Psittacine Beak and Feather Disease Virus (PBFD)

Test code: S0088 - Qualitative detection of PBFD virus by polymerase chain reaction

S0088 is included in the Psittacine PCR Screening Panel

Psitticine Beak and Feather Disease (PBFD) is a chronic disease characterized by feather dystrophy and loss, beak deformity and ultimately, death. It is caused by a non-enveloped icosahedral DNA virus belonging to the family Circoviridae. The disease has been reported in Australia, North America, Europe and Asia. Most species of parrots, such as cockatoos, African grey parrots, eclectus parrots and lovebirds, can be infected by this virus. Recent study also shows that PBFDV can cause feathering problems in some of the ringneck parakeets and budgerigars in South Africa.

PBFD virus usually infects birds less than 3 years of age. The virus is spread from mother to egg or directly to chicks. Viral particles can be spread in feather dust carried by air currents, dried feces or even on the clothing of human handlers. Nest materials, feeding formula, feeding utensils, nets, bird carriers, food dishes and other fomites are easily contaminated with this virus. Since the virus particles can remain viable in the environment for months, long after the infected bird is gone, there is a high potential for widespread infection of an entire flock of birds.

The first clinically detectable sign of PBFD is the appearance of necrotic, abnormally formed feathers. Many birds infected with PBFD die with in 6-12 months of onset of clinical signs. However, some birds have been known to survive 10-15 years and become chronic carriers. Death usually occurs from secondary bacterial, fungal, parasitic, chlamydial, or viral infections.

PBFD should be suspected in any bird that shows progressive feather loss and abnormal feather development. Molecular testing of the PBFD virus is needed to rule out other disease processes that can also result in abnormal feather development such as trauma, bacterial or fungal infection of the feather follicles, other viral infections, malnutrition, hormone problems, and adverse drug reactions.

Routine screening for PBFD virus should also be performed for any new purchase or addition of birds to a flock since quite a number of carriers have perfectly normal-looking feathers. It is still unclear why some birds become carriers of the disease while others do not. However, even if only one carrier is introduced to a flock, the virus can rapidly spread and wipe out the entire flock.

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 requires a surgical biopsy of the affected feather and its associated follicle. Since PBFD virus does not affect all feathers at the same time, this test could give rise to a high false negative result due to sampling variation. Molecular testing (Ypelaar et al., 1999) for the virus in blood, a highly homogeneous source of sample, significantly reduces the frequency of false negative results. The high sensitivity and specificity of PCR detection also enhance the successful screening of carriers, who may have very low levels of the virus. Molecular testing requires only a small amount of blood, rendering it less traumatic, especially for small birds.

Any bird testing positive for PBFD virus should be re-tested 90 days after initial test and treatment. This is to ensure that the bird is not transforming into a chronic carrier. In addition, since the virus survives in the environment, molecular testing can also be used to test samples of feces and/or feather dust taken from the surfaces in the environment so as to stop the spread of the disease.

Utilities:

• Confirm the disease causing agent
• Environmental monitoring
• Ensure that bird populations are free of PBFD
• Early prevention of spread of the virus among bird populations
• Minimize human exposure to the virus
• Safety monitoring of biological products and vaccines that derive from birds

References:
Ypelaar, I., Bassami, M.R., Wilcox, G.E. and Raidal, S.R. (1999) A universal polymerase chain reaction for the detection of psittacine beak and feather disease virus. Vet. Microbiol. 68:141-148.

Specimen requirements: 0.5 ml whole blood in EDTA (purple top) or ACD (yellow top) tube, or cloacal swab, or swab of the outer surface of liver, spleen or kidney, or 0.5 ml fresh or paraffin-embedded tissue, shipped overnight at room temperature; or frozen tissue shipped frozen.

For specimen types other than those listed here, please call to confirm specimen acceptability and shipping instructions.

For all specimen types, if there will be a delay in shipping, or during very warm weather, refrigerate specimens until shipped and ship with a cold pack unless more stringent shipping requirements are specified. Frozen specimens should be shipped so as to remain frozen in transit. See shipping instructions for more information.

Turnaround time: 2 business days

Methodology: Qualitative PCR

Normal range: Nondetected