Psittacid herpesviruses associated with mucosal papillomas in neotropical parrots

Survey of the Clinical, Cytological, and Histopathological Features Associated with Neoplasms in Captive Avian Species in Melbourne, Australia

Over a 3.5-year period, tissue samples from 141 companion and aviary birds with clinically suspected, naturally occurring solid neoplasms were collected via surgical biopsy (n = 53) or at necropsy examination (n = 88) from a population of birds presenting to an avian veterinary clinic in Melbourne, Australia. Neoplastic processes were identified in 73.7% (n = 104) of samples, with 83.7% (n = 87) being interpreted as malignant neoplasia and 16.3% (n = 17) being interpreted as benign neoplasia. The overall estimated prevalence of neoplasia in the study population (n = 5125) was 2.45% (95% confidence interval, 2-2.97%). The gastrointestinal and reproductive tracts were the most commonly affected systems. The most common presenting signs were nonspecific and included lethargy, coelomic distension, and inappetence. In 59 cases, fine-needle aspirates (FNAs) and impression smears were also obtained and evaluated cytologically. The accuracy of cytology for detecting neoplasia in birds and for determining whether a neoplastic process was benign or malignant was assessed by using histopathology as the "gold standard." There was complete agreement between the cytological and histopathological diagnoses in 72.8% (43/59) of cases. Cytology correctly identified 87.5% of these cases (35/40) as malignant neoplasms and 55.6% (5/9) as benign processes. There was no significant difference between the use of cytology and histopathology for the detection of malignant neoplasia in birds (P = 0.185). The accuracies of FNAs and impression smears for examining avian tumors were also compared. Overall, the best cell preservation was obtained by performing impression smears from tissues, with 62.2% (n = 28) returning high cellularity for cytological examination, compared to 53.8% (n = 14) when samples were obtained by FNA. This study provides an overview of the types and prevalence of neoplasms in a captive bird population from Australia, correlates physical examination findings with tumor types, and provides evidence that cytology is a reliable preliminary diagnostic tool for detecting neoplasia in birds.

Detection of a Novel Alphaherpesvirus and Avihepadnavirus in a Plantar Papilloma from a Rainbow Lorikeet (Trichoglosis moluccanus)

Cutaneous plantar papillomas are a relatively common lesion of wild psittacine birds in Australia. Next-generation sequencing technology was used to investigate the potential aetiologic agent(s) for a plantar cutaneous papilloma in a wild rainbow lorikeet (Trichoglosis moluccanus). In the DNA from this lesion, two novel viral sequences were detected. The first was the partial sequence of a herpesvirus with the proposed name, psittacid alphaherpesvirus 6, from the Mardivirus genus of the family alphaherpesviruses. This represents the first mardivirus to be detected in a psittacine bird, the first mardivirus to be detected in a wild bird in Australia, and the second mardivirus to be found in a biopsy of an avian cutaneous papilloma. The second virus sequence was a complete sequence of a hepadnavirus, proposed as parrot hepatitis B genotype H (PHBV-H). PHBV-H is the first hepadnavirus to be detected in a wild psittacine bird in Australia. Whether other similar viruses are circulating in wild birds in Australia and whether either of these viruses play a role in the development of the plantar papilloma will require testing of biopsies from similar lesions and normal skin from other wild psittacine birds.

Phylogenetically under-dispersed gut microbiomes are not correlated with host genomic heterozygosity in a genetically diverse reptile community

While key elements of fitness in vertebrate animals are impacted by their microbiomes, the host genetic characteristics that factor into microbiome composition are not fully understood. Here, we correlate host genomic heterozygosity and gut microbiome phylogenetic diversity across a community of reptiles in southwestern New Mexico to test hypotheses about the behaviour of host genes that drive microbiome assembly. We find that microbiome communities are phylogenetically under-dispersed relative to random expectations, and that host heterozygosity is not correlated with microbiome diversity. Our analyses reinforce results from functional genomic work that identify conserved host immune and nonimmune genes as key players in microbiome assembly, rather than gene families that rely on heterozygosity for their function.

Herpetic Pneumonia in Indian Ringneck Parrots (Psittacula krameri): First Report of Novel Psittacid Alphaherpesvirus-5 Infection in Europe

The first two European outbreaks of herpetic pneumonia caused by Psittacid alphaherpesvirus-5 were diagnosed based on gross pathology findings, histological examination, transmission electron microscopy visualization and genome sequencing. The outbreaks, characterized by high morbidity and high mortality rates, involved two parrot species, namely the Indian ringneck parrot (Psittacula krameri) and the Alexandrine parakeet (Psittacula eupatria). Clinical signs observed were ruffled feathers, dyspnea, tail bobbing, open wings while breathing, depression and anorexia. Necropsy was performed on Indian ringneck parrots only, and the most evident and serious gross lesion found in all the birds was a diffuse marked consolidation of the lungs associated with parenchyma congestion and oedema. Histological examination confirmed the existence of bronchopneumonia characterized by the presence of syncytial cells with intranuclear inclusion bodies. In one bird, fibrinous airsacculitis was observed as well. Lung tissue inspection through electron microscopy revealed the presence of virus particles resembling herpesviruses. Viral DNA was extracted, amplified using primers for Alloherpesviridae DNA polymerase gene detection, and then sequenced. BLAST analysis showed a 100% identity with the only previously reported sequence of PsHV-5 (MK955929.1).

Alimentary squamous cell carcinoma in psittacines: 12 cases and review of the literature

Squamous cell carcinoma (SCC), which is a neoplasm that usually arises from the integument, is reported uncommonly in pet birds. Only a few reports of SCCs in the alimentary tract of birds, including psittacines, have been published, and a detailed description of the pathology is not available in the literature. We present here 12 cases of alimentary SCC in psittacines. The average age of the birds was 22.2 y (range: 15-29 y), and affected species included 4 Amazon parrots (Amazona sp.), 3 cockatiels (Nymphicus hollandicus), 3 macaws (Ara sp.), 1 conure (Eupsittula sp.), and 1 Senegal parrot (Poicephalus sp.). Frequent clinical complaints included regurgitation, dysphagia, dyspnea, lethargy, and/or weight loss. SCC primarily affected the oral cavity in 6 of 12 cases, the crop alone in 2 of 12 cases, the crop and esophagus in 1 of 12 cases, the proventriculus alone in 1 of 12 cases, and the crop, esophagus, and proventriculus in 2 of 12 cases. Histologically, alimentary SCCs were locally invasive and often resulted in mucosal ulceration. Although there were no metastases in any of our cases, poor clinical outcomes were frequent and associated most commonly with complete effacement of the alimentary segment and severe inflammation with opportunistic bacterial infection. Our review of the literature records commonly affected species, variability of gross presentations and clinical signs, plausible etiologies, and current diagnostic developments.

Disseminated pancreatic adenocarcinoma in an eclectus parrot (Eclectus roratus)

CASE DESCRIPTION

A 15-year-old 0.412-kg (0.906-lb) sexually intact male eclectus parrot (Eclectus roratus) was evaluated because its owners found it lethargic and dyspneic at the bottom of its cage.

CLINICAL FINDINGS

The parrot was thin and had generalized muscle wasting, diffuse feather loss, pale mucous membranes, and melena. The coelomic cavity was distended and soft on palpation, with coelomic effusion suspected. Results of a CBC indicated leukocytosis with left shift heterophilia, including toxic heterophils, lymphopenia, and anemia. Plasma biochemical analyses revealed severe hyperamylasemia.

TREATMENT AND OUTCOME

Radiography revealed no evidence of a metallic foreign body but severe loss of coelomic detail, suggestive of a coelomic mass, coelomic effusion with coelomitis, or both. Ultrasonography and CT revealed severe accumulation of coelomic fluid; a large, heterogeneous, irregularly marginated, and moderately vascularized mass in the caudal aspect of the coelomic cavity; and multiple hepatic, coelomic, and pulmonary nodules. On the basis of a poor prognosis, the parrot was euthanized. Necropsy results confirmed exocrine pancreatic adenocarcinoma, with disseminated metastases in the liver, gastrointestinal tract, coelomic cavity, and lungs.

CLINICAL RELEVANCE

In birds, pancreatic adenocarcinoma is rarely reported but should be considered a differential diagnosis for hyperamylasemia, coelomic mass, coelomic effusion, or abnormal gastrointestinal signs, alone or in combination. Ultrasonography and CT can be useful in further evaluating such patients and should be considered in the diagnostic plan.

Avian Papilloma and Squamous Cell Carcinoma: a Histopathological, Immunohistochemical and Virological study

In this retrospective study, we describe the histopathological findings in seven papillomas and 45 squamous cell carcinomas (SCCs) from psittacine birds, raptors and domestic fowl. The age of affected birds ranged from 3 to 40 years, with median age significantly higher in psittacines (P = 0.014). The majority of tumours were located in the skin (24/52, 46.2%) or uropygial gland (10/52, 19.2%). Thirty of the SCCs (66.7%) were well differentiated and 15 (33.3%) were poorly-differentiated. SCCs exhibited a significantly higher degree of nuclear pleomorphism (P = 0.005) and a greater proportion were ulcerated (P = 0.001) compared with papillomas; however, there was no significant difference in mitotic count (MC) or inflammation score. The expression of cyclo-oxygenase (COX)-2 and E-cadherin was investigated by immunohistochemistry. The COX-2 total score (TS) was significantly higher in SCCs compared with papillomas (P = 0.002), but the difference between COX-2 TS of well- and poorly-differentiated SCCs was not significant. COX-2 labelling was predominantly cytoplasmic, but some tumours had concurrent membranous and/or perinuclear labelling. SCCs with membranous labelling had a significantly higher MC (P = 0.028). A significantly higher proportion of SCCs were negative for E-cadherin compared with papillomas (P = 0.042), but there was no significant difference between well- and poorly-differentiated SCCs. Fourteen papillomas and SCCs from psittacines were also tested by polymerase chain reaction for the presence of Psittacus erithacus papillomavirus 1 and Psittacid herpesvirus 1, but all samples tested negative. We demonstrate for the first time the expression of COX-2 and E-cadherin in avian tissues, and suggest that these markers may be useful in differentiating papillomas from SCCs, particularly when sample size is small.

Oxidative stress biomarkers are associated with visible clinical signs of a disease in frigatebird nestlings

Infectious diseases are one of the most common threats for both domestic and wild animals, but little is known about the effects on the physiological condition and survival of wild animals. Here, we have tested for the first time in a wild vertebrate facing a viral disease possibly due to herpesvirus (i) whether nestlings with either low levels of oxidative damage or high levels of antioxidant protection are less susceptible to develop visible clinical signs, (ii) whether the disease is associated with the nestlings’ oxidative status, (iii) whether the association between the disease and oxidative status is similar between males and females (iv), and whether cloacal and tracheal swabs might be used to detect herpesvirus. To address our questions, we took advantage of a population of Magnificent frigatebirds (Fregata magnificens) whose nestlings have experienced high mortality rates in recent times. Our work shows that (i) blood lipid oxidative damage is associated with observable clinical signs and survival probabilities of nestling frigatebirds, and (ii) that high glutathione levels in red blood cells are associated with the emergence of visible clinical signs of the disease. Our work provides evidence that differences in the oxidative status of nestlings might underlie individual health and survival.

Dermatological conditions affecting the beak, claws, and feet of captive avian species

Captive avian species are presented for veterinary care for a variety of conditions and clinical signs. Although many of these presented birds seek veterinary care for other causes, some of these presentations involve dermatologic conditions that involve the beak, claws, and feet. A variety of presentations commonly seen include trauma to the beak, claws, and/or feet; leg-band injuries, pododermatitis, infectious causes, and beak growth abnormalities. Other less common presentations include thermal burns to the feet, self-mutilation of the feet, tumors of the feet and claws, and avian gout.

Cloacal fibrosarcoma in a canary (Serinus canaria)

A 1-year-old, male canary (Serinus canaria) with a history of an enlarged abdomen of several days duration died acutely and was submitted for necropsy. Results revealed a yellow to tan hard mass, 2 cm in diameter, adherent to the cloacal wall. Histologically, the mass was composed of interlacing bundles of pleomorphic spindle cells with numerous and bizarre mitotic figures. Neoplastic cells were positive for vimentin and negative for desmin and actin and showed ultrastructural features (dilated stacks of rough endoplasmic reticulum, intermediate filaments, rare collagen secretion granules, lack of external lamina) typical of fibroblasts. Based on these results, the diagnosis was cloacal fibrosarcoma, previously not reported in canaries.

A multiplex PCR for detection of poxvirus and papillomavirus in cutaneous warts from live birds and museum skins

Viral cutaneous lesions are frequent in some bird populations, though we are generally ignorant of the causal agent. In some instances, they represent a threat to livestock and wildlife health. We present here a multiplex PCR which detects and distinguishes infection by two such agents, avipoxviruses and papillomaviruses, in avian hosts. We assayed biopsies and superficial skin swabs from field and preserved museum skin specimens. Ninety-three percent of samples from symptomatic specimens tested positive for the presence of avipox (n = 23) or papillomavirus (n = 5). Sixteen and five sequences, corresponding to the P4b and L1 genes, were obtained from avipox and papillomavirus, respectively. One museum specimen, of Fringilla coelebs (chaffinch), was apparently infected with both viruses. Although papillomavirus sequences proved identical to previously published sequences, four novel avipox sequences were generated and used to build a neighbor-joining phylogenetic tree. Our tree recovered a similar topology to that of several recent authors; however, we also propose here two new minor avipox clades (B1b and B3). This multiplex PCR technique shows improved sensitivity compared to other avipox and papillomavirus assays, is able to detect a wide range of avipox and papillomavirus types (it amplifies all three avian-derived papillomavirus genera described thus far and sequences from both major avipox clades), and was even able to detect ancient viral DNA contained in museum specimens of greater than 75 years antiquity for both viruses.

A review of DNA viral infections in psittacine birds

To date, several DNA viral infections have been reported in psittacine birds. Psittacine beak and feather disease (PBFD) is characterized by symmetric feather dystrophy and loss and development of beak deformities. PBFD is caused by beak and feather virus, which belongs to the Circoviridae, and is the most important infection in psittacine birds worldwide. Avian polyomavirus infection causes acute death, abdominal distention, and feather abnormalities. Pacheco's disease (PD), which is caused by psittacid herpesvirus type 1, is an acute lethal disease without a prodrome. Psittacine adenovirus infections are described as having a clinical progression similar to PD. The clinical changes in psittacine poxvirus-infected birds include serious ocular discharge, rhinitis, and conjunctivitis, followed by the appearance of ulcerations on the medial canthi of the eyes. Internal papillomatosis of parrots (IPP) is a tumor disease characterized by progressive development of papillomas in the oral and cloacal mucosa. IPP has been suggested to caused by papillomavirus or herpesvirus. However, information about these diseases is limited. Here we review the etiology, clinical features, pathology, epidemiology, and diagnosis of these DNA viruses.

Tissue distribution of psittacid herpesviruses in latently infected parrots, repeated sampling of latently infected parrots and prevalence of latency in parrots submitted for necropsy

Psittacid herpesvirus-1 (PsHV-1) is the cause of an acute fatal disease in parrots and is implicated as the cause of papillomatous lesions of the digestive tract. Not all infections cause disease and some parrots are infected asymptomatically. Latently infected parrots are potential sources for virus dissemination. Tissues from parrots that died spontaneously with a history of coming from flocks where a PsHV-1 outbreak had occurred were examined for PsHV-1 DNA. Fourteen of 16 parrots examined were infected with at least 1 variant of PsHV-1; of these 13 (93%) had viral DNA in either or both the oral and cloacal mucosa, suggesting that most latently infected parrots could be detected by sampling these sites. Nine of 9 parrots shown to be infected 5 years prior to this study were positive again on repeat sampling and were infected with the same virus genotype. Opportunistic sampling of parrots submitted for diagnostic necropsy indicated that the prevalence of PsHV-1 in parrots in the sampled population was approximately 9.3%. PsHV-1 genotypes 1, 2, and 3 were found in these birds, but genotype 4 was not. Six necropsy specimens were found to be infected with two PsHV-1 genotypes and it was concluded that infection with one serotype did not protect against infection with another. Psittacid herpesvirus 2 (PsHV-2) was identified in 4 African grey parrots and a blue and gold macaw. Prior to this study PsHV-2 had only been found in African grey parrots.

Respiratory herpesvirus infection in two Indian Ringneck parakeets

A flock of Indian Ringneck parakeets ( Psittacula krameri manillensis) was imported to the United States from Australia. Soon after, 1 parakeet suddenly died, and a second parakeet died after a 2-day course of illness, which consisted of anorexia, lethargy, emaciation, and dyspnea. At necropsy, the affected birds had diffuse consolidation and red discoloration of the lungs, as well as thickened, congested air sacs. The microscopic examination revealed multifocal, necrotizing bronchitis, parabronchitis, and interstitial pneumonia. The lumen of the affected airways contained numerous, large syncytial cells with up to 15 nuclei. The nuclei of these syncytial cells often contained large, eosinophilic inclusion bodies, consistent with herpesvirus. The epithelium of the trachea and air sacs was hypertrophied and contained syncytial cells with intranuclear inclusion bodies similar to the bronchi. In addition, a few intranuclear inclusion bodies were also present in the epithelial cells that line the air capillaries. On ultrastructural examination, the nuclei of degenerating epithelial cells contained clusters of viral nucleocapsid proteins and unenveloped, icosahedral, viral particles that were approximately 90 nm in diameter. In addition, some epithelial cells contained clusters of enveloped viral particles approximately 105 nm in diameter, within the cytocavitary network. These lesions are characteristic of those caused by respiratory herpesvirus of parakeets.

Experimental Infection of Attwater's/Greater Prairie Chicken Hybrids with the Reticuloendotheliosis Virus

Reticuloendotheliosis virus (REV), a common pathogen of poultry, has been associated with runting and neoplasia in an endangered subspecies of grouse, the Attwater's prairie chicken. The pathogenesis of REV infection was examined in experimentally infected prairie chickens. Three groups of four Attwater's/greater prairie chicken hybrids were infected intravenously with varying doses (tissue culture infective dose [TCID50], 200, 1000, and 5000) of a prairie chicken-isolated REV. A fourth group of four birds was not infected. Blood was collected prior to infection, and at various times up to 37 wk following infection. Peripheral blood mononuclear cells were examined for integrated proviral DNA by a single-amplification polymerase chain reaction (PCR) and nested PCR of a region within the pol gene. The nested PCR identified REV proviral DNA in all REV-inoculated birds by 2 wk postinfection and confirmed chronic infection throughout the study. With the exception of a bird that died from bacterial pneumonia 8 wk postinfection, neoplasia, resembling that seen in naturally occurring infections, was observed in all birds, even those receiving as little as 200 TCID50 of virus.

A novel psittacid herpesvirus found in African grey parrots (Psittacus erithacus erithacus)

DNA from a novel alphaherpesvirus was amplified from a cloacal papilloma, a cutaneous papilloma, and the normal cloacal mucosa of African grey parrots (Psittacus erithacus erithacus). Phylogenetically, the virus was most closely related to the psittacid herpesvirus, but demonstrated sufficient nucleotide and amino acid diversity to be considered a new alphaherpesvirus. It is proposed that the previously described psittacid herpesvirus be designated as psittacid herpesvirus 1 (PsHV-1), and this new species be classified as psittacid herpesvirus 2 (PsHV-2). It is speculated that PsHV-2 co-evolved with the African grey parrot and should therefore be present in these birds in the wild.

Varanid herpesvirus 1: a novel herpesvirus associated with proliferative stomatitis in green tree monitors (Varanus prasinus)

Stomatitis is a common problem in lizards, and the etiologies of stomatitis in lizards are not well understood. Four green tree monitor lizards (Varanus prasinus) from two different collections were evaluated because of proliferative stomatitis. Degenerate PCR primers targeting a conserved region of herpesvirus DNA-dependent DNA polymerase were used to amplify and sequence a product from gingival tissue of three of four lizards (cases 1, 3, and 4). DNA in situ hybridization of tissues from three lizards was positive for herpesvirus in the oral mucosa of all three lizards tested (cases 1-3) and the brain of two lizards (cases 1 and 3). Comparative sequence analysis suggests that this virus is a novel member of the subfamily alpha-herpesvirinae, and is here termed varanid herpesvirus 1.

Tumors of pet birds

Neoplastic diseases are becoming more than a postmortem diagnosis due to the increasing knowledge base and improving quality of avian medicine. The expectation for better health care demands a diagnosis, prognosis, and therapy options. However, the published information regarding prognosis and therapy of specific neoplasms remains limited in avian medicine. With each case report or study that provides this information, there is an improvement in the level of care we can offer our companion avian species. This review will cover some basic information about specific tumor types and will reference the more recent reports in the avian literature. It is not intended to be all encompassing.