Occurrence of Pacheco’s Disease and Polyomavirus in Captive Psittacines from Brazil
Pacheco’s disease is caused by a herpesvirus and was first reported in Brazil in 1929.2 Clinical signs in psittacines include depression, diarrhea, regurgitation, neurological symptoms, and death. Another viral disease of psittacines, polyomavirus, is associated with depression, regurgitation, diarrhea, and subcutaneous hemorrhages.1,3,4 Although widely described in the literature, there are no reports of polyomavirus occurring in Brazil.
A blue-fronted Amazon parrot (Amazona aestiva), living in a zoo for some months, was euthanized for a progressive ocular mass in the right cranial periocular region. The mass did not respond to surgical removal. Macroscopic postmortem findings included severe hepatomegaly and splenomegaly. Histologic examination revealed the mass to be lymphoma-like, characterized by an anaplastic lymphoid-like cell. Similar infiltrates were observed in liver, spleen, and kidney. Acidophilic round structures, compatible with intranuclear inclusions, were also identified on histologic exam.
A ring-necked parakeet (Psittacula krameri) presented moribund 2 days after the owners acquired it from a pet shop. Death occurred before antemortem testing or treatment could be performed. Significant postmortem findings included hepatomegaly and splenomegaly. Histologic examination showed a large number of structures compatible with acidophilic intranuclear bodies.
Samples from both cases were submitted for in situ hybridization, using specific probes for Pacheco’s disease herpesvirus and for psittacine polyomavirus. Results obtained from the blue-fronted Amazon parrot showed the presence of a herpesvirus. The role of this herpesvirus in the neoplastic process and possible immunosuppression effects are unclear. Results from the ring-necked parakeet showed the presence of both a herpesvirus and a polyomavirus in the liver and spleen. The polyomavirus was responsible for most of the inclusion bodies observed and may represent the cause of death in this animal.
Following first report of this disease in Brazil in 1929, there have been no further reports of Pacheco’s disease. Laboratories that perform diagnostic testing to confirm Pacheco’s disease and polyomavirus infections are currently not available in Brazil. However, there are many psittacines in Brazil succumbing to hepatic disease without a definitive diagnosis. The authors believe that the mortality rate in psittacines from Pacheco’s disease and polyomavirus in Brazil is high, but the diagnostic tests are not available to confirm this theory.
This project was financially supported by a São Paulo Governmental Foundation (Fundação de Amparo a Pesquisa de São Paulo-FAPESP/SP).
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