This disease was first described in Australian cockatoos in the early 1970's. Since that time, the disease has infected over 50 different species of birds. The virus causing the disease works slowly. The disease is often called "Bird AIDS" due to some similarities between it and the human disease of AIDS.
What causes beak and feather disease?
For many years, the cause was unknown. We now know that a virus (Psittacine Beak and Feather Disease virus, which is a Circovirus) causes the disease.
How do birds become infected with the virus?
Susceptible birds can become infected through the oral cavity, nasal passages, and through the cloaca (the common receptacle in which the urinary, gastrointestinal and genital tracts empty). The virus is readily shed in the feces and in the crop. Viral particles shed into the crop (storage part of the stomach) may explain how the virus is passed from parents to offspring (during feeding of crop milk). High concentrations of the virus are shed in feather dust from infected birds, which increases the chances of its spread by people, clothing, hair etc.
What are the signs of beak and feather disease?
"Once signs are seen, most birds die from secondary infections within 6-12 months."
Infected birds may take weeks, months or years before showing any clinical signs, often depending on how old the bird is. The first visible clinical sign is necrotic (dead) or abnormally formed feathers. Once signs are seen, most birds die from secondary infections within 6-12 months.
Clinical signs involve lesions affecting the beak, feathers, or both. Most commonly, young birds (less than 3 years old) are infected with the virus. Several forms of the disease may be seen; the form of the disease seen in an individual bird is influenced by the age of the bird when infected.
Peracute Form: This occurs in neonatal (recently hatched) birds; signs seen are septicemia ("blood poisoning", caused by bacteria and bacterial toxins in the blood stream) accompanied by pneumonia, enteritis (infection of the small intestine), weight loss, and death. The diagnosis is easily missed if a necropsy (post mortem / autopsy) and histology (microscopic examination of tissues) are not performed on birds that die suddenly, since these young birds die before feather abnormalities are recognized.
Acute Form: The acute form develops in young birds infected as they develop their first feathers. The signs include depression for a couple of days followed by sudden changes in the formation and appearance of the developing feathers, including premature molting. Some of these birds may die in 1-2 weeks
Chronic Form: This form occurs in older birds, and these birds progressively develop abnormal feathers in a symmetrical pattern over successive molts. Short, clubbed feathers and deformed curled feathers are seen. These changes occur in birds that have survived the acute stage of the disease. If affected birds live long enough, they may develop baldness.
Beak deformities may develop, and if they do, these occur after a long course of the disease where substantial feather changes have taken place.
How is the disease diagnosed?
"A blood test using a DNA probe is the best way to diagnose the disease."
A skin and feather biopsy can be used to eliminate other causes of abnormal skin and feathers. It is not 100% diagnostic for beak and feather disease but can be strongly suggestive of it. A blood test using a DNA probe is the best way to diagnose the disease; it is often performed at the time of the biopsy.
How do I know if my bird is infected?
Birds can be screened for the virus using a simple blood test. New birds should be screened for the disease; if the bird is infected, it probably will not show clinical signs for quite a while, and the owner needs to be aware of this. Many new birds are sold with a health warranty. If a bird tests positive, it should be covered under the warranty and the owner may decide to return it. Any owner purchasing a new bird should have both the resident bird and new bird tested before bringing the new bird into the household.
How is beak and feather disease treated?
Unfortunately, there is no treatment for the disease and it is usually fatal. Supportive care can be given and a stress-free environment can extend the life of the bird for quite some time. Infected birds should be kept isolated from non-infected birds as the disease is easily transmitted.