Polyomavirus in Parrots

October 24, 2012


This viral condition is very frequent in birds, especially in the young. Although all avian species are susceptible to this virus, the following are particularly sensitive: parakeets, large parrots, macaws, eclectus, lovebirds, budgerigars and cockatiels. This disease was formerly known as Budgerigar Fledgeling Disease.

Three different polyomaviruses are found in birds:

  1. A virus causing lesions similar to papilloma has been isolated in some European finches (rare).
  2. A virus causing lesions similar to papilloma has been isolated in an African grey parrot (Timneh).
  3. Budgerigar Fledgeling Disease: A virus resulting in a high mortality rate in psittacine birds, especially in Canada and the United States. It is the main form of the virus and the one we shall discuss here.


The virus moves from parents to young at mealtime (regurgitation). The aviculturist can then transmit the disease when hand-feeding if the syringes used are not sterilized between each meal.

The virus spreads in the epidermal cells, especially in the feather follicles, and can be found in feather dust. The respiratory tract is suspected to be another place the virus may enter via inhalation of feather dust.


The parents are carriers, which mean that they can transmit the disease but do not develop it. The disease appears in young birds with immature immune systems experiencing a stressful situation: weaning, travel, etc.


  • Distended abdomen
  • Absence or malformation of down
  • Delayed growth of tail feathers and contours
  • Dehydration
  • Cloacal region soiled by urine rather than droppings
  • Skin can become reddened
  • Death
  • Crop is often full (which demonstrates that the condition has progressed very quickly).

The mortality rate can vary from 25 to 100 per cent in high-risk young exposed to the disease.

How can you determine if your bird is affected or is a carrier?

Very sensitive tests are now available and can be performed by your veterinarian. These tests are usually performed routinely in babies showing signs of illness. Testing is strongly recommended for parents that have had chicks die at a young age.


There is unfortunately no treatment for this devastating disease.


It is important to stop reproduction for a certain period of time and eliminate affected subjects, or at least prevent them from breeding.

Follow very strict hygiene measures. Disinfect all utensils and wash hands between each bird. Clean and disinfect the environment.

Separate breeders that have never produced abnormal young from those that have had problems.

Avoid all contacts with other breeding operations. Close the breeding facility.


Recent studies have shown that the above-mentioned preventive measures, associated with a vigorous vaccination program help to control this disease in breeding operations.

It should be remembered that the virus is very stable and can remain in the environment for many months. It has been detected in the air ducts of pet stores!