Psittacid herpesvirus 3 infection in the eclectus parrot (Eclectus roratus) in Australia

A Survey of Diseases in Different Species of Wild, Captive, and Illegally Traded Birds in Brazil

Native and exotic avian species can act as reservoirs of pathogens, including bacteria and viruses, with conservation and public health implications. A retrospective study on the diagnosis and frequency of diseases in wild and exotic avian species was conducted. The occurrence of particular diseases was associated with the type of captivity or the bird's origin. The investigation included macroscopic and microscopic descriptions and the molecular determination of the causative agent(s). Additional immunohistochemical (IHC) analysis, PCR, and genetic sequencing were conducted. A total of 243 cases were compiled for the study, mainly consisting of native wild species (39.1%) obtained from illegal trade. Primary infectious diseases, mainly parasitic (18.1%) and viral (17.7%), were the most common, although coinfections were substantial (18.1%) in birds rescued from trafficking. Fractures and neoplasms accounted for 3.7% and 3.3% of the cases, respectively. Parasitic and viral diseases were the most common in both exotic and wild birds. Chlamydia psittaci, a lethal and zoonotic bacterium, was an important cause of death, especially in native Psittaciformes. The recent detection of Psittacid alphaherpesvirus 5 (PsAHV 5) in exotic psittacines and the diagnosis of coinfections in trafficked birds highlight the importance of monitoring avian health to control potential pathogens that may endanger conservation efforts.

Naturally occurring psittacid alphaherpesvirus 3 and probable adenovirus coinfection in an Indian ringneck parakeet in the United States

Psittacid alphaherpesvirus 3 (PsAHV-3) is a rarely reported virus that has been associated with pneumonia in psittacine birds. A 5-mo-old Indian ringneck parakeet (syn. rose-ringed parakeet; Psittacula krameri) was euthanized after developing torticollis and lethargy. Postmortem examination of the parakeet revealed severe pneumonia with syncytial cells containing eosinophilic intranuclear inclusion bodies (INIBs) in the respiratory epithelium. Gene sequencing of total DNA extraction detected PsAHV-3 in the frozen lung. The pancreas had severe lytic necrosis, with the remaining parenchymal cells expanded by large basophilic INIBs. Electron microscopy of the pancreas revealed intranuclear paracrystalline arrays of viral particles morphologically resembling adenovirus. Although we found 3 PsAHV-3 cases in birds in a literature search, we found no cases with adenoviral coinfection.

Unexpected Pathogen Diversity Detected in Australian Avifauna Highlights Potential Biosecurity Challenges

Birds may act as hosts for numerous pathogens, including members of the family Chlamydiaceae, beak and feather disease virus (BFDV), avipoxviruses, Columbid alphaherpesvirus 1 (CoAHV1) and Psittacid alphaherpesvirus 1 (PsAHV1), all of which are a significant biosecurity concern in Australia. While Chlamydiaceae and BFDV have previously been detected in Australian avian taxa, the prevalence and host range of avipoxviruses, CoAHV1 and PsAHV1 in Australian birds remain undetermined. To better understand the occurrence of these pathogens, we screened 486 wild birds (kingfisher, parrot, pigeon and raptor species) presented to two wildlife hospitals between May 2019 and December 2021. Utilising various qPCR assays, we detected PsAHV1 for the first time in wild Australian birds (37/486; 7.61%), in addition to BFDV (163/468; 33.54%), Chlamydiaceae (98/468; 20.16%), avipoxviruses (46/486; 9.47%) and CoAHV1 (43/486; 8.85%). Phylogenetic analysis revealed that BFDV sequences detected from birds in this study cluster within two predominant superclades, infecting both psittacine and non-psittacine species. However, BFDV disease manifestation was only observed in psittacine species. All Avipoxvirus sequences clustered together and were identical to other global reference strains. Similarly, PsAHV1 sequences from this study were detected from a series of novel hosts (apart from psittacine species) and identical to sequences detected from Brazilian psittacine species, raising significant biosecurity concerns, particularly for endangered parrot recovery programs. Overall, these results highlight the high pathogen diversity in wild Australian birds, the ecology of these pathogens in potential natural reservoirs, and the spillover potential of these pathogens into novel host species in which these agents cause disease.

Psittacid alphaherpesvirus 5 infection in Indian ringneck parakeets in southern California

Four Indian ringneck parakeets (Psittacula krameri; syn. ringneck parrots or rose-ringed parakeets) were submitted by 2 private owners for autopsy following a history of dyspnea and death. Gross findings were varied and included thickening of the left caudal thoracic air sac, white spots throughout the liver, mild dilation of the proventriculus, coelomic effusion, splenomegaly, and pulmonary congestion and edema. Microscopically, the submitted parakeets had significant lesions in the lower respiratory tract, including necrotizing bronchitis, parabronchitis, and interstitial pneumonia with numerous syncytia containing eosinophilic intranuclear inclusions. Electron microscopy of the lungs was compatible with a herpesviral infection and Psittacid alphaherpesvirus 5 (PsAHV5) was detected via PCR and sequencing. There has been inconsistent terminology used with Psittacid alphaherpesvirus 3 and PsAHV5; we attempt here to clarify the reported history of these viruses.

First detection of Psittacid alphaherpesvirus 5 and coinfection with beak and feather disease virus in naturally infected captive ringneck parakeets (Psittacula krameri) in Brazil

This study describes a case report in captive rose-ringed parakeets (Psittacula krameri) that developed clinical signs and eventually died after introducing new birds without quarantine. Bronchopneumonia and airsacculitis with syncytial cells associated with intranuclear inclusion bodies were found. Herpesvirus was detected in lungs and liver by PCR, and a nearly complete genome sequence of a Psittacid alphaherpesvirus 5 was obtained from the lung of a bird. Metagenomic analysis also identified beak and feather disease virus in the same samples. The study also highlights the importance of quarantine for avoiding the introduction of new diseases in captive aviaries.

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).

Psittacid herpesvirus 3 infection in rose-ringed parakeets in southern Brazil

We diagnosed disease caused by psittacid herpesvirus 3 (PsHV-3), a novel psittacid pathogen, in rose-ringed parakeets (Psittacula krameri) housed in an exotic psittacine breeding colony in southern Brazil. The disease affected several adult birds. Clinical signs included apathy, tachypnea, and wheezing. Four birds were autopsied, and sections of lungs and liver were examined histologically and by electron microscopy (EM), revealing pulmonary congestion, bronchopneumonia, or multifocal necrosis of tertiary bronchi, with syncytial cells and eosinophilic intranuclear inclusion bodies. Viral particles morphologically compatible with herpesviruses were observed by EM in lung sections. PCR with pan-herpesvirus primers performed on total DNA extracted from paraffinized tissue resulted in a 278-bp product. Sequencing of the amplicon revealed 93% nucleotide identity with a PsHV-3 sequence available in GenBank. Phylogenetic analysis grouped the obtained sequence with the only PsHV-3 DNA polymerase gene sequence available (GenBank accession JX028240) and separated the sequence from psittacid herpesviruses 1 and 2. The clinical, pathologic, and molecular findings support the association of PsHV-3 with pneumonia found in these rose-ringed parakeets in southern Brazil.

Molecular and microscopic characterisation of a novel pathogenic herpesvirus from Indian ringneck parrots (Psittacula krameri)

A high morbidity, high mortality disease process caused flock deaths in an Indian ringneck parrot (Psittacula krameri) aviary flock in Victoria, Australia. Affected birds were either found dead with no prior signs of illness, or showed clinical evidence of respiratory tract disease, with snicking, sneezing and dyspnoea present in affected birds. Necropsy examinations performed on representative birds, followed by cytological and histopathological examination, demonstrated lesions consistent with a herpesvirus bronchointerstitial pneumonia. Transmission electron microscopy analysis of lung tissue demonstrated typical herpesvirus virions measuring approximately 220 nm in diameter. Next generation sequencing of genomic DNA from lung tissue revealed a highly divergent novel Psittacid alphaherpesvirus of the genus Iltovirus. Iltoviruses have been previously reported to cause respiratory disease in a variety of avian species, but molecular characterisation of the viruses implicated has been lacking. This study presents the genome sequence of a novel avian herpesvirus species designated Psittacid alphaherpesvirus-5 (PsHV-5), providing an insight into the evolutionary relationships of the alphaherpesviruses.

Psittacid Adenovirus-2 infection in the critically endangered orange-bellied parrot (Neophema chrysogastor): A key threatening process or an example of a host-adapted virus?

Psittacid Adenovirus-2 (PsAdv-2) was identified in captive orange-bellied parrots (Neophema chrysogastor) during a multifactorial cluster of mortalities at the Adelaide Zoo, South Australia, and an outbreak of Pseudomonas aeruginosa septicaemia at the Tasmanian Department of Primary Industries, Parks, Water and Environment captive breeding facility, Taroona, Tasmania. This was the first time that an adenovirus had been identified in orange-bellied parrots and is the first report of PsAdv-2 in Australia. To investigate the status of PsAdv-2 in the captive population of orange-bellied parrots, 102 healthy birds from five breeding facilities were examined for the presence of PsAdv-2 DNA in droppings and/or cloacal swabs using a nested polymerase chain reaction assay. Additionally, eight birds released to the wild for the 2016 breeding season were similarly tested when they were recaptured prior to migration to be held in captivity for the winter. PsAdv-2 was identified in all breeding facilities as well as the birds recaptured from the wild. Prevalence of shedding ranged from 29.7 to 76.5%, demonstrating that PsAdv-2 is endemic in the captive population of orange-bellied parrots and that wild parrots may have been exposed to the virus. PsAdv-2 DNA was detected in both cloacal swabs and faeces of the orange-bellied parrots, but testing both samples from the same birds suggested that testing faeces would be more sensitive than cloacal swabs. PsAdv-2 was not found in other psittacine species housed in nearby aviaries at the Adelaide Zoo. The source of the infection in the orange-bellied parrots remains undetermined. In this study, PsAdv-2 prevalence of shedding was higher in adult birds as compared to birds less than one year old. Preliminary data also suggested a correlation between adenovirus shedding prevalence within the breeding collection and chick survival.