PBFD is caused by a circovirus which kills the cells of feathers and the beak. It is a naturally occurring infection in Australian cockatoos but it is found in all types of parrots as well as lovebirds, cockatiels, budgies and parakeets. African greys are particularly badly affected. PBFD is a dreadful disease which normally results in the death of affected birds and the decimation of young birds in infected collections. Chronically affected birds become immunosuppressed and may succumb to other diseases due to their depressed immune system. A positive result from a bird with no feather problems or other clinical signs may mean either that the bird is a carrier or that it has been recently exposed to the virus. In these cases we recommend isolating the bird and re-testing in about 90 days. We also recommend that the second sample is collected directly from a vein by venipuncture to avoid contamination. The majority of birds which are merely exposed will develop an immune response and eliminate the infection. Those still positive at the second test should be considered as carriers. One day they are likely to show the disease, and become potential source of infection to other birds.