Simian homologues of human herpesviruses and implications for novel viral introduction to free-living mountain gorillas.

The endangered mountain gorilla (Gorilla beringei beringei) in Rwanda, Uganda, and the Democratic Republic of Congo is frequently in contact with humans through tourism, research activities, and illegal entry of people into protected gorilla habitat. Herpesviruses, which are ubiquitous in primates, have the potential to be shared in any setting where humans and gorillas share habitat. Based on serological findings and clinical observations of orofacial ulcerated lesions resembling herpetic lesions, an alpha-herpesvirus resembling human herpes simplex virus type 1 (HSV-1) has long been suspected to be present in human-habituated mountain gorillas in the wild. While the etiology of orofacial lesions in the wild has not been confirmed, HSV-1 has been suspected in captively-housed mountain gorillas and confirmed in a co-housed confiscated Grauer's gorilla (Gorilla beringei graueri). To better characterize herpesviruses infecting mountain gorillas and to determine the presence/absence of HSV-1 in the free-living population, we conducted a population-wide survey to test for the presence of orally shed herpesviruses. DNA was extracted from discarded chewed plants collected from 294 individuals from 26 groups, and samples were screened by polymerase chain reaction using pan-herpesvirus and HSV-1-specific assays. We found no evidence that human herpesviruses had infected free-ranging mountain gorillas. However, we found gorilla-specific homologs to human herpesviruses, including cytomegaloviruses (GbbCMV-1 and 2), a lymphocryptovirus (GbbLCV-1), and a new rhadinovirus (GbbRHV-1) with similar characteristics (i.e., timing of primary infection, shedding in multiple age groups, and potential modes of transmission) to their human counterparts, human cytomegalovirus, Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus, respectively.

Reproductive tract neoplasia in adult female Asian elephants (Elephas maximus).

Recent reports have highlighted a lower-than-expected prevalence of neoplasia in elephants and suggested mechanisms for cancer resistance. But despite infrequent reports in the literature, uterine neoplasia is common in managed Asian elephants (Elephas maximus). This study is an archival review of reproductive tract neoplasia in 80 adult female Asian elephant mortalities in managed care facilities in the United States from 1988 to 2019. Neoplasms occurred in 64/80 (80%) of cases. Most were in the uterus (63/64; 98%) with only a single case of ovarian neoplasia. Myometrial leiomyomas were present in 57/63 (90%) cases with uterine neoplasia. Uterine adenocarcinoma was present in 8/63 (13%) cases. Remaining cases included endometrial adenoma (2), focal carcinoma in situ in endometrial polyps (1), anaplastic carcinoma (1), endometrial hemangioma (1), primitive neuroectodermal tumor (PNET; 1), and angiosarcoma (1). One case with uterine adenocarcinoma had a separate pelvic mass histologically characterized as an anaplastic sarcoma. Distant metastases were documented in 5/8 (63%) cases of uterine adenocarcinoma, and in the uterine anaplastic carcinoma, PNET, and angiosarcoma. Four uterine adenocarcinomas and one carcinoma in situ were examined immunohistochemically for pan-cytokeratin, vimentin, and estrogen receptor. In all, neoplastic cells were pan-cytokeratin positive and vimentin negative, and in 2 cases were immunoreactive for estrogen receptor. Results show that female reproductive tract neoplasia, particularly of the uterus, is common in Asian elephants and is not limited to leiomyomas. Importantly, uterine neoplasms have the potential to impact fecundity and may represent obstacles to conservation in managed care.

Pathological lesions of the digestive tract in free-ranging mountain gorillas (Gorilla beringei beringei).

The finding of parasites and bacterial pathogens in mountain gorilla feces and oral lesions in gorilla skeletal remains has not been linked to pathological evidence of morbidity or mortality. In the current study, we conducted a retrospective study of digestive tracts including oral cavity, salivary glands, esophagus, stomach, intestines (gastrointestinal tract [GI]), liver, and pancreas of 60 free-ranging mountain gorillas from Uganda, Rwanda, and the Democratic Republic of Congo that died between 1985 and 2007. We reviewed clinical histories and gross pathology reports and examined histological sections. On histology, enteritis (58.6%), gastritis (37.3%), and colitis (29.3%) were the commonest lesions in the tracts. Enteritis and colitis were generally mild, and judged likely to have been subclinical. Gastritis was often chronic and proliferative or ulcerative, and associated with nematodiasis. A gastro-duodenal malignancy (carcinoid) was present in one animal. A number of incidental lesions were identified throughout the tract and cestodes and nematodes were frequently observed grossly and/or histologically. Pigmentation of teeth and tongue were a common finding, but periodontitis and dental attrition were less common than reported from past studies of skeletal remains. Despite observing numerous GI lesions and parasites in this study of deceased free-living mountain gorillas, we confirmed mortality attributable to gastroenteritis in just 8% (5/60) cases, which is less than that described in captive gorillas. Other deaths attributed to digestive tract lesions included cleft palate in an infant, periodontal disease causing systemic infection in an older adult and gastric cancer. Of all the parasitic infections observed, only hepatic capillariasis and gastric nematodiasis were significantly associated with lesions (hepatitis and gastritis, respectively). Understanding GI lesions in this endangered species is key in the management of morbidity associated with GI ailments.

Morbidity and mortality in infant mountain gorillas (Gorilla beringei beringei): A 46-year retrospective review.

Long-term studies of morbidity and mortality in free-ranging primates are scarce, but may have important implications for the conservation of extant populations. Infants comprise a particularly important age group, as variation in survival rates may have a strong influence on population dynamics. Since 1968, the Mountain Gorilla Veterinary Project (MGVP, Inc.) and government partners have conducted a comprehensive health monitoring and disease investigation program on mountain gorillas (Gorilla beringei beringei) in Rwanda, Uganda, and the Democratic Republic of the Congo. In an effort to better understand diseases in this species, we reviewed reliable field reports (n = 37), gross post-mortem (n = 66), and histopathology (n = 53) reports for 103 infants (less than 3.5 years) mountain gorillas in the Virunga Massif. Our aim was to conduct the first comprehensive analysis of causes of infant mortality and to correlate histological evidence with antemortem morbidity in infant mountain gorillas. Causes of morbidity and mortality were described, and compared by age, sex, and over time. Trauma was the most common cause of death in infants (56%), followed by respiratory infections and aspiration (13%). Gastrointestinal parasitism (33%), atypical lymphoid hyperplasia (suggestive of infectious disease) (31%), and hepatic capillariasis (25%) were the most significant causes of antemortem morbidity identified post-mortem. Identifying the causes of mortality and morbidity in infants of this critically endangered species will help to inform policy aimed at their protection and guide ante- and post-mortem health monitoring and clinical decision-making in the future.

Mountain gorilla lymphocryptovirus has Epstein-Barr virus-like epidemiology and pathology in infants.

Epstein-Barr virus (EBV) infects greater than 90% of humans, is recognized as a significant comorbidity with HIV/AIDS, and is an etiologic agent for some human cancers. The critically endangered mountain gorilla population was suspected of infection with an EBV-like virus based on serology and infant histopathology similar to pulmonary reactive lymphoid hyperplasia (PRLH), a condition associated with EBV in HIV-infected children. To further examine the presence of EBV or an EBV-like virus in mountain gorillas, we conducted the first population-wide survey of oral samples for an EBV-like virus in a nonhuman great ape. We discovered that mountain gorillas are widely infected (n = 143/332) with a specific strain of lymphocryptovirus 1 (GbbLCV-1). Fifty-two percent of infant mountain gorillas were orally shedding GbbLCV-1, suggesting primary infection during this stage of life, similar to what is seen in humans in less developed countries. We then identified GbbLCV-1 in post-mortem infant lung tissues demonstrating histopathological lesions consistent with PRLH, suggesting primary infection with GbbLCV-1 is associated with PRLH in infants. Together, our findings demonstrate that mountain gorilla's infection with GbbLCV-1 could provide valuable information for human disease in a natural great ape setting and have potential conservation implications in this critically endangered species.

Ectopic pregnancy with associated gestational choriocarcinoma in a California sea lion (Zalophus californianus).

A wild-born, captive-reared, 14 yr old, primiparous female California sea lion Zalophus californianus presented for anorexia of 14 d duration and abdominal distention. Routine complete blood cell count revealed leukocytosis with a neutrophilia, and serum chemistry revealed hypoalbumenemia and hyponatremia. Treatment with broad spectrum antibiotics and non-steroidal anti-inflammatories were started, but the animal continued to decline. Abdominal radiographs revealed a mature mineralized fetal skull and spine in the caudal abdomen and abdominal ultrasound revealed ascites but could not confirm the fetus. The patient was taken to surgery where a full term fetus was found outside of the uterus but within the fetal membranes, representing a secondary ectopic pregnancy. The patient passed away during surgery and was taken to necropsy. Gross necropsy revealed a diffuse peritonitis with yellow deposits over the serosal surfaces of the abdominal organs. The uterus appeared intact grossly and the ovaries appeared abnormal. The mesenteric, renal, and sub-lumbar nodes were enlarged and edematous. Histopathology revealed choriocarcinoma in the right uterine horn with evidence of chronic uterine rupture and protrusion of the placental tissue into the abdomen. The choriocarcinoma had metastasized locally as well as to the liver, spleen and lung. Choriocarcinoma is a highly malignant trophoblastic neoplasm that is rare in domestic animals. This case represents, to the authors' knowledge, the first report of gestational choriocarcinoma causing secondary ectopic pregnancy in a California sea lion and presents questions regarding pregnancy monitoring and management in a population of captive, minimally trained California sea lions.

Human herpes simplex virus type 1 in confiscated gorilla.

In 2007, we detected human herpes simplex virus type 1, which caused stomatitis, in a juvenile confiscated eastern lowland gorilla (Gorilla beringei graueri) that had a high degree of direct contact with human caretakers. Our findings confirm that pathogens can transfer between nonhuman primate hosts and humans.

Fatal hepatic tetratrichomoniasis in a juvenile Waldrapp ibis (Geronticus eremita).

Waldrapp ibis (Geronticus eremita) are a critically endangered species, and there are currently more birds in captivity than in the wild. A juvenile, male Waldrapp ibis housed in a mixed-species exhibit was found dead with no premonitory signs. Necropsy revealed extensive necrotizing hepatitis associated with numerous pleomorphic protozoa that were immunohistochemically reactive with antibodies raised against Tritrichomonas foetus, a parasite of cattle. Electron microscopy confirmed the organisms as members of family Trichomonadidae, and sequence analysis of the first ribosomal internal transcribed spacer region (ITS1), 5.8S ribosomal RNA, and ITS2 regions indicated high genetic similarity (96-97%) to members of the Tetratrichomonas gallinarum complex. The animal was born in captivity, and no introductions in this exhibit had occurred since 2009. Other Waldrapp ibis that had contact with the infected male were negative for flagellate infections by fecal examination, thus cross-species transmission is proposed as the source of infection. The host range of the T. gallinarum complex is very large and although the pathogenicity of its members, especially for wild birds, is controversial, these parasites should be considered as a possible cause of acute mortality in Waldrapp ibis. In addition, immunohistochemistry with T. foetus antibodies and molecular diagnostics may be useful tools for preventative veterinary care of endangered bird populations. A greater understanding of the ecology and pathogenesis of this pathogen may also be vital for screening subclinical captive populations and existing wild populations prior to reintroduction efforts.

Respiratory disease in mountain gorillas (Gorilla beringei beringei) in Rwanda, 1990-2010: outbreaks, clinical course, and medical management.

Between 1990 and 2010, 18 outbreaks of respiratory disease occurred in Rwanda's wild human-habituated mountain gorillas (Gorilla beringei beringei). An outbreak was defined as clinically observable respiratory illness involving at least one third of all the gorillas in a family group (> 30% morbidity) over the course of at least 7 days. Outbreaks lasted 2 wk to 4 mo and affected up to five different gorilla family groups, either concurrently or sequentially. An outbreak was considered over if no further clinical illness was observed in the same or another group for at least 1 mo. Clinical signs varied from nasal discharge, sneezing, and mild intermittent coughing (mild), to spasmodic coughing, lethargy, and partial anorexia (moderate), to dyspnea, tachypnea, respiratory distress, weakness, complete anorexia, and occasionally death (severe). Nearly every mountain gorilla group habituated for tourism or research in Rwanda experienced at least one outbreak, and they may be increasing in frequency. In the first 15 yr of the review period 1990-2005, there were nine outbreaks involving 16 gorilla groups; in the last 5 yr of the review period, 2006-2010, there were nine outbreaks involving 11 groups. Although most gorillas recovered without treatment, 41 veterinary procedures were required to medically manage 35 severely ill individuals. Given the rise of mountain gorilla ecotourism in Rwanda, the possibility that respiratory disease results from contact with infected humans is of great concern, and both the etiology and epidemiology of this problem are active areas of research. The observed clinical signs, response to antimicrobial therapy among the sickest individuals, and postmortem findings are most consistent with viral upper respiratory tract infections complicated in some cases by secondary bacterial infections. The current gorilla visitation rules have been designed to minimize the risk of disease transmission between humans and wild human-habituated great apes.

Squamous cell carcinoma of the anal sac in a spotted hyena (Crocuta crocuta).

A 25-yr-old spayed female spotted hyena (Crocuta crocuta) developed intermittent right pelvic limb lameness that persisted following conservative medical therapy. No obvious musculoskeletal lesions were noted on initial physical exam; however, spinal radiography was suspicious for possible intervertebral degenerative joint disease or discospondylitis. Despite prolonged medical therapy, the lameness progressed to minimal weight bearing and marked muscle atrophy of the right pelvic limb. Electromyography showed spontaneous activity in the muscles of right sciatic nerve distribution. Sensory and motor nerve conduction velocities in the right tibial and peroneal nerves were undetectable and markedly reduced, respectively. A magnetic resonance imaging (MRI) scan revealed a large, space-occupying mass on the right side of the sacrum and pelvis. Antemortem fine-needle aspiration of the mass and postmortem histopathology resulted in diagnosis of a high-grade squamous cell carcinoma of the anal sac. Squamous cell carcinoma of the anal sac is very rare in domestic dogs and previously unreported in spotted hyenas.

Lethal effects of water quality on threatened California salamanders but not on co-occurring hybrid salamanders.

Biological invasions and habitat alteration are often detrimental to native species, but their interactions are difficult to predict. Interbreeding between native and introduced species generates novel genotypes and phenotypes, and human land use alters habitat structure and chemistry. Both invasions and habitat alteration create new biological challenges and opportunities. In the intensively farmed Salinas Valley, California (U.S.A.), threatened California tiger salamanders (Ambystoma californiense) have been replaced by hybrids between California tiger salamander and introduced barred tiger salamanders (Ambystoma tigrinum mavortium). We conducted an enclosure experiment to examine the effects habitat modification and relative frequency of hybrid and native California tiger salamanders have on recruitment of salamanders and their prey, Pacific chorus frogs (Pseudacris regilla). We tested whether recruitment differed among genetic classes of tiger salamanders (hybrid or native) and pond hydroperiod (seasonal or perennial). Roughly 6 weeks into the experiment, 70% (of 378 total) of salamander larvae died in 4 out of 6 ponds. Native salamanders survived (n = 12) in these ponds only if they had metamorphosed prior to the die-offs. During die-offs, all larvae of native salamanders died, whereas 56% of hybrid larvae died. We necropsied native and hybrid salamanders, tested water quality, and queried the California Department of Pesticide Regulation database to investigate possible causes of the die-offs. Salamander die-offs, changes in the abundance of other community members (invertebrates, algae, and cyanobacteria), shifts in salamander sex ratio, and patterns of pesticide application in adjacent fields suggest that pesticide use may have contributed to die-offs. That all survivors were hybrids suggests that environmental stress may promote rapid displacement of native genotypes.

Effects of meloxicam on hematologic and plasma biochemical analysis variables and results of histologic examination of tissue specimens of Japanese quail (Coturnix japonica).

OBJECTIVE: To determine the effects of meloxicam on values of hematologic and plasma biochemical analysis variables and results of histologic examination of tissue specimens of Japanese quail (Coturnix japonica). ANIMALS: 30 adult Japanese quail. PROCEDURES: 15 quail underwent laparoscopic examination of the left kidneys, and 15 quail underwent laparoscopic examination and biopsy of the left kidneys. Quail in each of these groups received meloxicam (2.0 mg/kg, IM, q 12 h; n = 10) or a saline (0.9% NaCl) solution (0.05 mL, IM, q 12 h; control birds; 5) for 14 days. A CBC and plasma biochemical analyses were performed at the start of the study and within 3 hours after the last treatment. Birds were euthanized and necropsies were performed. RESULTS: No adverse effects of treatments were observed, and no significant changes in values of hematologic variables were detected during the study. Plasma uric acid concentrations and creatine kinase or aspartate aminotransferase activities were significantly different before versus after treatment for some groups of birds. Gross lesions identified during necropsy included lesions at renal biopsy sites and adjacent air sacs (attributed to the biopsy procedure) and pectoral muscle hemorrhage and discoloration (at sites of injection). Substantial histopathologic lesions were limited to pectoral muscle necrosis, and severity was greater for meloxicam-treated versus control birds. CONCLUSIONS AND CLINICAL RELEVANCE: Meloxicam (2.0 mg/kg, IM, q 12 h for 14 days) did not cause substantial alterations in function of or histopathologic findings for the kidneys of Japanese quail but did induce muscle necrosis; repeated IM administration of meloxicam to quail may be contraindicated.

Myenteric ganglionitis as a cause of recurrent colic in an adult horse.

CASE DESCRIPTION: A 10-year-old Lipizzaner stallion was evaluated over the course of 1.5 years because of intermittent, recurrent colic. CLINICAL FINDINGS: The horse was initially treated medically for gastric ulcers; dietary changes were made, and a deworming protocol was instituted, without resolution of colic episodes. Subsequently, the horse underwent exploratory celiotomy and a large colon volvulus was identified with diffuse colonic wall thickening. A pelvic flexure biopsy sample was submitted for histologic examination, which revealed lymphocytic (CD3-positive T cells) myenteric ganglionitis (MG). The horse developed a cecal impaction after surgery, which did not resolve, despite aggressive medical management; subsequently a complete cecal bypass was performed. Cecal and colonic wall biopsy samples were evaluated histologically and confirmed the diagnosis of MG. After surgery, the horse developed a large colon impaction, which initially responded to aggressive medical treatment, and the horse was discharged. TREATMENT AND OUTCOME: Despite rigorous feed restrictions and prokinetic and corticosteroid treatment, the horse continued to have signs of colic and was euthanized 3 weeks after discharge from the hospital because of a recurrent large colon impaction. Intestinal biopsy samples obtained at the time of death revealed chronic changes in intramural ganglia consistent with generalized MG. CLINICAL RELEVANCE: MG is a rare disease in horses, causing gastrointestinal motility dysfunction and signs of colic, which is challenging to diagnose and treat successfully. Further studies are needed to identify the etiology of this disease and to explore treatment options.

Disseminated pulmonary adiaspiromycosis in a crested porcupine (Hystrix cristata Linnaeus, 1758).

Adiaspiromycosis is primarily a necrotizing granulomatous pneumonia caused by a dimorphic fungus of the genus Emmonsia. A young crested porcupine (Hystrix cristata) found dead showed multiple fractures, chronic pleuritis, and granulomatous pneumonia. Microscopically, cystic structures were consistent with adiaspiromycosis by Emmonsia crescens. The diagnosis was confirmed using molecular methods.

Human metapneumovirus infection in wild mountain gorillas, Rwanda.

The genetic relatedness of mountain gorillas and humans has led to concerns about interspecies transmission of infectious agents. Human-to-gorilla transmission may explain human metapneumovirus in 2 wild mountain gorillas that died during a respiratory disease outbreak in Rwanda in 2009. Surveillance is needed to ensure survival of these critically endangered animals.

T-cell chronic lymphocytic leukemia in a double yellow-headed Amazon parrot (Amazona ochrocephala oratrix).

An adult, male double yellow-headed Amazon parrot (Amazona ochrocephala oratrix) was diagnosed with chronic lymphocytic leukemia based on results of a complete blood cell count and cytologic examination of a bone marrow aspirate. Treatment with oral chlorambucil was attempted, but no response was evident after 40 days. The bird was euthanatized, and the diagnosis of chronic lymphocytic leukemia was confirmed on gross and microscopic examination of tissues. Neoplastic lymphocytes were found in the bone marrow, liver, kidney, testes, and blood vessels. Based on CD3-positive immunocytochemical and immunohistochemical immunophenotyping, the chronic lymphocytic leukemia was determined to be of T-cell origin.

Polyomavirus infection in a free-ranging California sea lion (Zalophus californianus) with intestinal T-cell lymphoma.

An adult female California sea lion (Zalophus californianus) that stranded in central California was found to have a small glossal polypoid mass on gross necropsy. Histologically, the mass was consistent with a fibropapilloma, and intranuclear inclusions were found within endothelial cells lining small arterioles within the mass. Electron microscopy revealed 40-nm virions within endothelial intranuclear inclusions. Rolling circle amplification was used to obtain a partial viral genomic sequence. Sequence analysis identified the virus as a novel polyomavirus, tentatively named California sea lion polyomavirus 1. In addition, the sea lion had a severely thickened small intestine and swollen pale kidneys on gross examination. Severe renal amyloidosis with chronic interstitial nephritis was diagnosed histologically as well as T-cell intestinal lymphoma, which was confirmed via immunophenotyping and molecular clonality. The relationship, if any, between polyomavirus infection and the other disease processes in this sea lion is not known, but it is considered unlikely that the polyomavirus induced the lymphoma.

Morphologic, immunohistochemical, and molecular characterization of a novel Lankesterella protozoan in two White's tree frogs (Litoria caerulea).

Two White's tree frogs (Litoria caerulea) housed at a zoological park died after a short period of lethargy, weight loss, and edema. Detailed postmortem examinations were performed on both frogs, including bacterial cultures and complete histologic examinations. Intracytoplasmatic as well as free protozoan parasites were identified in multiple organs from both frogs. The parasites were identified within erythrocytes, leukocytes, endothelial cells, and hepatocytes. Immunohistochemistry demonstrated a cross-reaction with Toxoplasma gondii antisera. Parasite ultrastructural analysis was performed by transmission electron microscopy. The parasites demonstrated an apical complex containing a conoid, rhoptries, and micronemes, demonstrating it was a member of the phylum Apicomplexa. In addition, the parasites had bipolar paranuclear bodies, organelles that are typical of coccidian sporozoites. The organisms were tentatively identified as members of the genus Lankesterella on the basis of histologic and ultrastructural morphology. A portion of the 18s ribosomal RNA (rRNA) gene was amplified via a polymerase chain reaction, sequenced, and used in a Basic Local Alignment Search Tool search of the GenBank database. The 18s rRNA gene sequence was found to be most similar to gene sequences isolated from Lankesterella organisms (88%). In aggregate, these data support the classification of these protozoa as a novel species of Lankesterella. A causal relationship between frog morbidity and protozoal parasitism was not determined. This is the first report of Lankesterella sp. in White's tree frogs.

Detection of a respiratory coronavirus from tissues archived during a pneumonia epizootic in free-ranging Pacific harbor seals Phoca vitulina richardsii.

In June 2000, 21 adult harbor seals Phoca vitulina richardsii were found dead along a localized section of the central California coast. Necropsy of 5 fresh carcasses revealed pulmonary congestion, consolidation, and hemorrhage. Histopathological changes in lungs from 2 of these seals included a necrotizing lymphocytic and histocytic lobar pneumonia with intra-lesional bacteria. A coronavirus (CoV) was detected in archived tissues from 1 of the 5 seals via a degenerate PCR for nidoviral RNA-dependent RNA polymerase (RdRp), and was subsequently confirmed via specific PCR. Based on the partial RdRp sequence, the CoV was identified as a novel, divergent member of the CoV group 1a. The virus is tentatively named harbor seal coronavirus (HSCoV). The clinical significance of HSCoV and its involvement in the etiology of the epizootic pneumonia and deaths of the harbor seals is uncertain.

West Nile virus infection in a green-winged macaw (Ara chloropterus).

A 29-year-old female green-winged macaw (Ara chloropterus) was presented for acute pelvic limb lameness. On physical examination the bird was found to be mildly dehydrated with paraparesis and proprioceptive deficits of the pelvic limbs. Antemortem diagnostics included a complete blood count and plasma biochemistry panel, fecal Gram and Ziehl-Neelsen acid fast stains, plasma heavy metal concentrations, reverse transcriptase (RT)-PCR testing for West Nile virus (WNV) RNA and PCR testing for Chlamydophila psittaci DNA from choanal/cloacal swabs, and survey radiography. Abnormal findings included a heterophilic leukocytosis, elevated kidney and muscle enzyme values, and a positive RT-PCR result for West Nile viral RNA. Although the bird showed some improvement with supportive care, on the fourth day it began having seizures and was euthanatized. There were no abnormal findings detected on gross necropsy; however, histopathology revealed mononuclear inflammatory cell infiltration in multiple organs including brain, heart, and pancreas. WNV antigen and RNA were detected using immunohistochemistry and RT-PCR in various tissues including brain, pancreas, and spleen. WNV was successfully isolated from brain, pancreas, spleen, and liver. To our knowledge, this is the first report characterizing WNV disease in a green-winged macaw and one of few reports of this disease in a psittacine bird.