Common at the time of weaning and fledglings usually die 12 to 48 hours after developing symptoms.
Chronic form has intermittent symptoms.
Carrier state is possible. Immunodiffiusion and virus neutralization can be used to detect polyomavirus antibodies in exposed birds. This antibody response is transient and birds revert to seronegative over a short period of time. Best test for birds shedding polyomavirus is a cloacal swab. Transmission can take place through feather dust and excrement and through parental feeding of chicks.