Severe leukopenia and liver necrosis in young African grey parrots (Psittacus erithacus erithacus) infected with psittacine circovirus

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 (p sittacine 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 live r necrosis in 11 of 14 birds and secondary bacterial or fungal infections i n 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 resembli ng circovirus. DNA in situ hybridization of six liver tissue samples confir med the presence of PBFD virus and excluded the presence of avian polyomavi rus. Our findings suggest that a specific presentation of peracute PBFD vir al infection, characterized by severe leukopenia, anemia, or pancytopenia a nd liver necrosis in the absence of feather and beak abnormalities, may occ ur in young African grey parrots.