Study on detection of viral DNA of the agents causing psittacine beak and feather disease and budgerigar fledgling disease in different psittacine species

In this study, certain aspects of psittacine beak and feather disease and budgerigar fledgling disease were investigated to gather information about the distribution and the clinical manifestation of the diseases in patients of the “Klinik für Vögel der LMU München”. Furthermore different organ samples were compared for their reliability of routine post mortem PCR-diagnoses of peracute PBFD in young african grey parrots. Regarding intra vitam detection of the aetiological agents of both diseases (BFDV and BFPyV), following observations were made: while in birds with physiological plumage, DNA of neither virus could be detected (BFDV: n = 79; BFPyV: n = 47), birds with feather disorders were regularly BFDV (18.2 %) and BFPyV (10.7 %) positive. In psittacines with feathering disorders an BFPyV-infection was only seen in budgerigars. The six affected budgerigars show acute loss of flight and tail feathers. In two birds a concurrent infection of BFPyV and BFDV could be detected and in one of the two birds a deformation of feathers could be seen. Characteristic feather disorders, as discribed for chronic PBFD, like constriction in feather sheats, remaining feather sleeves, discolouration as well as hemorrhages in the feather shaft, were only present in nine of the 24 BFDV-positive birds. The clinical signs of the remaining 15 BFDV-infected birds were only feather loss and feather picking. In contrast to BFPyV-infection, which could only be detected in budgerigars, the BFDV positive birds belong to different species of the order Psittaciformes. The testing of intra vitam samples showed, that in four of the BFDV-positive birds viral DNA could not be detected in all samples tested (2 x cloacal swab, 1 x blood, 1 x blood and cloacal swab). To increase the reliability of intra vitam diagnosis all three samples should be taken for virus detection. Within the group of birds presented for necropsy, the share of BFDV- and BFPyVpositive birds was even higher (25.5 % and 21.9 %) as in birds with feather disorders. In these birds a BFPyV-infection could be demonstrated in samples of seven birds of different species under the age of one year. Besides one budgerigar, who died of a streptococcus septicemia, all 13 BFDV-positive birds, who died with physiological plumage, were young african grey parrots. By testing DNA dilutions of different organ samples (skin-with-feather, spleen, bursa of Fabricius and liver) of young grey parrots suffering from peracute PBFD, an infection could be proven in 29 of 34 birds. In positive birds viral DNA of BFDV could be detected in all organ samples except for three single samples (2 x bursa of Fabricius and 1 x liver). But using undiluted isolated DNA, a great part of the spleen- (19 of 28) and bursa of Fabricius-samples (13 of 25) and a smaller part of liver- (6 of 28) and skin-with-feather-samples (3 of 29) gave a negative result Because of the high number of false negative PCR-tests the labarotories need to establish reliable internal controls PCR-diagnostic. Both viral infections appear regularly in our patients: in birds with feather disorders, as well as in young birds suffering from a lethal infection.