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 (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.