Circovirus (Psittacine Beak and Feather Disease)Infection is primarily seen in young birds. Typical signs could be feather loss (areas which the bird cannot pluck included), lack of powder down, pigment loss in feathers, abnormal pin feathers.
This can of disease has no treatment whatsoever. It is suggested that the bird must be totally isolated or sometimes euthanized.
(sources derived from Merck's Manual for Pet Health 2007)