalence rates were calculated descriptively with exact 95% confidence intervals. Overall, 35% (20/57) of the carnivores were positive for at least one gastrointestinal parasite. Eight parasite taxa were identified, including nematodes (Toxascaris leonina, Toxocara canis, Trichuris spp., Capillaria spp., Strongyloides sp., and Ascarid-type eggs), trematodes (Alaria spp.), and cestodes (Taeniid-type eggs). Toxascaris leonina was the most prevalent species (14%), predominantly detected in red foxes (Vulpes vulpes). Several detected taxa, including Alaria spp., Taenia spp., Toxocara canis, and other helminths, are of recognized veterinary and zoonotic importance. This study provides baseline epidemiological data on gastrointestinal parasites in wildlife admitted to a rehabilitation center in northeastern Türkiye and highlights the potential role of wild carnivores as reservoirs contributing to environmental contamination and parasite transmission at the wildlife-domestic animal-human interface. These findings support the need for integrated One Health-based surveillance strategies in transboundary ecosystems.

Feline panleukopenia virus (FPV) was confirmed by PCR in four free-ranging Bengal tiger cubs (Panthera tigris tigris) from South India. Phylogenetic placement of VP2 gene sequences showed clustering with domestic cat and wild carnivore isolates from the South Indian landscape, highlighting the potential for pathogen spillover at domestic-wildlife interfaces.