Pacheco's Disease Research Articles

Neck Kaposiform haemangioendothelioma in a Fischer’s lovebird (Agapornis fischeri)

A six-year-old female Fischer's lovebird (Agapornis fischeri) presented at necropsy with a cutaneous mass on the neck, 3.5cm in diameter, yielding and with blood content. Histopathological findings showed a neoplasm characterized by proliferation of vascular endothelial cells. The histology of the mass revealed a multinodular, focally infiltrating tumor. Deeper dermal nodules were made of spindle cells forming vascular slits reminiscent of the histology seen in Kaposi's sarcoma (KS). More superficially located dermal nodules consisted of small blood vessels, with histology resembling capillary hemangioma. The spindle cells and capillaries were strongly positive for Vimentin, endothelial cell marker CD31, and negative for sarcomeric α-smooth muscle actin (α-SMA). Intravascular platelet trapping and Periodic acid-Schiff (PAS)-positive hyaline globules were also observed. Differential diagnosis included Kaposi's sarcoma, capillary haemangioma, spindle cell haemangioendothelioma, and epithelioid haemangioendothelioma. Based on morphological and immunohistochemical findings, the tumor was diagnosed as a cutaneous Kaposiform haemangioendothelioma (KHE), a rare, low-grade malignant vascular neoplasm. Other organs showed no abnormalities. PCR amplifications, conducted using Kaposi's sarcoma-associated herpesvirus (KSHV)-specific primers and degenerate sets of primers designed to detect and characterize members of the Herpesviridae, on DNA extracted from tumor tissue and from whole blood failed to amplify any KSHV-related sequence. Moreover, no specific signal was obtained using primers for detection of psittacine herpesvirus, known to be linked to Pacheco's disease in parrots. To the best of our knowledge, this unusual case is the third report of KHE in a non-human animal species, the first described in a bird.

A novel herpesvirus associated with respiratory disease in Bourke's parrots (Neopsephotus bourkii)

A novel herpesvirus infection in nine Bourke's parrots (Neopsephotus bourkii, formerly Neophema bourkii) housed in an outdoor aviary comprised of multiple species of birds was diagnosed based on histopathology, electron microscopy and polymerase chain reaction (PCR). Clinical signs in the parrots included anorexia, ruffled feathers, depression, loss of weight and respiratory distress. The most common gross lesions were moderately congested and oedematous lungs and a mild fibrinous exudate in the air sacs and lumen of the trachea. Histological examination revealed mild to severe bronchopneumonia and airsacculitis with syncytial cells containing eosinophilic intranuclear inclusion bodies in most birds. Other less frequent changes included tracheitis, syringitis, sinusitis, rhinitis, otitis media and conjunctivitis. Attempts to culture the virus in chicken embryos and chicken embryo liver cells were unsuccessful. Examination by transmission electron microscopy of syncytial cells from the lungs of two birds revealed intranuclear virus particles typical of the family Herpesviridae. DNA from a novel herpesvirus was amplified from lung tissue by PCR using degenerate primers derived from conserved avian herpesvirus sequences. The virus belongs in the genus Iltovirus of the Alphaherpesvirinae subfamily. It is not closely related to Psittacid herpesvirus 1 that causes Pacheco's disease but does group phylogenetically with a clade of herpesviruses that cause respiratory disease in a number of avian species. The proposed name for this herpesvirus is Psittacid herpesvirus 3.

Molecular Genetic and Pathogenic Characterization of Psittacid Herpesvirus Type 1 Isolated from a Captive Galah (Eolophus roseicapillus) in Japan

Psittacid herpesvirus type 1 (PsHV-1) was isolated from a captive galah (Eolophus roseicapillus) in Japan that was suspected of having Pacheco's disease (PD), an acute fatal disease in psittacine birds. PsHV-1 has been classified into four genotypes based on the UL16 gene sequence. In the present study, we investigated the genetic and pathogenic characteristics of the isolated virus, FOY-1, compared with a reference strain, RSL-1. The FOY-1 strain was classified into PsHV-1 genotype 2. The FOY-1 strain was found to be less pathogenic to budgerigars than RSL-1, which was classified as genotype 4 in an in vivo study. This is the first report regarding the classification of originally isolated PsHV-1 in Japan and its characterization by animal infection experiment.

オウム嘴羽病とパチェコ氏病を併発したセキセイインコの1例及び感染実験

オウム嘴羽病とパチェコ氏病を併発したセキセイインコの1例及び感染実験

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.

Mycobacterium aviumsubsp.hominissuisInfection in a Pet Parrot

To the Editor: Tuberculosis is a chronic wasting disease in domestic birds (especially hens) and free-ranging birds worldwide (1). Most mycobacterial infections in birds are caused by Mycobacterium avium subsp. avium (mainly domestic birds) or by M. genavense (especially pet birds). Nontuberculous (potentially pathogenic) mycobacteria (i.e., M. fortuitum, M. gordonae, and M. nonchromogenicum) occasionally have been isolated from necropsied pet birds (2). Because potentially pathogenic mycobacteria also are increasingly problematic in immunocompromised human patients, they merit special attention. M. avium subsp. hominissuis can infect humans, especially immunocompromised persons. M. avium subsp. hominissuis infections have been documented in pigs and cattle (3) and rarely in dogs (4), birds (5), and other animals.

Reovirus infections associated with high mortality in psittaciformes in The Netherlands

In The Netherlands between January 2002 and December 2004, numerous psittaciformes died showing severe splenomegaly and hepatomegaly with multifocal acute necrosis. At the start of the outbreaks mostly parakeets were affected, but later larger parrots were also involved. Seventy-eight birds showed the same features and six were examined completely, including a virological examination. Tests for polyomavirus, Pacheco's disease (herpesvirus) and circovirus psittacine beak and feather disease (PBFD) viruses and Chlamydophila psittaci were carried out. All results were negative, except for two cases of circovirus infection. Many concurrent bacterial and parasitic infections were seen. Immunohistochemistry revealed reovirus antigen in intralesional mononuclear cells, and reovirus-like particles could be observed by negative contrast electron microscopy. A reovirus was grown and the isolates reacted with polyclonal reovirus antiserum but did not react with monoclonal antibodies against chicken reovirus. The virus was therefore considered a psittacine reovirus. Because reoviruses were seen consistently, they seemed to be the most probable cause of the outbreaks. Climate, the introduction of new birds and the transportation of birds might be other factors involved in the disease seen in The Netherlands. No regional influence could be seen; therefore, we suggested that the virus might be widespread and carriers could be a source of re-introduction.

Endocrine Pancreatic Insufficiency Secondary to Chronic Herpesvirus Pancreatitis in a Cockatiel (Nymphicus hollandicus)

A cockatiel (Nymphicus hollandicus) examined because of weight loss, polydipsia, and polyuria was diagnosed with diabetes mellitus based on the presence of glucosuria and marked hyperglycemia. Medical attempts to manage the diabetes mellitus were unsuccessful, and the bird was euthanatized. Histopathologic examination of the pancreas revealed a chronic active pancreatitis with herpesviral inclusions in many of the pancreatic acinar and duct cells. Psittacid herpesvirus-1 (PsHV-1) DNA was amplified from the lesion by polymerase chain reaction. Sequencing of the amplicon showed it to be the genotype 1 variant, which is most commonly associated with Pacheco's disease, an acute rapidly fatal systemic infection. The findings in this case suggest that the PsHV-1 genotype may also cause a localized disease of the pancreas. Infection with this virus should be considered as a differential diagnosis in birds with pancreatitis with or without diabetes mellitus.

Pacheco’s disease in a Hungarian zoo bird population: A case report

An epizootic of Pacheco's disease is reported from a zoo bird population. The infection was introduced by wild-captured Patagonian conures (Cyanoliseus patagonus) despite 61 days of quarantine. The disease affected several parrot species and, interestingly, three out of seven bearded barbets (Lybius dubius). The mortality rate was 30.93%. Autopsy revealed abdominal hyperaemia with liver haemorrhages and, in less rapid cases, yellowish discoloration and fragility of the liver. Death was caused by the collapse of circulation. Histopathology demonstrated liver cell necrosis, disintegration of the lobular structure, and a few intranuclear inclusion bodies. Icosahedral virions were detected by electron microscopy. The virus was isolated in the allantoic cavity of embryonated chicken eggs as well as in chicken embryo fibroblast cell culture. A 281-bp-long fragment of psittacid herpesvirus DNA was detected by PCR in cell culture material and liver samples of the affected birds. To our knowledge this is the first report of Pacheco's disease in bearded barbets as well as the first occurrence of Pacheco's disease in Hungary.

Psittacid Herpesvirus 1 and Infectious Laryngotracheitis Virus: Comparative Genome Sequence Analysis of Two Avian Alphaherpesviruses

Psittacid herpesvirus 1 (PsHV-1) is the causative agent of Pacheco's disease, an acute, highly contagious, and potentially lethal respiratory herpesvirus infection in psittacine birds, while infectious laryngotracheitis virus (ILTV) is a highly contagious and economically significant avian herpesvirus which is responsible for an acute respiratory disease limited to galliform birds. The complete genome sequence of PsHV-1 has been determined and compared to the ILTV sequence, assembled from published data. The PsHV-1 and ILTV genomes exhibit similar structural characteristics and are 163,025 bp and 148,665 bp in length, respectively. The PsHV-1 genome contains 73 predicted open reading frames (ORFs), while the ILTV genome contains 77 predicted ORFs. Both genomes contain an inversion in the unique long region similar to that observed in pseudorabies virus. PsHV-1 is closely related to ILTV, and it is proposed that it be assigned to the Iltovirus genus. These two avian herpesviruses represent a phylogenetically unique clade of alphaherpesviruses that are distinct from the Marek's disease-like viruses (Mardivirus). The determination of the complete genomic nucleotide sequences of PsHV-1 and ILTV provides a tool for further comparative and functional analysis of this unique class of avian alphaherpesviruses.

Multifocal Sialoceles and Sialoliths in a Yellow-naped Amazon Parrot (Amazona ochrocephala auropalliata) With Chronic Ptyalism

A yellow-naped Amazon parrot (Amazona ochrocephala auropalliata) was presented with a 1-year history of feather-destructive behavior with an incidental 14-year history of ptyalism. Palpation, radiographs, fluoroscopy, and biopsy confirmed a diagnosis of multiple sialoceles and sialoliths throughout the cervical region. Treatment for ptyalism was not necessary in this parrot; however, treatment in other species generally involves surgical resection or medical treatment with anticholinergics or botulinum toxin A injections. Clinical signs associated with both the presence of sialoceles and feather-destructive behavior improved briefly with changes in husbandry and medical treatment including antibiotics and anti-inflammatory medications. There have been few reports of this lesion in avian species, except for occasional reports in pigeons where the underlying cause is thought to be either hypovitaminosis A or herpesviral infection. This parrot was on a nutritionally adequate diet and had a negative antibody titer for Pacheco's disease, and no underlying cause was identified.

Genetic characterization of a herpesvirus isolate from a superb starling (Lamprotornis superbus) as a psittacid herpesvirus genotype 1.

Four genotypes of the psittacid herpesvirus (PsHV) cause Pacheco disease in parrots. Viruses that are serologically cross-reactive to the PsHVs have also been isolated from passerine species. DNA was amplified from a herpesvirus isolated from a superb starling (Lamprotornis superbus) with PsHV-specific primers and polymerase chain reaction. A comparison of the partial sequence of the UL 16 gene from this herpesvirus with sequences from viruses of known PsHV genotypes showed that the herpesvirus from the superb starling was a PsHV genotype 1 virus. This finding expands the range of birds that are known to be susceptible to PsHV genotype 1 infections and suggests that PsHVs should be considered as a differential in passerines with herpesvirus infections.

Molecular phylogeny of the psittacid herpesviruses causing Pacheco's disease: correlation of genotype with phenotypic expression.

Fragments of 419 bp of the UL16 open reading frame from 73 psittacid herpesviruses (PsHVs) from the United States and Europe were sequenced. All viruses caused Pacheco's disease, and serotypes of the European isolates were known. A phylogenetic tree derived from these sequences demonstrated that the PsHVs that cause Pacheco's disease comprised four major genotypes, with each genotype including between two and four variants. With the exception of two viruses, the serotypes of the virus isolates could be predicted by the genotypes. Genotypes 1 and 4 corresponded to serotype 1 isolates, genotype 2 corresponded to serotype 2 isolates, and genotype 3 corresponded to serotype 3 isolates. The single serotype 4 virus mapped to genotype 4. DNA from a virus with a unique serotype could not be amplified with primers that amplified DNA from all other PsHVs, and its classification remains unknown. Viruses representing all four genotypes were found in both the United States and Europe, and it was therefore predicted that serotypes 1, 2, and 3 were present in the United States. Serotype 4 was represented by a single European isolate that could not be genetically distinguished from serotype 1 viruses; therefore, the presence of serotype 4 in the United States could not be predicted. Viruses of genotype 4 were found to be the most commonly associated with Pacheco's disease in macaws and conures and were least likely to be isolated in chicken embryo fibroblasts in the United States. All four genotypes caused deaths in Amazon parrots, but genotype 4 was associated with Pacheco's disease only in Amazons in Europe. Genotypes 2, 3, and 4, but not 1, were found in African grey parrots. Although parrots from the Pacific distribution represent a relatively small percentage of the total number of birds with Pacheco's disease, all four genotypes were found to cause disease in these species.

Virus neutralization assays used in exotic bird medicine

This article describes virus neutralizing assays (VNs) used to detect antibody produced in response to avian polyomavirus and psittacid herpesvirus infection (Pacheco's disease virus). A detailed discussion of the interpretation of these assays and their use in avian medicine is provided.

Differentiation of psittacine herpesvirus field isolates by restriction endonuclease analysis

Thirty-one viruses were isolated from 15 different psittacine species. They were all identified as herpesviruses on the basis of chloroform sensitivity, inhibition of replication in cell cultures by 5-iodo-2'-deoxyuridine and morphology by electron microscopy. DNA from all 31 field isolates of psittacine herpesviruses (PsHV) was analysed by cleavage with restriction endonucleases EcoRI, PstI, and BglII. Using this technique, 12 different restriction patterns were recognizable. In previous work, we have differentiated PsHV strains according to their serological interrelationships. Restriction endonuclease profiles confirmed the results of conventional serogrouping but additional differences were observed among the five established serological subtypes. Using this method, it was possible to demonstrate a spontaneous reinfection of parrots in an aviary with a serologically and genetically different PsHV strain 4 years after the first outbreak of Pacheco's parrot disease (PPD). The results of this study reaffirm that antigenetically and genetically different PsHV exist and can cause PPD.

Detection and heterogeneity of herpesviruses causing Pacheco's disease in parrots.

Pacheco's disease (PD) is a common, often fatal, disease of parrots. We cloned a virus isolate from a parrot that had characteristic lesions of PD. Three viral clones were partially sequenced, demonstrating that this virus was an alphaherpesvirus most closely related to the gallid herpesvirus 1. Five primer sets were developed from these sequences. The primer sets were used with PCR to screen tissues or tissue culture media suspected to contain viruses from 54 outbreaks of PD. The primer sets amplified DNA from all but one sample. Ten amplification patterns were detected, indicating that PD is caused by a genetically heterogeneous population of viruses. A single genetic variant (psittacid herpesvirus variant 1) amplified with all primer sets and was the most common virus variant (62.7%). A single primer set (23F) amplified DNA from all of the positive samples, suggesting that PCR could be used as a rapid postmortem assay for these viruses. PCR was found to be significantly more sensitive than tissue culture for the detection of psittacid herpesviruses.

A review of the most common viruses affecting Psittaciformes

Four of the most common viral infections affecting psittacine birds have been studied in detail: (1) avian polyomavirus, (2) proventricular dilatation disease (PDD), (3) Pacheco's disease and (4) psittacine beak and feather disease (PBFD). The Psittacine Disease Research Group, University of Georgia, has been actively involved in this research. Proventricular dilatation disease has been reported in more than 50 psittacine species and in species in other families, while PBFD affects over 40 psittacine species. The acute and chronic clinical characteristics of the diseases, pathological features, diagnosis, and transmission prevention and control, including vaccination, are described. The vaccine for avian polyomavirus is safe and effective in captive birds, and, when used in high-risk situations, vaccination against Pacheco's disease (a psittacine herpesvirus) can prevent high mortality. A safe vaccine for PBFD is being evaluated. Specific tests for viral nucleic acid (DNA probe tests) for avian polyomavirus and PBFD virus, and anti-virus antibody assays for avian polyomavirus and Pacheco's disease have been developed which will facilitate the diagnosis and monitoring of disease. The benefits and limitations of screening psittacines for disease are also discussed.

Quantification of the herpesvirus content in various tissues and organs, and associated post mortem lesions of psittacine birds which died during an epornithic of pacheco's parrot disease (PPD)

This paper reports on the viral content of up to 52 tissue and organ samples of 18 individual large psittacines which died during an epornithic of Pacheco's parrot disease (PPD) caused by psittacid herpesvirus 1 (PsHV1). Associated clinical signs and pathological lesions are described. The large spectrum of samples found to be positive for PsHVl suggests that birds succumb to PPD during viraemia. Tissues and organs from which the virus could be isolated included the integument and associated structures, the muscular, respiratory and circulatory system, bone marrow, the nervous system, thyroid and adrenal glands, spleen and liver, the urogenital tract and the gastro‐intestinal tract. Nevertheless, individual and organ (but not species)‐specific variation does occur. Virus isolation appears to be most promising from the respiratory, vascular and nervous system and the liver. Highest titres were obtained from heart blood and liver (up to 7.6 log10/g tissue), airsac, Nervus vagus and pulp and quill of pin feathers. Pin feathers may therefore be suitable for in‐vivo diagnosis. In contrast, HV could not be isolated from any of the feather vanes examined. For the most part, post mortem lesions do not reflect the organ pattern found to be most permissive for virus replication as judged by the success of virus isolation and virus titres. A closer quantitative correlation is indicated for the lungs, spleen and liver, only. Corresponding findings as to frequency of gross pathological lesions and virus quantification appear to be restricted to the liver. In accordance with clinical observations and experimental findings, tissue virus content indicates that horizontal spread of herpesviruses is mediated by cloacal contents or secretions from the respiratory system.

A serologic survey for avian polyomavirus and Pacheco's disease virus in Australian cockatoos

Sera collected from wild and captive Australian cockatoos and other psittacine species (n = 411) were tested for antibodies to avian polyomavirus (APV) and Pacheco's disease virus (PDV). Of 144 wild sulphur‐crested cockatoos (Cacatua galerita) sampled at three regions in New South Wales (NSW) 96 (64.4%) birds had positive (≥ 1:32) neutralizing antibody titres to avian polyomavirus (range 1:32–1:2048). Two of 17 wild long‐billed corellas (Cacatua tenuirostris) were also APV‐antibody positive. However, no samples from 107 wild galahs (Eolophus roseicapillus) were positive for neutralizing antibody to APV. Sera were also collected from captive psittacine bird flocks from NSW, Tasmania, Victoria, and Western Australia. In a mixed aviary of cockatoos and lorikeets, APV antibody was detected in sera from sulphur‐crested cockatoos, Major Mitchell's cockatoos (Cacatua leadbeateri), a white‐tailed black cockatoo (Calyptorhynchus baudinii latirostris), a red‐tailed black cockatoo (Calyptorhynchus magnificus) a single galah, a rainbow lorikeet (Trichoglossus haematodus), and a scaley‐breasted lorikeet (Trichoglossus chlorolepidotus). All 411 wild and captive birds were negative for the presence of neutralizing antibody to PDV. These results indicate that wild sulphur‐crested cockatoos in NSW are enzootically infected with avian polyomavirus and that the sampled populations are free of Pacheco's disease.

Diagnosis of Avian Adenovirus Infections Using DNA in situ Hybridization

Three DNA oligonucleotide probes designated FN-23, FN-48, and FN-96 were evaluated for the diagnosis of aviadenovirus infections by DNA in situ hybridization. Paraffin-embedded tissues were obtained from birds with confirmed adenovirus infection, birds with putative adenovirus infections, and birds with intranuclear inclusions caused by herpesvirus and polyomavirus. In birds with confirmed adenovirus infection, probes FN-23 and FN-96 identified 78% and 72% of diseased individuals, respectively. Only probe FN-48 detected chickens with group II adenovirus infection. In birds with putative adenovirus infection, the DNA probes confirmed aviadenovirus infections in 76% of the population. Probes FN-23, FN-96, and FN-48 detected 85%, 74%, and 18% of adenovirus-infected birds, respectively. None of the DNA probes cross-hybridized with tissues from polyomavirus-infected psittaciform birds or with tissues from a chicken with infectious laryngotracheitis. In contrast, probe FN-23 did cross-hybridize to herpesvirus-infected tissues from two of eight psittaciform birds with Pacheco's parrot disease. Probes FN-48 and FN-96 did not react with these tissues.