Most time when birds become infected with polyoma is when they are very young. It is usually fatal at this time. If the bird was exposed and is a carrier,it can shed the disease at any time. It is also more suseptible to illnesses itself. I believe that vaccinating can deter the disease even i the bird is a carrier. I wil investigate and get back to you. Hopefully someone will come along with more info.
Is this happening to your bird? How old is it?
Here you go-From Birds N Ways site:
What is a "Carrier"?
It is occasionally suggested, albeit incorrectly, that the avian polyomavirus vaccine is of limited value in adults because it does not eliminate the "carrier" state. The term "carrier" is frequently and loosely discussed in association with polyomavirus infections in companion birds. By definition, a carrier is "an idividual who harbors a specific organism and is capableof transmitting the infectious organism that can cause a disease but shows no clinical signs". This is a simple definition for a rather complex interaction between infectious organisms and their host. It is a particularly simple definition with respect to avian polyomavirus. In scientific literature which discusses viral infections, the term "carrier" is rarely used. In its place, the term "persistent infection" is used to describe animals that are infected with a virus, shed the virus for an extended period of time and exhibit no easily observed clinical signs. There are then two types of persistent infections: latent infections and chronic infections, and the characteristics of each must be understood when evaluating how to prevent avian polyomavirus infections. The characteristics of these infections are listed in <A href="http://www.birdsnways.com/articles/polyoma.htm#table2">
Table 2.
A common example of a latent infection is the herpes simplex virus that causes "cold sores" in humans. Once an individual is infected with this virus, he remains infected for life and intermittently sheds the virus. More than 10 years ago, it was demonstrated the budgerigars infected with avian polyomavirus develop a latent infection (infected for "life" with intermittent shedding of the virus). Fortunately, an increasing body of information suggests that larger psittacine birds (as well as mice and chickens) infected with polyomavirus are more likely to develop transient, rather than latent infections. These transiently infected non-budgerigar psittacine birds may shed the virus for a certain period, but they appear able to mount an appropriate immune response which controls the infection and eventually stops the bird from shedding the virus. The most important consideration for preventing polyomavirus within a flock is to reduce the opportunity for these temporary shedders to infect other birds.. Toward this end, vaccinating a flock helps to protect uninfected birds from the virus and inhibits the amplification of virus activity through the susceptible birds within a flock. Additionally, the polyomavirus vaccine has not been shown to have any adverse affect on a bird that has already been infected with the virus, making flock vaccination both practical and safe.
The propensity of non-budgerigar psittacine birds to develop transient polyomavirus infections is critical to control of the virus within an aviary. By vaccinating the breeding birds, the cycle of transmission can be reduced, and over time, it should be possible to functionally "eradicate" the virus from a particular aviary. Even if non-budgerigar psittacine birds were to develop latent infections, vaccination may still be a valuable method of preventing disease. Vaccination programs in other species (humans, cats, dogs, cattle, etc.) have been very effective in controlling many viruses that are known to cause latent infections.
Because budgerigars respond differently to polyomavirus infections than do non-budgerigar psittacine birds, the recommendations for controlling infections in non-budgerigar psittacines may not apply to budgerigars. Research is currently under way to determine how to effectively vaccinate budgerigars for polyomavirus. It is important that unvaccinated psittacine birds not come in direct or indirect contact with budgerigars.
