Polyomavirus Infection in Birds

By Gregory Rich, DVM; Rick Axelson, DVM

What is polyomavirus infection?

Avian polyomavirus infection (APV) of pet birds belongs to the family Polyomaviridae. APV can cause benign feather lesions in budgies, slow crop emptying in weanling parrots, hemorrhages on the skin, or acute death. Species particularly susceptible to APV infection include budgies, Eclectus parrots, Caiques, and Hawkhead parrots.

How do birds become infected?

Direct exposure of non-vaccinated birds to a bird infected with polyomavirus or a non-symptomatic carrier is the most common route for transmission. Humans that have handled a sick bird or carrier bird, used feeding utensils from sick baby birds, or do not thoroughly disinfect food and water bowls can carry the virus on their person and infect other birds. Feather dander and bodily fluids from infected birds are also a frequent source for transmission to other birds.

What are the clinical signs of polyomavirus infection?

Infected birds generally present with clinical signs 7-14 days after exposure to the virus. Some infected birds may show depression, anorexia, weight loss, delayed crop emptying, regurgitation, diarrhea, wet droppings, dehydration, difficulty breathing, abdominal enlargement, hemorrhagic areas under the skin, and tremors for 12-48 hours before death. Mortality can be high, reaching 100% in birds less than 15 days old. Most juvenile and weanling parrots infected with polyomavirus die quickly with no clinical signs.

"Most juvenile and weanling parrots infected with polyomavirus die quickly with no clinical signs."

Budgerigars that recover from the infection are often left with abnormal feathers (Budgerigar French Molt). Birds that recover likely remain carriers and can shed the virus despite showing no signs of illness.

How can I tell if my bird is infected?

Birds, especially baby birds, die quickly; if you have a baby bird that dies suddenly, it should be examined by a veterinarian within 24 hours of death. Either a necropsy (veterinary autopsy) or laboratory testing will be necessary to accurately determine the cause of death. Both sick and healthy birds can be tested using a specific DNA probe of whole blood or either an oral or cloacal swab. Your avian veterinarian will send these samples to a reference lab for testing.

My bird is healthy. Should it be tested?

This can best be decided by your veterinarian. However, if you plan to purchase another bird, both should be screened for APV, as either or both birds can be carriers without showing signs.

How is polyomavirus infection treated?

"There is no definitive treatment for APV."

There is no definitive treatment for APV. Birds with mild hemorrhaging might benefit from vitamin K injections and supportive veterinary care. Often, the disease progresses so quickly that no treatment will be effective.

How can I prevent polyomavirus infection?

Manual removal of droppings and feathers followed by careful disinfecting of the environment can help reduce viral contamination of the environment. The DNA probe test should be done on currently owned birds and newly acquired birds before they are put together. Because birds can shed the virus intermittently, several negative tests are needed to be somewhat certain that a bird is not a carrier. A polyomavirus vaccine is available for selected psittacine birds (parrots) to aid in the prevention of APV.

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