Causes of morbidity and mortality in wild cottontail rabbits in the eastern United States, 2013-2022.

Interest in causes of mortality of free-ranging, native North American lagomorphs has grown with the emergence of rabbit hemorrhagic disease virus 2 (RHDV2). Over the years 2013-2022, the Southeastern Cooperative Wildlife Disease Study received 119 Sylvilagus spp. case submissions from the central and eastern United States, comprising 147 rabbits. Most (86%) of these submissions occurred after detecting RHDV2 in the United States in 2020. Laboratory data from these rabbits were retrospectively evaluated for major causes, contributors to mortality, and pathogen detections. Gross and histologic examination was performed for 112 rabbits. Common primary causes of death included trauma (n = 49), bacterial disease (n = 31), emaciation (n = 6), and parasitism (n = 6). Among the 32 rabbits with bacterial disease, 12 were diagnosed with tularemia and 7 with pasteurellosis. Rabbits with pasteurellosis had disseminated abscessation, septicemia, and/or polyserositis. Less commonly, cutaneous fibroma (n = 2), notoedric mange (n = 2), encephalitozoonosis (n = 2), neoplasia (round-cell sarcoma; n = 1), and congenital abnormalities (n = 1) were diagnosed. RHDV2 was not detected in 123 rabbits tested. Although RHDV2 has not been detected in wild lagomorphs in the eastern United States, detections in domestic rabbits from the region emphasize the need for continued surveillance. Furthermore, continued surveillance for Francisella tularensis informs public health risk. Overall, increased knowledge of Sylvilagus spp. health furthers our understanding of diseases affecting these important prey and game species.

Health Assessment of Adult Male Eastern Wild Turkeys (Meleagris gallopavo silvestris) from Western Kentucky, USA.

Wild turkeys (Meleagris gallopavo) are an important game species throughout the geographic range. Populations throughout multiple regions of the US have been declining, including in Kentucky, US, raising concerns among managers and resource users. To better understand the overall population health, we performed postmortem examinations and targeted pathogen, mineral, and toxicant testing on 36 adult male, apparently healthy, wild turkeys that were hunter harvested in western Kentucky during April 2018. We found that birds were in fair to good nutritional condition with no significant gross or microscopic lesions. Ticks (Amblyomma spp.) and lice (three species) were present on 94 and 31% of birds, respectively. We commonly detected intestinal nematodes and cestodes and found coccidian oocysts in 39% and capillarid eggs in 6% of birds. The prevalences of lymphoproliferative disease virus and reticuloendotheliosis virus were 39 and 11%, respectively. Spleen samples tested with PCR were positive for Borrelia burgdorferi, Haemoproteus sp., and Leucocytozoon sp. in 11, 83, and 3%, respectively. Based on a subjective histologic assessment of testis tissues, most birds had widespread and abundant sperm present. Mineral analysis and broad toxicant screening on liver samples from 32 turkeys were unremarkable. Further work is needed to assess potential population risk factors and to determine individual- and population-level impacts of pathogens on adults and poults.

Metagenomics for Pathogen Detection During a Mass Mortality Event in Songbirds.

Mass mortality events in wildlife can be indications of an emerging infectious disease. During the spring and summer of 2021, hundreds of dead passerines were reported across the eastern US. Birds exhibited a range of clinical signs including swollen conjunctiva, ocular discharge, ataxia, and nystagmus. As part of the diagnostic investigation, high-throughput metagenomic next-generation sequencing was performed across three molecular laboratories on samples from affected birds. Many potentially pathogenic microbes were detected, with bacteria forming the largest proportion; however, no singular agent was consistently identified, with many of the detected microbes also found in unaffected (control) birds and thus considered to be subclinical infections. Congruent results across laboratories have helped drive further investigation into alternative causes, including environmental contaminants and nutritional deficiencies. This work highlights the utility of metagenomic approaches in investigations of emerging diseases and provides a framework for future wildlife mortality events.

Surveillance for Selected Pathogens and Parasites of Northern Bobwhite (Colinus virginianus) from Western Oklahoma, USA, 2018-20.

The Northern Bobwhite (Colinus virginianus) has been undergoing a range-wide population decline. Potential causes for declines across its historic range have been investigated for decades and include habitat loss and fragmentation and a variety of parasitic and infectious diseases. Although there have been studies on bobwhite ecology in Oklahoma, USA, relatively little is known about parasites and pathogens in the region. We evaluated the health of free-ranging bobwhites from nine sites in western Oklahoma. From 2018 to 2020, 206 bobwhites were evaluated for gross and microscopic lesions and tested for selected pathogens. In general, bobwhites were in good nutritional condition with ample muscle mass and fat stores. No significant gross lesions were observed in any bobwhite and no significant histologic lesions were detected in a subset. There was no evidence of infection with or exposure to reticuloendotheliosis virus, West Nile virus, respiratory Mycoplasmataceae species, Pasteurella multocida, intestinal Eimeria spp., or oral Trichomonas spp. Several pathogens of potential concern were detected, including avian adenovirus (8.6%), Toxoplasma gondii (2.3%), and haemosporidians (a Haemoproteus sp. (1.5%), Leucocytozoon schoutedeni (1.5%), and Plasmodium homopolare haplotype 2 [lineage LAIRI01; 3.6%]). Physaloptera sp. (12%) and Sarcocystis sp. (1%) were detected in the breast muscle. Low intraspecific genetic diversity was noted for Physaloptera sp., and sequences were most similar to Physaloptera sequences from bobwhites and grasshoppers (Orthoptera) in Texas. Low intensities of chewing lice, chiggers, and ticks were observed. A subset of bobwhites had evidence of exposure to selected toxicants and heavy metals; a small number had low levels of iron, manganese, zinc, molybdenum, and copper, which were not considered diagnostically relevant. In general, bobwhites from western Oklahoma appeared to be in good health with a low diversity of pathogens detected, but future work is needed to understand potentially changing disease risks for this population.

Experimental infection of domestic turkeys with lymphoproliferative disease virus of North American origin.

Lymphoproliferative disease virus (LPDV) was first documented in wild turkeys in North America in 2009. LPDV infection is often subclinical but can manifest as lymphoid proliferation or round cell neoplasia. Despite high prevalence across many sampled areas corresponding to declining populations of wild turkeys, knowledge regarding LPDV pathogenesis, risk factors for disease development, and associated impacts on population dynamics are unknown. To understand transmission, viral shedding, and tissue tropism, we inoculated 21 domestic turkeys via the oral cavity, crop, nasal cavity, subcutis, or coelomic cavity. For 12 weeks, oropharyngeal swabs, cloacal swabs, and whole blood were collected weekly. At 1 week postinoculation, 3 turkeys (3/21; 14%) had detectable LPDV proviral DNA in blood by polymerase chain reaction, and 10 developed DNAemia (50%; 10/20) by 12 weeks. LPDV proviral DNA was intermittently detected in oropharyngeal and cloacal swabs. Splenomegaly was the most consistent gross finding in DNAemic birds (8/11; 73%). Lymphoid hyperplasia in the spleen was the most significant microscopic finding (9/11; 82%). Three turkeys (3/11; 27%) developed round cell neoplasia characterized by sheets of pleomorphic, round to polygonal cells in the adrenal gland, bone marrow, skin, small intestine, and/or spleen. LPDV was detected in the spleen and bone marrow from all turkeys with DNAemia and all neoplasms. Our study establishes that infection and disease with North American LPDV from wild turkeys can be experimentally reproduced in domestic turkeys, laying the groundwork for future investigations into LPDV pathogenesis, development of diagnostic techniques, and understanding the impacts of LPDV on wild turkey populations.

Lymphoproliferative Disease Virus and Reticuloendotheliosis Virus Detection and Disease in Wild Turkeys (Meleagris gallopavo).

Lymphoproliferative disease virus (LPDV) and reticuloendotheliosis virus (REV) are oncogenic retroviruses that can cause disease in wild and domestic fowl. Lymphoproliferative disease virus infections are common and widespread in Wild Turkeys (Meleagris gallopavo) in the US and east-central Canada, while REV has been detected worldwide in numerous avian host species. We tested tissues (spleen, liver, and/or bone marrow, plus neoplastic tissue, if present) from 172 Wild Turkeys that underwent necropsy from December 2018 through October 2021 for both viruses using PCR. We evaluated demographic, geographic, temporal, and seasonal data by chi-square test of independence and logistic regression for turkeys infected with LPDV and/or REV. At least one of these retroviruses was detected in 80.8% (139/172) of Wild Turkeys from 15 US states, with significantly more turkeys being positive for LPDV (72.1%, 124/172) versus REV (43.6%, 75/172; P<0.001). Both viruses (coinfections) were detected in 34.9% (60/172) of turkeys. Among LPDV-infected turkeys (including coinfections), bone marrow had the highest detection rate (38/58, 65.5%), significantly higher than spleen (30/58, 51.7%) and liver (20/58, 34.5%; P<0.001). In REV-infected turkeys, bone marrow had the highest detection rate (24/58, 41.4%). All three tissues (spleen, liver, bone marrow) concurrently tested positive in most (15/25, 60%) REV-infected turkeys. These results suggest LPDV tissue tropism for bone marrow, whereas REV may have broader tissue tropism. Histopathology consistent with lymphoid proliferation and/or neoplasia characteristic of lymphoproliferative disease was evident in 29/172 (16.9%) turkeys assessed, including two REV-only-infected turkeys. Season was significantly associated with LPDV prevalence (highest in winter); year and season were both significantly associated with REV prevalence (highest in 2020 and winter). These data contribute to optimizing diagnostic strategies that may aid in pathogen monitoring and improve detections to increase our understanding of the potential impacts of these viruses on Wild Turkey populations.

Health impacts of gastrointestinal and ocular parasites in northern bobwhite (Colinus virginianus) in western Oklahoma, USA.

The northern bobwhite (Colinus virginianus) is a popular upland game bird that is suffering from severe and ongoing population decline. In this study, we investigated the potential health impacts of gastrointestinal and periorbital parasites in bobwhite in western Oklahoma, USA. A sample of 206 bobwhites from 2018 to 2020 indicated a low prevalence and diversity of parasites. However, at least one gastrointestinal or ocular parasite species was detected in 112 bobwhite (54.4%). A total of three gastrointestinal parasite species were detected, including Aulonocephalus pennula (54% prevalence, mean intensity 71.6 ± 99.8), Raillietina spp. (7%, 4.2 ± 1.9), and a single immature Mediorhynchus sp. acanthocephalan (0.5%). Burdens of A. pennula infections were negatively associated with fat stores in their bobwhite host. Low intensities (range 1-10, mean 3.9 ± 2.9) of eyeworms (Oxyspirura petrowi) were observed in 12.6% (26/206) of bobwhite sampled and were not associated with fat stores. No significant histologic lesions were associated with O. petrowi worms in ocular and surrounding tissues of 68 quail eyes examined, of which 26 (38%) were positive for eyeworms. Overall, the prevalence and intensity of parasites in bobwhite in Oklahoma were lower than in previous studies in Texas in similar physiographic regions. However, continued studies on the impacts of these parasites on quail health are needed as environmental and climate changes could alter the ecology and significance of these parasites.

Human Salmonellosis Outbreak Linked to Salmonella Typhimurium Epidemic in Wild Songbirds, United States, 2020-2021.

Salmonella infection causes epidemic death in wild songbirds, with potential to spread to humans. In February 2021, public health officials in Oregon and Washington, USA, isolated a strain of Salmonella enterica serovar Typhimurium from humans and a wild songbird. Investigation by public health partners ultimately identified 30 illnesses in 12 states linked to an epidemic of Salmonella Typhimurium in songbirds. We report a multistate outbreak of human salmonellosis associated with songbirds, resulting from direct handling of sick and dead birds or indirect contact with contaminated birdfeeders. Companion animals might have contributed to the spread of Salmonella between songbirds and patients; the outbreak strain was detected in 1 ill dog, and a cat became ill after contact with a wild bird. This outbreak highlights a One Health issue where actions like regular cleaning of birdfeeders might reduce the health risk to wildlife, companion animals, and humans.

Using Opportunistic Samples to Monitor West Nile Virus Infection Status in Greater Sage-grouse (Centrocercus urophasianus) in Wyoming, USA (2020-22).

The frequency of arthropod-borne viral disease in naïve hosts is subject to change based on complex interactions among vector, host, virus, and external factors (e.g., climate). Thus, continual monitoring for both disease susceptibility and host infection dynamics is needed, especially for viruses that have proven detrimental to the health of wildlife hosts of conservation concern. The Greater Sage-grouse (Centrocercus urophasianus) is a gamebird of ecological and economic importance in the western United States for which population declines have led to a Near Threatened conservation status. Although these declines have mainly been attributed to habitat loss, West Nile virus (WNV) also poses a threat, with regional transmission potentially fueled by anthropogenic landscape alterations that may facilitate mosquito breeding. With limited WNV monitoring in Greater Sage-grouse after recognition of high susceptibility to mortality early after its initial detection in the western United States, the potential long-term impacts of WNV on this species are poorly understood. We used the plaque reduction neutralization test of filter paper strip-eluted sera to assess for anti-WNV antibodies, indicating prior infection, in opportunistically collected samples. From 2020 to 2022, 85 Greater Sage-grouse in Wyoming were sampled; none had anti-WNV antibodies. This result corroborates findings of previous studies documenting low seroprevalence. With the tenuous conservation status of the species, all potential population health risks should be considered in future management strategies, especially in the face of changing climate and landscapes.

Abundance and diversity of Culicoides Latreille (Diptera: Ceratopogonidae) in southern Ontario, Canada.

BACKGROUND: Culicoides Latreille (Diptera: Ceratopogonidae) is a genus of hematophagous midges feeding on various vertebrate hosts and serving as a vector for numerous pathogens important to livestock and wildlife health. North American pathogens include bluetongue (BT) and epizootic hemorrhagic disease (EHD) viruses. Little is known about Culicoides spp. distribution and abundance and species composition in Ontario, Canada, despite bordering numerous U.S. states with documented Culicoides spp. and BT and EHD virus activity. We sought to characterize Culicoides spp. distribution and abundance and to investigate whether select meteorological and ecological risk factors influenced the abundance of Culicoides biguttatus, C. stellifer, and the subgenus Avaritia trapped throughout southern Ontario. METHODS: From June to October of 2017 to 2018, CDC-type LED light suction traps were placed on twelve livestock-associated sites across southern Ontario. Culicoides spp. collected were morphologically identified to the species level when possible. Associations were examined using negative binomial regression among C. biguttatus, C. stellifer, and subgenus Avaritia abundance, and select factors: ambient temperature, rainfall, primary livestock species, latitude, and habitat type. RESULTS: In total, 33,905 Culicoides spp. midges were collected, encompassing 14 species from seven subgenera and one species group. Culicoides sonorensis was collected from three sites during both years. Within Ontario, the northern trapping locations had a pattern of seasonal peak abundance in August (2017) and July (2018), and the southern locations had abundance peaks in June for both years. Culicoides biguttatus, C. stellifer, and subgenus Avaritia were significantly more abundant if ovine was the primary livestock species at trapping sites (compared to bovine). Culicoides stellifer and subgenus Avaritia were significantly more abundant at mid- to high-temperature ranges on trap days (i.e., 17.3-20.2 and 20.3-31.0 °C compared to 9.5-17.2 °C). Additionally, subgenus Avaritia were significantly more abundant if rainfall 4 weeks prior was between 2.7 and 20.1 mm compared to 0.0 mm and if rainfall 8 weeks prior was between 0.1 and 2.1 mm compared to 0.0 mm. CONCLUSIONS: Results from our study describe Culicoides spp. distribution in southern Ontario, the potential for spread and maintenance of EHD and BT viruses, and concurrent health risks to livestock and wildlife in southern Ontario in reference to certain meteorological and ecological risk factors. We identified that Culicoides spp. are diverse in this province, and appear to be distinctly distributed spatially and temporally. The livestock species present, temperature, and rainfall appear to have an impact on the abundance of C. biguttatus, C. stellifer, and subgenus Avaritia trapped. These findings could help inform targeted surveillance, control measures, and the development of management guides for Culicoides spp. and EHD and BT viruses in southern Ontario, Canada.

Storage time and temperature of filter paper strips affect anti-West Nile virus antibody detection in 2 galliform species.

The effects of filter paper strip (FPS) storage time and temperature on antibody detection are poorly understood despite widespread use in wildlife research. We collected sera and FPSs from 23 wild turkeys (Meleagris gallopavo) and 20 northern bobwhites (Colinus virginianus) experimentally infected with West Nile virus (WNV) to compare FPS storage methods with WNV plaque reduction neutralization test (PRNT) sensitivity. FPS storage methods included: immediate elution after drying, and storage at -20°C for 3 mo, -20°C for 6 mo, room temperature (RT) for 3 mo, and RT for 6 mo prior to elution. FPS eluates and sera were co-titrated to determine endpoint antibody titers, which were compared between FPS sera eluted immediately and sera, and among FPS eluates that underwent different storage conditions. Antibody titers were ~4-fold less in FPS sera eluted immediately versus sera, and dropped more frequently below PRNT detection threshold in northern bobwhites, which had ~10-fold lower serum antibody titers than wild turkeys. Antibody titers were lower in FPS samples stored at RT and for 6 mo. WNV serologic surveys may result in falsely low seroprevalence estimates if FPSs are stored at RT for ≥ 3 mo before elution.

Congenital Vertebral Malformation in a Neonatal Elk (Cervus canadensis) in Kentucky, USA.

We captured a <1-d-old male elk calf (Cervus canadensis) with a shortened neck. Postmortem examination revealed trauma, meconium aspiration syndrome, and cervical vertebral malformation (partial fusion and narrowed disc spaces). This observation is novel in a wild elk calf, although the gross lesions resembled complex vertebral malformation in neonatal cattle.

Bald eagle mortality and nest failure due to clade 2.3.4.4 highly pathogenic H5N1 influenza a virus.

The bald eagle (Haliaeetus leucocephalus) is a culturally and ecologically vital species in North America that embodies conservation success but continues to face threats that include emerging pathogens. The introduction of A/goose/Guangdong/1/1996 lineage highly pathogenic (HP) clade 2.3.4.4b H5N1 influenza A virus (IAV) in North America in late 2021 resulted in high rates of mortality among bald eagles. Here we show an alarming rate of bald eagle nest failure and mortality attributed to HP IAV. We documented fatal, systemic HP IAV infection in breeding adult and nestling bald eagles along the southeastern U.S. coast. Concurrently, annual bald eagle nest surveys in Georgia and Florida revealed a precipitous drop in success in coastal counties compared with previous years, portending negative impacts on population recruitment. As an apex predator and efficient scavenger, it is likely that bald eagles become infected through consumption of infected waterfowl. These results and similar reports of raptor mortality in Europe, Asia, and Africa, indicate a clear threat to raptor health. The possible long-term persistence of HP H5N1 IAV in North America poses an impending threat to bald eagle populations not only related to direct mortality but also decreased recruitment and warrants continued efforts to understand these potential impacts.

Comparison of Pathology and Immunohistochemistry in Natural and Experimental West Nile Virus Infections in Ruffed Grouse (Bonasa umbellus).

Ruffed Grouse (Bonasa umbellus) populations have declined in much of the eastern US in recent decades. Research suggests that West Nile virus (WNV) contributed to these declines, based on decreasing population indices temporally correlated to WNV introduction into North America, high morbidity and mortality in experimentally infected Ruffed Grouse, and relatively low statewide seroprevalence concurrent with high WNV vector indices. We describe lesions and relevant diagnostic findings in six, free-ranging Ruffed Grouse that directly or indirectly died of natural WNV infection and compare results to experimentally infected Ruffed Grouse. All naturally infected grouse were found moribund or dead from August to December 2015-18 in the northeastern US; 4/6 grouse were subadults. Necropsy, histopathology, immunohistochemistry, and/or ancillary tests contributed to the diagnosis of WNV-associated disease in all cases. The most common lesions in naturally infected grouse were myocardial inflammation, degeneration, and/or necrosis, consistent with lesions in experimentally infected grouse. Evidence of trauma in 6/6 naturally infected grouse suggests the possibility of WNV-associated morbidity as a predisposing factor. Diagnostic findings in 3/6 naturally infected grouse were consistent with experimentally infected grouse with severe disease 7-8 d postinoculation; the remaining naturally infected birds had similar findings to experimentally infected subclinical grouse. Our results further support the notion that WNV contributes to mortality of free-ranging Ruffed Grouse and may be used to improve surveillance strategies and population-level management approaches.

Susceptibility of wild turkeys (Meleagris gallopavo) to experimental West Nile virus infection.

Since the introduction of West Nile virus (WNV) to North America in 1999, WNV is estimated to have contributed to population-level declines in numerous avian species. However, the potential impacts of this virus on many free-ranging upland game bird species, including the wild turkey (Meleagris gallopavo), which is undergoing regional population declines, remain unknown. Herein, two age groups (∼5 to 6 weeks and ∼15 to 16 weeks post-hatch) of juvenile wild turkeys were subcutaneously inoculated with WNV, sampled daily from 1 to 7 days post-inoculation (dpi), and euthanized on 14 dpi. No clinical signs and minimal gross lesions were attributable to WNV infection. Peak viraemia titres were similar between age groups (<101.7 to 104.6 plaque-forming units [PFU]/ml), but the duration of viraemia was longer in the old group (3-4 days) than in the young group (0-3 days). Intermittent oral and/or cloacal viral shedding from 2 to 7 dpi was detected in both age groups. No infectious virus was detected in the heart, brain, kidney, skeletal muscle, spleen, and feathers from WNV-inoculated turkeys euthanized on 14 dpi. All WNV-inoculated birds seroconverted by 14 dpi, as well as two co-housed sham-inoculated birds. The most consistent microscopic lesions among all WNV-inoculated birds were mild lymphoplasmacytic myocarditis and encephalitis. Minimal immunohistochemical labelling was detected in tissues in addition to scant macrophages within the blood, spleen, and bone marrow. These data suggest WNV is unlikely to pose a significant risk to wild turkey populations, although the possibility remains that WNV may indirectly decrease fitness or predispose wild turkeys to other health stressors.RESEARCH HIGHLIGHTS Clinical disease was not observed in wild turkeys experimentally infected with WNV.Pathology attributed to WNV was mild and included brain and heart inflammation.Viraemias suggest WNV-infected wild turkeys do not play a role in WNV transmission.No age-associated differences in WNV clinical disease or pathology were observed.

Notoedric mange (Notoedres centrifera) in two species of free-ranging rabbits from Florida, USA.

Mange is a contagious skin disease caused by different mite species affecting numerous domestic and wild animals, worldwide. This report details notoedric mange in an eastern cottontail (Sylvilagus floridanus) and in a marsh rabbit (Sylvilagus palustris) from Florida, USA. Clinical examination revealed similar gross lesions including poor nutritional condition, multifocal alopecia and hyperkeratosis. Skin scrapings from both rabbits revealed numerous subcutaneous mites identified as Notoedres centrifera, a species previously only associated with rodents, primarily squirrels. Mites from both rabbits were identified based on morphology and confirmed by sequencing the internal transcribed spacer-2 (ITS-2) region. These cases emphasize the need for continued surveillance and accurate diagnostic evaluation to determine the cause and characterization of the skin disease, while distinguishing it from other potential pathogens that may manifest similarly in rabbits, such as Notoedres cati, Sarcoptes scabiei or Psoroptes cuniculi.

An Investigation of the Cause of Wild Turkey Mortality in Mississippi.

Lymphoproliferative disease virus (LPDV) is an exogenous alpharetrovirus that sporadically causes fatal lymphoid neoplasia in affected turkeys. Previous studies of wild turkeys (Meleagridis gallopavo) in the United States have demonstrated geographically widespread LPDV infection and frequent coinfection with avian poxvirus (APV) and reticuloendotheliosis virus (REV). This study was conducted to better understand health risks to Mississippi wild turkeys, including the relative importance of LPDV, APV, and REV in contributing to mortality. Thirteen wild turkeys, which died naturally or were euthanized due to illness, were submitted to Mississippi State University's Poultry Research and Diagnostic Laboratory for postmortem examinations. Birds originated from nine counties across the state over the past 5 yr. Carcasses were submitted as fresh (nonfrozen) or frozen. At autopsy, 9 of 13 turkeys had severe, proliferative cutaneous lesions on the head and neck, with diphtheritic or proliferative oral and esophageal lesions. Samples were collected for molecular diagnostic testing (LPDV and REV PCR), histopathology, and bacterial culture and isolation. External and internal parasites were preserved in formalin for identification. APV (cutaneous and/or diphtheritic forms) was diagnosed in 9 of 13 birds by identification of pathognomonic histologic lesions (including intracytoplasmic inclusion bodies). Interestingly, all birds with APV were also REV PCR positive. Furthermore, eight turkeys were positive for LPDV, and LPDV was commonly associated with coinfections with APV and REV.

El virus de la enfermedad linfoproliferativa (LPDV) es un Alfaretrovirus exógeno que esporádicamente provoca una neoplasia linfoide mortal en los pavos afectados. Estudios previos de pavos salvajes (Meleagridis gallopavo) en los Estados Unidos han demostrado que la infección por la enfermedad linfoproliferativa está geográficamente extendida y es una coinfección frecuente con el virus de la viruela aviar (APV) y el virus de la reticuloendoteliosis (REV). Este estudio se realizó para comprender mejor los riesgos para la salud de los pavos salvajes de Mississippi, incluida la importancia relativa de enfermedad linfoproliferativa, el virus de la viruela aviar y el virus de la reticuloendoteliosis en la contribución a la mortalidad. Trece pavos salvajes, que murieron naturalmente o fueron sacrificados por enfermedad, fueron enviados al Laboratorio de Investigación y Diagnóstico Avícola de la Universidad Estatal de Mississippi para exámenes post-mortem. Las aves provenían de condados de todo el estado durante los últimos cinco años. Las canales se enviaron tanto frescas (no congeladas) como congeladas. A la necropsia, 9 de 13 pavos mostraron lesiones cutáneas proliferativas graves en la cabeza y el cuello, con lesiones orales y esofágicas diftéricas o proliferativas. Se recolectaron muestras para pruebas de diagnóstico molecular (LPDV y REV PCR), histopatología y cultivo y aislamiento bacterianos. Los parásitos externos e internos se conservaron en formalina para su identificación. Se diagnosticó viruela aviar (formas cutáneas y/o diftéricas) se diagnosticó en 9 de 13 aves mediante la identificación de lesiones histológicas patognomónicas (incluidos los cuerpos de inclusión intracitoplasmáticos). Curiosamente, todas las aves con viruela aviar también fueron positivas a la presencia del virus de la reticuloendoteliosis por PCR. Además, ocho pavos fueron positivos para el virus de la enfermedad linfoproliferativa, y se asoció comúnmente con coinfecciones con viruela aviar y con el virus de la reticuloendoteliosis.

Listeriosis with viral coinfections in 8 gray foxes, 8 wild turkeys, and 2 young cervids in the southeastern United States.

Listeria monocytogenes is a bacterium that can cause disease in many species, including humans, livestock, and wildlife. Increased interactions via shared habitats may promote pathogen transmission among these groups. Our objectives were to evaluate the Southeastern Cooperative Wildlife Disease Study diagnostic data to characterize and compare L. monocytogenes-induced lesions and comorbidities in gray foxes and wild turkeys, and to describe cases of listeriosis in 2 cervids. From 1991-2020, 8 gray foxes, 8 wild turkeys, a neonatal elk, and a white-tailed deer fawn from several eastern states in the United States were diagnosed with listeriosis. All 8 foxes had hepatitis and/or hepatic necrosis with intralesional gram-positive bacilli, and concurrent canine distemper virus (CDV) infection; 2 of the foxes had been vaccinated recently for CDV. L. monocytogenes was cultured from the liver (6 of 8) or lung (2 of 8) of foxes. Lesions in wild turkeys included hepatocellular necrosis (3 of 8), heterophilic hepatitis (1 of 8), heterophilic granulomas (1 of 8), intrasinusoidal gram-positive bacilli without hepatic lesions (1 of 8), granulomatous dermatitis (1 of 8), and/or granulomatous myocarditis (2 of 8). Lymphoproliferative disease viral DNA was detected in 5 of 6 turkeys tested; reticuloendotheliosis viral DNA was detected in 2 of 3 turkeys tested. Both cervids had systemic listeriosis, with L. monocytogenes isolated from liver. Immunohistochemistry for Listeria spp. on select cases revealed immunolabeling in affected organs. Listeriosis was thus established as a cause of morbidity and mortality in 3 wildlife species, which often suffered from concurrent infections and likely immunosuppression.

Distinctive Gross Presentation in Free-Ranging White-Tailed Deer (Odocoileus virginianus) with Rabies.

The white-tailed deer (Odocoileus virginianus) is a popular game species in North America and often lives in close proximity to humans and domestic animals. Deer with neurologic signs are of high interest to the general public and wildlife managers because of disease and safety concerns. Our aim was to describe diagnostic findings from free-ranging white-tailed deer diagnosed with rabies from across the eastern US from 2000 to 2021, with emphasis on gross lesions in the skin and soft tissue overlying the skull. We reviewed diagnostic reports of white-tailed deer cases submitted to the Southeastern Cooperative Wildlife Disease Study for those diagnosed with rabies from 2000 to 2021. Rabies virus infection was confirmed by immunohistochemistry or fluorescent antibody test of brain, or both. Nine adult deer from five states were diagnosed with rabies, including seven (78%) females and two (22%) males. Three (33%) deer were found dead, and six (67%) were humanely dispatched for abnormal behavior. Six deer heads were examined grossly and had lesions, including forehead or periorbital alopecia, cutaneous erythema, abrasions and ulcers, and subcutaneous edema. Histologic examination was performed for eight of nine cases, all of which had intraneuronal eosinophilic inclusion (Negri) bodies in cerebrum, cerebellum, or both. Most (6/8; 75%) had perivascular lymphoplasmacytic encephalitis. Rabies should be considered a differential diagnosis in deer with this pattern of head lesions, suggestive of head rubbing or head pressing.

Molecular characterization of Sarcocystis spp. as a cause of protozoal encephalitis in a free-ranging black bear.

A free-ranging juvenile male black bear (Ursus americanus), found dead in Alberta, Canada, had severe nonsuppurative encephalitis. Lesions in the brain were most severe in the gray matter of the cerebral cortex, and included perivascular cuffs of lymphocytes and plasma cells, areas of gliosis that disrupted the neuropil, and intralesional protozoan schizonts. The left hindlimb had suppurative myositis associated with Streptococcus halichoeri. Immunohistochemistry and molecular analyses (PCR and sequencing of 4 discriminatory loci: 18S rDNA, ITS-1 rDNA, cox1, rpoB) identified Sarcocystis canis or a very closely related Sarcocystis sp. in the affected muscle and brain tissues. The main lesion described in previously reported cases of fatal sarcocystosis in bears was necrotizing hepatitis. Fatal encephalitis associated with this parasite represents a novel presentation of sarcocystosis in bears. Sarcocystosis should be considered a differential diagnosis for nonsuppurative encephalitis in bears.