Avian Polyomavirus - Avian Diseases

Information kindly supplied by www.avianbiotech.co.uk


Description
Polyomavirus - This virus, also referred to as Budgerigar Fledgling Disease is a member of the papovavirus family. Polyoma virus is a 40-50 nm diameter in size, containing a double-
stranded DNA genome of approximately 5000 basepairs.

This pathogen is considered one of the most significant threats to cage birds around the world. This highly infectious disease effects most if not all parrot species. Polyoma seems to be most problematic among neonates (young birds) between the ages 14-56 days. Young birds often die, while adult birds can develop a certain level of immunity. Polyoma is believed to have an incubation period of approximately two weeks or less.


Transmission
The disease can spread from one bird to another via feather dust, feces, aerosols and parental feeding of chicks; direct contact or contact with infected environments (incubators, nest boxes).. Birds that are infected but do not have obvious signs of infection are often responsible for spreading the virus to an aviary or bird store. Carrier state maybe possible in adult birds.


Symptoms
Swollen abdomen, depression, loss of appetite, anorexia, weight loss, delayed crop emptying, regurgitation, diarrhea, dehydration, feather abnormalities hemorrhages under the skin, dyspnea, polyuria, ataxia, tremors, paralysis, acute death.

Some birds die without any clinical symptoms. Adult birds may die of secondary infection from bacterial, viral, fungal or parasitic pathogen.


Prevention
Isolate all birds shedding the disease. Disinfect all contaminated surfaces with an oxidizer such as chlorine bleach (Polyoma virus is resistant to many disinfectants). *Alcohol does not work as it is not an oxidizer. A vaccine is available, however this option may cost as much as $40-60 per bird: additionally booster shots are required each year and the effectiveness of the vaccine in younger birds is in question. Quarantine all new birds and use nested primer PCR testing to determine whether or not birds are infected.


Treatment
No Known treatment at this time


Diagnosis
Nested primer PCR testing, and sequence analysis of PDV DNA; histopathology.


Sample
When testing individual birds, a whole blood sample is recommend in conjunction with a cloacal swab when possible. If the sample tests positive, then the bird should be placed in quarantine and re-tested in 4-6 weeks. If the bird tests negative the second time, then a third test is recommended. Post mortem samples of liver, spleen, or kidney tissue in a sterile container, postmortem swabs may also be submitted. Environmental testing using swabs of aviaries, countertops, fans, air-filters, nest-boxes etc. is extremely effective in determining the presence of Polyoma DNA in the environment. *It is recommenced to submit both a whole blood and cloacal swab sample for analysis when possible.


Handling
Prior to shipping samples should be stored at 4 C. (refrigerator). Samples must be shipped in a padded envelope or box. Samples may be sent by regular mail, but overnight is recommended.


Limitations
Vaccination of birds using a killed virus or DNA vaccine prior to testing does not affect the accuracy of a PCR test.


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Avian Polyomavirus