Fledglings, young adults and mature birds have been described with polyoma virus. Some birds that survive may develop feather or beak malformations. Sensitive and virus specific DNA swab tests are now commercially available for screening live birds by cloacal swab. This testing modality confirms the presence of polyoma virus in the tested sample. You avian vet should have this testing available.
Positive results mean only that there is viral DNA present in the submitted sample.
This does not say clinical disease is present, but strongly suggests a carrier state. A twice annual screening of breeding collections. Ideally swabbing just at the end of laying eggs is best, the birds are stressed by laying and this increases the chances of them shedding virus. Closed aviary protocols are important to follow. All birds in one location need to be screened and found negative and no new birds are added to this location for any reason until they have had appropriate testing.