Severe Leukopenia and Liver Necrosis in Young African Grey Parrots (Psittacus erithacus erithacus) Infected with Psittacine Circovirus

Abstract

This paper describes the signs, clinical pathology, and postmortem findings in 14 young African grey parrots (Psittacus erithacus erithacus) that were naturally infected with psittacine beak and feather disease (PBFD) virus (psittacine circovirus). All but two of the parrots had severe leukopenia at clinical presentation. Two other parrots also had severe anemia. All birds died within 3 wk after presentation. Postmortem examination documented liver necrosis in 11 of 14 birds and secondary bacterial or fungal infections in 9 of 14 birds. Tests for Chlamydia psittaci, polyomavirus, and Salmonella sp. were negative. PBFD viral infection could be demonstrated in all birds by polymerase chain reaction. Supporting evidence of PBFD viral infection was gathered by histologic examination of the bursa of Fabricius, electron microscopy, and DNA in situ hybridization. Electron microscopic examination of both the bursa of Fabricius and liver revealed virus particles resembling circovirus. DNA in situ hybridization of six liver tissue samples confirmed the presence of PBFD virus and excluded the presence of avian polyomavirus. Our findings suggest that a specific presentation of peracute PBFD viral infection, characterized by severe leukopenia, anemia, or pancytopenia and liver necrosis in the absence of feather and beak abnormalities, may occur in young African grey parrots.

Molecular analysis and associated pathology of beak and feather disease virus isolated in Italy from young Congo African grey parrots (Psittacus erithacus) with an “atypical peracute form” of the disease

“…In addition, apoptotic caspase-1-positive and TUNEL-positive cells also showed concurrent positivity to BFDV staining without the typical botryoid and basophilic inclusion bodies. This particular clinical and post-mortem presentation of the disease is very similar to those reported by Schoemaker et al (2000) in young CAGPs.…”

“…Frequently, in birds up to 3 years of age, the disease begins with depression and lethargy followed by a chronic, progressive, bilateral and symmetrical feather dystrophy occasionally accompanied by beak deformity. Until now only peracute and acute forms have been described in nestling and fledgling parrots (Schoemaker et al, 2000;Doneley, 2003;Rahaus & Wolff, 2003;Raue et al, 2004). Here, death may occur suddenly, without evidence of feather dystrophy (peracute form) or with mild evidence of feather dystrophy (acute form).…”

Global genetic diversity and geographical and host-species distribution of beak and feather disease virus isolates

“…PBFD mainly affects young birds and is characterized by loss of feathers, abnormally shaped feathers and the overgrowth and irregularity of the surface of the beak. The disease has been associated with immunosuppression and most birds with PBFD die from a secondary bacterial and/or viral infection (Doneley, 2003;Pass & Perry, 1984;Ritchie et al, 1989;Schoemaker et al, 2000). Apart from the main clinical manifestations, peracute and subclinical infections have been described; the peracute infection affects young birds and beak and feather abnormalities are notably absent (Doneley, 2003;Rahaus & Wolff, 2003;Schoemaker et al, 2000).…”

Duplex Shuttle PCR for Differential Diagnosis of Budgerigar Fledgling Disease and Psittacine Beak and Feather Disease

“…APV has been identified by immunofluorescent antibody staining (8,22), in situ hybridization (27), electron microscopy (4-9, 12, 17), virus-neutralization test (23,39) and PCR (13,24). PBFDV has been identified by in situ hybridization (27), immunohistochemistry, hemagglutination and hemagglutination inhibition (26,30,31), electron microscopy (11,32,34,35), and PCR (14,28,40). PCR is a highly sensitive method and able to detect specific DNA sequences in a sample.…”