A108 - Psittacine Beak and Feather Disease (PBFD)

Description:

Psittacine Beak and Feather Disease (PBFD) is a chronic disease characterized by feather dystrophy and loss, beak deformity and ultimately, death. The cause of PBFD is a newly discovered virus in the family Circoviridae. The disease probably originated in Australia and spread to other continents as a result of the shipment of birds for the pet bird trade. The disease has been reported in Australia, North America, Europe and Asia. Most species of parrots are susceptible to the virus however the species most commonly affected are cockatoos, African Grey Parrots, Eclectus Parrots and Lovebirds. The first clinically detectable sign of Psittacine Beak and Feather Disease is the appearance of necrotic, abnormally formed feathers. Generally, PBFD is a disease of young birds (up to 3 years of age) however, it has been reported in birds over 20 years old that have been clinically normal most of their life. The virus is spread from hen to the egg, hen to chicks being parent raised, and inhalation or ingestion of infected feather dust or feces. Viral particles in feather dust or dried feces can easily spread on clothing, nest materials, feeding formula or feeding utensils, nets, bird carriers, food dishes and air currents. The virus particles can remain viable in the environment for months, long after the infected bird is gone. Many birds infected with Psittacine Beak and Feather Disease die with in 6-12 months of onset of clinical signs, however, some birds have been known to survive 10-15 years. Death usually occurs from secondary bacterial, fungal, parasitic, chlamydial, or viral infections

Diagnosis:

Psittacine Beak and Feather Disease should be suspected in any bird that shows progressive feather loss and abnormal feather development; however, one can not determine that a bird is infected with the virus just by examination of the feathers. Other disease processes can result in feathers with a similar appearance. Any factor that disrupts the blood supply to the developing feather, including trauma; bacterial or fungal infection of the feather follicles; other viral infections; malnutrition; hormone reactions; and some drug reactions, can cause feather changes similar to those seen with Psittacine Beak and Feather Disease. Identical feather lesions to those caused by PBFD can be produced by pinching developing feathers at or near the level of the pulp cap. On the other hand, birds can carry the virus in their blood but have perfectly normal feathers. Until recently, the primary method of diagnosing PBFD was the demonstration of viral particles in the cells of the feather follicle and/or shaft. This required a surgical biopsy of the affected feather and its associated follicle. Since Psittacine Beak and Feather Disease virus does not affect all feathers at the same time, this test could give a false negative result if the tissue sampled did not contain the virus. A more recent test, PCR analysis, tests for the presence of PBFD virus in the bird’s blood. This is the only effective method available for detecting the PBFD virus in a bird before feather lesions are present. The test only requires a small amount of blood. Some birds may become infected with the virus, test positive, remain infected but never show clinical signs. Other birds, become infected, test positive, fight off the infection and subsequently test negative. Therefore, it is recommended to retest any Psittacine Beak and Feather Disease positive bird 90 days after the initial test. If positive on the second sampling, the bird is considered permanently infected and is expected to manifest clinical disease. A negative sample does not prove that a bird is free of the virus because an incubation period of up to 4 weeks may be necessary before virus can be detected in the blood. Since the virus survives in the environment, the DNA probe can also be used to test samples of feces and/or feather dust taken from the surfaces in the environment.

Sample:

1. Whole blood (0.5 ml) sample in EDTA tube.
2. Tissue (liver, spleen or kidney) in sterile container.
3. Swab of the fresh out surface of liver, spleen or kidney.
4. Paraffin-embedded tissue.

Special Handling:

Store blood and tissue samples at 4°C until pick up or shipment.

Test Code:

A108

1. Dahlhausen B. and Radabaugh C.S. (1993) Update on psittacine beak and feather disease and avian polyomavirus testing. Proc. Assoc. Avian Vet., pp.5-7.
2. Woods et al. (1994) A retrospective study of circovirus infection in pigeons: nine cases (1986-1993). J. Vet. Diagn. Invest. 6: 156-164.