Psittacine Beak & Feather Disease - Part 2
A virus known for quite some time
Initially studied in 1975 on Australian parrots, this disease is due to a circovirus, which mainly affects parrots in Australia. It has developed over several years.
Deformation of feathers and beak
The virus prevents normal production of keratin in the body, which is the protein necessary for the formation of feathers, the beak and leg scutes.
Initial symptoms are a deformation of several feathers after moulting and incorrectly developed new feathers. The feathers are hooded in their sleeve and sometimes have small blood spots at the base. Gradually, the bird plucks to the point of becoming completely naked. The beak of cockatoos becomes shiny because keratin powder which is normally present on the surface is not properly synthesized (see photo 1: PBFD-infected cockatoo). The leg scutes deform and the beak loses its rigidity, softening and sometimes completely falling off in extreme cases.
In the wild, the bird will die quickly as it will be incapable of flying or feeding
itself. In captivity, it can live much longer (several years) with the virus, with care from its owner.
Immunodeficiency
This disease also causes an immunodeficiency (affecting its defence systems), which further weakens the bird by allowing all sorts of other opportunistic infections to emerge.
A perplexing disease that develops differently in different species of parrots
Among infected birds, many remain healthy carriers of the virus without actually developing the disease. They are nevertheless contagious.
The parrots most susceptible to contracting the disease are Australian parrots, for example all varieties of cockatoos and eclectus. The disease is particularly serious in cockatoos as it will in general lead to the death of the animal.
South American parrots (macaws, amazons, pionus, etc.) are much more resistant and
in general will spontaneously eliminate the virus after several months.
The susceptibility of African parrots (the African Grey, for example) seems intermediary: very few infected adults develop the disease, most remain healthy carriers. However, this virus is devastating for young greys between weaning and six months because they can die suddenly in two to three days if treatment is not possible.
Parakeets (budgerigars, cockatiels, lovebirds, etc.) are also susceptible, but are most often attenuated forms (see photo 2: budgerigar infected with PBFD). They can however act as reservoir of the virus and transmit it to parrots.
A simple diagnosis
PCR tests exist to detect the virus’ DNA in the bird’s blood or in the end of its feather. These tests have been used for a long time and their results are reliable.
A positive test does not mean the same thing for each species of parrot:
- A positive cockatoo is unfortunately very likely to develop the disease.
- A positive adult African parrot (Grey, Senegal, etc.) that does not exhibit any symptoms will in general remain positive but rarely develops the disease; however, it remains contagious to the other members of its flock and its chicks. It is nevertheless possible that it will eliminate the virus over time.
- A positive South American parrot (macaw, amazon, etc.) will very rarely develop the disease. It is probably that it will spontaneously eliminate the virus after several months. It is therefore useful to redo a PCR test after 4 to 6 months after a positive test to verify that the bird is still a carrier.
It is therefore strongly recommended to conduct a test before purchasing a bird and then undertake a follow-up examination after purchase because the incubation period can be several weeks.
Unfortunately, no specific or effective treatment exists. A vaccine is under development.
Dr J-F Quinton, Feb 2011. (Photo Credits: Advétia)