Unusual cases of chlamydiosis in psittacine birds.

Avian chlamydiosis is a common disease found in domesticated and nondomesticated avian species caused by several species of chlamydiae including but not limited to Chlamydia psittaci, Chlamydia avium, Chlamydia gallinacea, Chlamydia buteonis, and Chlamydia ibidis. Generally, early in the disease course, birds present with mild nonspecific clinical signs associated with gastrointestinal and respiratory tract disease. During end-stage disease, birds may present in a severe state of emaciation, dehydration, and/or acute death with no known history of prior illness. Between 2000 and 2009, 14 unusual cases of avian chlamydiosis were submitted to the California Animal Health and Food Safety Laboratory System. Histologic lesions noted in the 14 birds included meningoencephalomyelitis (3 of 13, 23%), otitis media (3 of 8), bursitis (9 of 11, 81%), nephritis (8 of 13, 61%), and orchitis (1 of 8). Corresponding immunopositive chlamydiae intracytoplasmic inclusions were detected in all tissues. Positive immunolabeling was detected in optic nerves (5 of 10, 50%), meninges (5 of 13, 38%), and endothelial cells (14 of 14, 100%) in the absence of significant microscopic lesions. This study highlights unusual gross, histological, and immunohistochemical findings of chlamydiosis in psittacines and highlights the importance of a thorough diagnostic approach when confirming or excluding chlamydiosis in psittacine birds.

Infectious laryngotracheitis of chickens: Pathologic and immunohistochemistry findings.

Infectious laryngotracheitis (ILT) is an important upper respiratory disease of chickens. Gross and histologic lesions of ILT in chickens are compared to immunohistochemistry to evaluate the diagnostic test sensitivity. A total of 31 separate ILT-confirmed necropsy submissions (12 commercial meat-type flocks, 13 egg-type producers, and 6 backyard flocks) were arbitrarily selected. Each submission ranged from 1 to 18 birds, for a total of 246 chickens. Cases with available formalin-fixed tissues were selected to include a range of bird production types, ages, clinical histories, and severity of macroscopic and histologic lesions. Macroscopic findings in the respiratory tract varied from increased mucus (55.6%) to fibrinonecrotic exudate (20.3%) and hemorrhages in the larynx and trachea (13.0%). Syncytia with intranuclear inclusion bodies were present in the respiratory tract epithelium with or without hemorrhages. Sections of conjunctiva, sinus, larynx, trachea, lung, and air sac were analyzed by immunohistochemistry (IHC) to detect gallid alphaherpesvirus 1 (GaHV-1) antigen. Positive immunolabeling was detected in the cytoplasm and nuclei of syncytia and epithelial cells in 18/22 conjunctivae (82%), 12/13 sinuses (92%), 18/22 larynxes (82%), 23/25 tracheas (92%), 10/21 lungs (57%), and 3/8 air sacs (37%). Of the 34 tissues with no visible syncytia or inclusion bodies, 8 were positive by IHC. In conclusion, IHC was useful to study the viral antigen tissue distribution and support the diagnosis of ILT when the histopathologic interpretation was doubtful.

Non-Clostridium perfringens infectious agents producing necrotic enteritis-like lesions in poultry.

Necrotic enteritis (NE) produced by Clostridium perfringens is amongst the most prevalent enteric diseases of chickens and turkeys. However, several other bacterial, parasitic and viral agents can cause clinical signs, gross and microscopic lesions in poultry very similar to those of NE and the diseases produced by those agents need to be differentiated from NE. The main differential diagnoses for C. perfringens NE include bacterial (Clostridium colinum, Clostridium sordellii, Clostridium difficile, Pasteurella multocida, Brachyspira spp.), parasitic (Eimeria spp., Histomonas meleagridis) and viral (Duck Herpesvirus type 1, Avian Paramyxovirus type 1) diseases. Confirmation of the diagnosis of these diseases requires identification of the aetiological agents by morphological, cultural and/or molecular methods.

Trichodinosis associated with pathology of the reproductive tract in waterfowl.

Trichodinid ciliophorans are opportunistic parasites of many species of fish, amphibians, and molluscs, but yet never reported in association with lesions in birds. Postmortem and histopathological evaluation of a commercial adult Toulouse gander and female goose, and a wild Mallard drake revealed the presence of severe pathological parasitic colonization of their reproductive tracts. Histopathological findings included moderate to severe granulocytic inflammation, acanthosis, accentuation of the rete pegs, and proliferative hyperplastic squamous metaplasia of the mucosa of the ejaculatory ducts and groove, sulcus spermaticus, glandular part of the phallus (cavum penis), and oviduct in association with large numbers of ciliated protozoa anchored to the tissues or free in the lumen. These protozoa had characteristic morphological features analogous to the family of Trichodinidae. The source of this parasitism could not be determined. To our knowledge, this is the first report of trichodinosis associated with pathology in birds.

Myopathy of the Pipping Muscles, Hepatosis Dietetica, and Cataracts in Emu Chicks (Dromaius Novaehollandiae).

Seven emu chicks (Dromaius novaehollandiae) from a farm with poor hatchability (16-18%) and increased neonatal mortality were presented for necropsy with a history of death at or within a few days after hatching. Macroscopic examination revealed subcutaneous edema and hemorrhages and swelling of the pipping muscles in the proximal neck (71%), pale liver with hemorrhages (71%), noninternalized residual yolk sac (86%) and anasarca (14%). Histologically, the most remarkable findings were necrosis of the musculus complexus (100%) of the pipping muscles, as well as myocardial necrosis and mineralization (29%). Liver contained severe multifocal hepatocellular necrosis and hemorrhages (57%), and both eyes exhibited swollen and vacuolated lenticular fibers in 5 chicks (100%) in which the eyes were examined. The lesions observed here are suggestive of a nutritional deficiency. The deficiency was confirmed by finding low levels of vitamin E in the liver, and vitamin E and vitamin A levels in the feed.

Cutaneous mucinosis in a strain of brown-egg laying chickens.

Cutaneous mucinosis is a cutaneous disorder described in humans, dogs, and rarely cats but never reported in birds. Twenty-six brown egg-laying chickens between ages 43 and 46 weeks had a history of feather loss, scaly, dry skin, weight loss, and decreased egg production. Microscopic findings in the skin included fragmentation of collagen bundles and interstitial, periadnexal, and perivascular dermal accumulation of wispy, mildly basophilic material that was also occasionally observed within the follicular epithelium. A moderate lymphoplasmacytic and heterophilic perivascular dermatitis was also observed. The wispy to granular material was diffusely Alcian blue positive and periodic acid-Schiff negative (consistent with mucin), suggesting a diagnosis of primary or secondary cutaneous mucinosis. The cause of this condition could not be determined.

Pathological and biochemical studies of mucopolysaccharidosis type IIIB (Sanfilippo syndrome type B) in juvenile emus (Dromaius novaehollandiae).

Mucopolysaccharidosis (MPS) type IIIB was diagnosed in 14 juvenile emus (Dromaius novaehollandiae), ages 3 weeks to 6 months, based on pathological and biochemical analyses. The animals had a history of neurological signs or sudden death; one of the birds with neurological signs and 3 others experienced acute hemoabdomen. Histopathologically, neuronal swelling and vacuolation in the cerebrum, cerebellum, brainstem, and spinal cord (80%-92%); retina (100%); autonomic ganglia of the intestine (71%); gizzard (50%); adrenal gland (27%); and ear (50%) were noted in affected but not healthy emus. Cytoplasmic vacuoles were also observed in the pancreas, liver, intestine, adrenal glands, and kidneys. The intracytoplasmic inclusions were periodic acid-Schiff and Luxol Fast Blue positive, consistent with a storage disease. Foamy macrophages infiltrated the liver, intestine, tunica media of the aorta, and spleen. By transmission electron microscopy, typical lamellated cytoplasmic bodies were detected in neurons of the brain and retina, while electron-dense bodies consistent with glycosaminoglycan inclusions were observed in hepatocytes and/or hepatic macrophages. The livers of the 2 affected emus studied contained large amounts of heparan sulfate, which is suggestive of MPS type III. Compared with normal controls, hepatic and serum α-N-acetylglucosaminidase activity was very low (<8% of control), while other enzyme activities were normal to increased in the 2 affected emus studied. Moreover, affected emus were homozygous for a 2-bp deletion in the NAGLU gene. This study characterizes the pathology of MPS type IIIB in emus, which is one of the rare inborn errors in birds, showing the homology of this condition to Sanfilippo syndrome in humans.

Runting Stunting Syndrome Associated with Transmissible Viral Proventriculitis in Broiler Chickens.

This report describes an outbreak of transmissible viral proventriculitis (TVP) associated with runting stunting syndrome (RSS) in 25- and 28-day-old broiler chickens, in which chicken proventricular necrosis virus (CNPV) was detected. Clinical signs included poor uniformity, very small birds for their age, increased mortality, and culling of smaller birds. Almost all birds necropsied exhibited moderate to severely enlarged proventriculi with diffusely pale serosa and thickened walls. Microscopically the proventriculi had lesions of degeneration and necrosis of the epithelium of the proventricular glands, accompanied by lymphocytic inflammation and glandular hyperplasia, with occasional formation of lymphoid nodules within the glandular parenchyma. Immunohistochemistry staining for CPNV was positive. Positive staining was generally found in the cytoplasm of glandular epithelial cells in the form of finely granular brown pigment. CPNV RNA was detected in the proventriculi by reverse transcriptase-PCR (RT-PCR). Other findings included mild enteritis in a few birds and small bursa of Fabricius. Direct electron microscopy performed on the intestinal samples was negative for viral particles. RT-PCR analysis of bursae was positive for infectious bursal disease virus (IBDV). In conclusion, this report associates TVP with RSS by describing an outbreak in which TVP attributable to CPNV was the most commonly found lesionin chickens with a clinical history compatible with RSS. Therefore, TVP should be considered as a possible differential diagnosis in cases compatible with RSS.

Retrospective Study on the Isolation of Ornithobacterium rhinotracheale from Chickens and Turkeys in Central California: 294 cases (2000-12).

Ornithobacterium rhinotracheale is a rod-shaped, gram-negative, and mostly oxidase-positive bacterium that causes respiratory infections in chickens and turkeys worldwide and can also spread to nonrespiratory organs. The present report analyzes 294 cases in which O. rhinotracheale was isolated from turkeys or chickens in central California in the years 2000 through 2012. Two hundred sixteen cases were from turkey flocks and 78 from chicken flocks. The median age of turkey flocks was 8.7 wk; the median age of chicken flocks was 6.4 wk. From turkeys, O. rhinotracheale was more often isolated from August to January than during the rest of the year. Chickens cases were more evenly distributed throughout the year. The organs with the highest isolation rate were the infraorbital sinus and trachea, followed by lungs and air sacs. Isolation from other organs was rare. Pure cultures were obtained from relatively more turkey organs than chicken organs. The organ from which there was the highest chance to obtain a pure culture was the air sac. In 108 turkey flocks (50.0%) and 64 chicken flocks (82.1%) at least one other respiratory pathogen was detected. The most common gross lesions were increased mucus in trachea, caseous or fibrinous exudate in the air sacs, consolidated lungs indicating pneumonia, congested and edematous lungs, and a flattened trachea. For most types of lesions, the percentage of affected turkeys was higher than the percentage of affected chickens. The percentage of birds with lesions was higher if other respiratory pathogens were present. Overall, the host species (turkey or chicken) was a more important factor for the prevalence of most lesions than the detection of other respiratory pathogens. The most common histopathologic lesions in the sinus and trachea were heterophilic or mononuclear inflammatory cell infiltration. In the lungs and air sacs, the inflammation was characterized by heterophilic infiltration and/or fibrin accumulation. These results are helpful in selecting the most appropriate samples for isolation of O. rhinotracheale. In addition, they show the incidence of the bacterium in turkeys and chickens and which lesions can be expected after infection with O. rhinotracheale, and they indicate that in some cases O. rhinotracheale can be the primary, or at least the major, pathogen.

An Unusual Outbreak of Chlamydiosis in Commercial Turkeys Involving the Nasal Glands.

An unusual outbreak of chlamydiosis was diagnosed in 15,000, 13-wk-old organically grown turkeys housed in a semiconfinement housing system. The disease was characterized by unilateral or bilateral swelling above the eye due to mild-to-severe inflammation of the nasal glands in 3%-5% of the birds. Except for a slight drop in feed and water consumption, the birds did not exhibit any respiratory signs, morbidity, and mortality. Chlamydiosis in the turkeys was confirmed by immunofluorescence, immunohistochemistry, and PCR assay of the nasal glands. Other samples such as conjunctiva, lungs, air sacs, heart, liver, spleen, and feces were negative for chlamydia by florescence antibody test in birds submitted over several weeks. Chlamydia psittaci strain B was isolated in chicken egg embryos and typed by multilocus sequence variable number of tandem repeats analysis, multilocus sequence typing, and ompA gene sequencing as a CP3-like strain. This is the first report of a naturally occurring chlamydiosis affecting the nasal glands in turkeys.

Necrotic Enteritis in Chickens Associated with Clostridium sordellii.

Three outbreaks of necrotic enteritis-like disease associated with Clostridium sordelii were diagnosed in commercial broiler chicken flocks with 18,000 to 31,000 birds between 18 and 26 days old. Clinical signs in the affected flocks included high mortality up to 2% a day, depression, and diarrhea. The main gross changes included segmental dilation of the small intestine with watery contents, gas, mucoid exudate, and roughened and uneven mucosa, occasionally covered with a pseudomembrane. Microscopic lesions in the small intestine were characterized by extensive areas of coagulative necrosis of the villi, fibrinous exudate in the lumen, and high numbers of large, Gram-positive rods, occasionally containing subterminal spores, seen in the necrotic tissue and lumen. These rods were identified as C. sordellii by immunohistochemistry. Clostridium sordellii was isolated in an almost pure culture from the intestine of affected birds. A retrospective study of commercial broiler chicken and turkey submissions to the California Animal Health and Food Safety Laboratory System revealed that C. sordellii had been isolated from intestinal lesions in outbreaks of necrotic enteritis-like disease in 8 of 39 cases, 5 times together with Clostridium perfringens and 3 times alone. The latter three cases are reported here.

Bilateral Malignant Seminomas in Two Unrelated, Aged Trumpeter Hornbills (Bycanistes buccinator).

Seminomas occur infrequently in birds. Two cases of bilateral malignant seminomas in unrelated trumpeter hornbills (Bycanistes buccinator) are described. Case 1 was a 22-year-old trumpeter hornbill submitted for necropsy because of sudden death at a zoo in California. Postmortem examination revealed multiple masses within the body cavity, 2 of which replaced both testes. Case 2 was a 19-year-old trumpeter hornbill at a zoo in North Carolina that underwent exploratory surgery for a suspected gastrointestinal obstruction. Both testes were diffusely enlarged, compressing and replacing the adjacent kidneys. In both birds, the masses were composed of discrete, round to polyhedral cells, typical of seminomas. Examination of the ancestry of the hornbills showed they were unrelated to each other, suggesting a potential predisposition for these birds to develop seminomas.

Characterization of a new genotype of avian bornavirus from wild ducks.

BACKGROUND: Avian bornaviruses (ABV) are a recently described group of intranuclear negative-stranded RNA viruses (Order Mononegavirales, Family Bornaviridae). At least 13 different ABV genotypes have been described. One genotype, the Canada goose genotype (ABV-CG), has been isolated from geese and swans and is widely distributed across North America. RESULTS: We have isolated and characterized a previously undescribed genotype of avian bornavirus from the brains of wild ducks. This new genotype, provisionally designated ABV genotype MALL, was detected in 12 of 83 mallards, and 1 of 8 wood ducks collected at a single location in central Oklahoma. The virus was cultured on primary duck embryo fibroblasts, fragments were cloned, and its genome sequence of 8904 nucleotides determined. This new genotype has 72% nucleotide identity and 83% amino acid identity with the ABV-CG genotype previously shown to be present in geese and swans. Histologic and immunohistochemical examination of the brains and eyes of four positive ducks indicated the presence of virus-infected neurons and glia in their cerebrums and retinas in the absence of inflammation. CONCLUSIONS: More than one genotype of ABV is circulating in North American waterfowl. While the infected ducks were not observed to be suffering from overt disease, based on the immunohistochemistry, we speculate that they may have suffered some visual impairment.

Investigating a crow die-off in January-February 2011 during the introduction of a new clade of highly pathogenic avian influenza virus H5N1 into Bangladesh.

We investigated unusual crow mortality in Bangladesh during January-February 2011 at two sites. Crows of two species, Corvus splendens and C. macrorhynchos, were found sick and dead during the outbreaks. In selected crow roosts, morbidity was ~1 % and mortality was ~4 % during the investigation. Highly pathogenic avian influenza virus H5N1 clade 2.3.2.1 was isolated from dead crows. All isolates were closely related to A/duck/India/02CA10/2011 (H5N1) with 99.8 % and A/crow/Bangladesh/11rs1984-15/2011 (H5N1) virus with 99 % nucleotide sequence identity in their HA genes. The phylogenetic cluster of Bangladesh viruses suggested a common ancestor with viruses found in poultry from India, Myanmar and Nepal. Histopathological changes and immunohistochemistry staining in brain, pancreas, liver, heart, kidney, bursa of Fabricius, rectum, and cloaca were consistent with influenza virus infection. Through our limited investigation in domesticated birds near the crow roosts, we did not identify any samples that tested positive for influenza virus A/H5N1. However, environmental samples collected from live-bird markets near an outbreak site during the month of the outbreaks tested very weakly positive for influenza virus A/H5N1 in clade 2.3.2.1-specific rRT-PCR. Continuation of surveillance in wild and domestic birds may identify evolution of new avian influenza virus and associated public-health risks.

Ulcerative dermatitis and valvular endocarditis associated with Staphylococcus aureus in a hyacinth macaw (Anadorhynchus hyacinthinus).

An 18-yr-old male hyacinth macaw (Anadorhynchus hyacinthinus) was found dead in his aviary with no preexisting signs. The bird had a chronic history of feather damaging behavior, with severe ulcerative dermatitis. Pathologic findings revealed a vegetative valvular endocarditis, myocarditis, septicemia, chronic severe glomerulonephritis, and thyroid dysplasia. Staphylococcus aureus was isolated from the valve, the liver, and the skin. Repeated trauma and low-rate bacteriemia may have contributed to the development of endocarditis. Translocation of S. aureus skin infection in the bloodstream may lead to subacute endocarditis in humans and such mechanism is suspected in this case. This case suggests that endocarditis associated with S. aureus septicemia is a potential complication of feather damaging behavior. This case also reports a systemic complication of ulcerative dermatitis secondary to feather damaging behavior. Endocarditis has been poorly reported in psittacine species, and such medical complication of feather damaging behavior has never been reported to our knowledge. Furthermore, S. aureus is a bacteria of public health concern and should be integrated into the differential when pet parrots with dermatitis are in proximity to owners.

Retrospective study of turkey viral hepatitis in California turkey flocks, 2000-2012.

Turkey viral hepatitis (TVH) is a disease characterized by an inflammation of the liver, and occasionally of the pancreas, of turkeys. Little is known about the occurrence of TVH in turkey flocks; thus, the aim of the present article is to summarize retrospectively 76 cases of TVH diagnosed at the California Animal Health and Food Safety System (CAHFS), University of California, Davis, in the years 2000 through 2012. Flocks diagnosed with TVH were between 7 and 61 days old, with an average age of 29.4 days and a median age of 28 days. In the majority of cases, increased mortality was reported. In 55 cases, gross lesions were present in the liver; the most common lesions were a few to numerous pale white foci in 35 cases. In livers of 74 cases, histologic lesions were observed. Multifocal necrosis with inflammation was observed in livers of 42 cases, inflammation but no necrosis in 22 cases, and necrosis without inflammation in 8 cases. In 17 cases, pale white foci were found in the pancreas; in 4 cases, larger areas of the organ were pale. In 33 cases, histologic changes were observed in the pancreas. Necrosis with inflammation was observed in the pancreas of 17 cases, necrosis without inflammation in 7 cases, and inflammation without necrosis in 9 cases. No Salmonella was isolated from any of the livers cultured. Transmission electron microscopy of liver and pancreas demonstrated viral particles between 23 and 25 nm in two cases. Concurrent diseases were mostly poult enteritis (65 cases), but also respiratory diseases and colibacillosis. TVH occurred more often in turkeys during winter months. In conclusion, TVH was observedon a regular basis in California turkey flocks during the last 12 yr.

An outbreak of blindness due to retinopathy in nine flocks of guinea fowl.

Blindness was observed in 10- to 14-day-old guinea fowl. The incidence ranged from 25% to 80% in nine flocks within a total population of 110,000 guinea fowls. Clinical signs of blindness in birds included aimless wandering, failure to find feed and water, lateral recumbency, loss of weight, and increased mortality. The birds lacked papillary reflexes to light, and there were no gross lesions in the eyes. Histologically there was degeneration and disorganization of photoreceptors in the retina. The guinea fowl came from three different breeder sources but all of the birds were given the same feed. The condition was not observed in the subsequent flocks that came from the same breeder sources but that were given different feed. Based on these observations, toxicity of an unknown ingredient in the feed is suspected as the cause of blindness in the guinea fowl.

Spatial and temporal epidemiology of infectious laryngotracheitis in central California: 2000-2012.

In October of 2005 an outbreak of a vaccine-like strain of infectious laryngotracheitis (ILT), indistinguishable from the chicken embryo origin (CEO)-like vaccine strains, was detected by routine passive surveillance in the Central Valley of California, U. S. A. In response, a highly coordinated industry effort by two companies led to a significant decrease in the incidence of ILT over the same geographic region between 2008-2012. In order to understand the geographic and temporal spread of ILT in California before and after the outbreak, Global Information Systems (GIS) mapping coupled with spatial, temporal, and spatial- temporal statistics were used to identify retrospective and prospective low-rate clustering (i.e., less ILT than statistically expected) and high-rate clustering (i.e., more ILT than statistically expected) of ILT spatially and temporally. Results showed two high-rate retrospective spatial-temporal clusters and one low-rate prospective spatial-temporal cluster which were all statistically significant (P < 0.05). Overall, spatial-temporal clustering accounted for 36.9% of the positive ILT cases, while temporal clustering and spatial clustering done separately each accounted for 0% of the ILT cases, respectively. This demonstrates the utility of combining spatial and temporal clustering for ILT surveillance. Due to the risk of reversion to virulence and spread to immunologically naive broilers, future application of the CEO-based vaccine in the identified high rate spatial-temporal clusters should be avoided and other vaccine alternatives considered in order to avoid repeat outbreaks in those areas. This should especially be followed during the winter months of December, January, and February, which were found to have the highest prevalence of ILT (P < 0.05). Analysis of GIS data within the high-rate clusters showed that wind direction and farm density were minor factors in the spread of ILT. Shared roads may have played a role in the spread of ILT in one of the two high rate spatial-temporal clusters.

Tribasic copper chloride toxicosis in commercial broiler chicks.

Two broiler chicken houses containing 17,500 chicks each experienced an extreme elevation in chick mortality beginning on day 3 after placement. Clinical signs observed upon farm visit included numerous small chicks for their age; depressed, lethargic, and comatose chicks; and chicks huddling near feed pans and under heaters. Necropsied chicks were markedly pale and had atrophy of the thymus and bursa, swollen and edematous proventriculus, erosions in the koilin and in the proventricular-ventricular junction, pale kidneys, and yellowish to brownish-orange liver often with linear pale areas. The chicks had watery blood and hematocrits measured from 9.5% to 18%. Chicken infectious anemia was initially suspected based on the clinical signs and gross lesions. Histopathology revealed multifocal acute hepatic degeneration and necrosis with golden-brown pigment in the cytoplasm of hepatocytes and Kupffer cells, moderate to severe koilin degeneration and fragmentation, multifocal mild to moderate proventricular necrosis, mild to moderate necrosis and loss of enterocytes, blunting of small intestinal villi, lymphoid depletion in the thymus and bursa, erythrophagocytosis in the liver and spleen, and acute renal tubular degeneration and necrosis. Special stains revealed mild to abundant accumulation of copper pigment in the cytoplasm of hepatocytes and iron pigment in the cytoplasm of Kupffer cells. Feed analysis revealed 2140 to 2393 parts per million of copper in the starter ration, and heavy metal analysis detected markedly elevated copper levels in formalin-fixed samples of the liver. Excessive amounts of tribasic copper chloride in the starter ration caused copper toxicosis in these chicks. Similar clinical signs and lesions were reproduced when the suspect feed was used in an experimental pen trial.

Fatal proventricular dilatation disease in captive native psittacines in Brazil.

An outbreak of proventricular dilatation disease (PDD), a fatal inflammatory disease of psittacines (Aves: Psittaciformes), is described in native Brazilian psittacines. Twenty captive psittacines that died of suspected PDD were necropsied and 10 were submitted to histopathology, reverse transcriptase PCR (RT-PCR), and immunohistochemistry (IHC) for avian bornavirus (ABV). Examined species were one pileated parrot (Pionopsitta pileata), three vinaceous-breasted parrots (Amazona vinacea), two blue-winged macaws (Primolius maracana), one scarlet macaw (Ara macao), one chestnut-fronted macaw (Ara severa), one scaly-headed parrot (Pionus maximiliani), and one red-browed Amazon parrot (Amazona rhodocorytha). Gross examination and histopathology revealed typical PDD lesions in all birds. The presence of ABV was confirmed in four psittacines including one red-browed Amazon parrot, one blue-winged macaw, one scarlet macaw, and one chestnut-fronted macaw. In the red-browed Amazon parrot and in one blue-winged macaw, IHC demonstrated ABV antigens in the nucleus and cytoplasm of cells in various organs. This is the first description of PDD by ABV in Brazilian psittacines and indicates the necessity for adopting a strategic control plan for reducing its impact in native birds.