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.