| |
History
Psittacine Beak and Feather Disease, also known as Psittacine Circovirus, is a viral
disease of parrots which affects the plumage, skin, and immune system. All psittacines
should be considered susceptible even though New World species (South American) seem
to be more resistent. Numerous flocks of wild Australian parrots have been infected
and it is estimated that up to 20% of wild cockatoos have PBFD.
Signs
Two forms of PBFD exist, acute (sudden onset) and chronic (long term). Acute PBFD
affects young hatchlings and causes feather abnormalities such as hemorrhage in the
quills, poorly formed contour feathers, shedding of feathers as well as general illness
and regurgitation. Chronic PBFD birds may be partially recovered acutely infected
PBFD birds. Chronically infected birds first develop a shiny beak and dirty plumage
due to decreased down production by the down feathers. Next, bloody quills will be
present on new feathers and later abnormally small and curled feathers develop. Skin
lesions may occur, such as pigmentation, ulcers, scaling and infections. Later in
advanced cases, the beak becomes soft and may literally rot away. At this point,
bacterial and fungal infections may also be present as secondary invaders.
Diagnosis
Clinical signs are often all that is needed for a diagnosis in advanced cases. Disease
is confirmed with a DNA blood test, which is the most accurate test available. The
test is very sensitive and specific for PBFD but false positives and negatives can
occur so positive birds should be retested in 90 days. Skin and feather biopsy is
still used to diagnose PBFD in birds in some instances.
Transmission
PBFD is spread by direct contact of affected birds and by spread of feather dust,
dander and fecal material. It may be spread from adults to offspring and may even
be contracted from a nest box which has been unused for many months or years. The
virus is very stable in the environment and is resistant to disinfectants.
Treatment
There is no cure for birds affected by PBFD, and chronic PBFD birds do not recover
from the disease. A few species such as budgies and lovebirds, and ocassionally and
adult parrot recently exposed, may recover from acute PBFD and may remain carriers.
Thus, all valuable parrots should be isolated from these species.
A few treatment modalities have been shown to have minimal success at best. Immunostimulants
have helped improve the quality of life of some infected birds but have not been
reported to cure them, as disease persists when the drugs are discontinued. Therefore,
treatments appear only to slow the progression of the disease.
A vaccine has been developed for PBFD but its release has been delayed in the United
States and may never occur at all since the disease can be controlled by testing
and elimination of positive birds. However, the vaccine is currently being tried
in Australia's wild and captive cockatoos. If it is ever released, it will most likely
be added to a Polyomavirus vaccine.
Control is best acheived by identifying carrier birds, isolation and maintaining
a closed aviary once PBFD is eliminated from the flock.
|
|
