Infectious Disease of Parrots
Katy A. Parr, DVM
Beak and Feather Disease
Beak and Feather Disease is caused by a virus which attacks
the beaks and feathers of parrots.
There is no cure for this disease, and it is spread through
the feather dust and bodily fluids via inhalation, ingestion, or
contact with open wounds. Infected
birds may have abnormally formed feathers and beaks which get
worse with each molt, or may have no symptoms at all.
Affected birds often have additional bacterial or fungal
infections as a result of the beak and feather abnormalities.
Birds infected as babies usually die, while birds infected as
adults may die, or become carriers and develop disease later in
life. Beak and feather
disease is diagnosed through samples of blood or damaged feathers.
Birds are eventually
euthanised due to the severity of the deformations produced by the
Papillomas are wart-like growths which are usually found in
the mouth and vent, but can also affect the face and internal
organs. They can still be seen from time to time but are less
common now that many birds are captive bred instead of wild
caught. Both Herpes
virus and Papillomavirus have been implicated as the cause for
this disease, which is lifelong, and can have varying effects on
the bird. In some birds the growths become large enough to block
the normal function of the mouth or vent, and require surgical
trimming. In some
cases, papillomas can lead to cancers of the liver and pancreas,
and eventually death.
PDD (Proventricular Dilatation Disorder)
The Bornavirus which causes PDD was only very recently
disease is latent, meaning that the virus may be present for many
years before signs of disease develop.
The virus attacks nerves, especially those of the digestive
system, so signs vary from vomiting and passing whole seed in the
stools, to wobbling or seizures.
There is currently no cure for PDD, so it is eventually
fatal, but some medications may help improve quality and length of
Polyomavirus is very contagious and is most commonly a
problem in breeding colonies, especially in budgies.
Signs of this disease may include abnormal feathers,
bruising, distended abdomen, or sudden death.
It is spread via feather dust and bodily fluids which are
aerosolized, thus it is very difficult to decontaminate the
environment. There is
no treatment, but a vaccine is available for prevention. This
vaccine is usually recommended in baby birds, breeders, or those
exposed frequently to other birds from outside the home (e.g. at
This disease is caused by the bacterium Chlamydophila
psittaci which is contagious to people.
It can cause respiratory disease and liver disease, so sick
birds may have a variety of signs of illness ranging from
sneezing, runny nose, eye discharge, and conjunctivitis, to
diarrhea, yellow urates, vomiting, and lethargy.
However, birds can be carriers of the disease and never
show clinical signs. Psittacosis is spread through contact with
body fluids from infected animals or people, but it is usually not
fatal and is curable with antibiotics.
Gram Negative Bacteria
There are many steps to identify bacteria.
One step in identification is a procedure called Gram
staining, which separates bacteria into two large groups called
“gram-positive” bacteria and “gram negative” bacteria.
These are very broad groups, and do not tell us the exact
species of the bacteria, but help the veterinarian to determine
the general health of the bird’s respiratory or intestinal
tract. Birds should
normally have mostly (90%-100%) gram positive bacteria, while
cats, dogs, reptiles and people can normally have many gram
negative bacteria. If
gram negative bacteria are detected in the nasal sinus, crop smear
or fecal smear of your bird, your veterinarian may culture the
area in question and prescribe antibiotics and/or pro-biotics as
Yeast infections in birds most commonly affect the
digestive system, and may overgrow due to a variety of conditions.
Baby birds often get yeast infections of the crop or stool
because they are fed warm, soft foods which are a perfect
environment for yeast growth.
Adult birds that dunk their food in water, or have a diet
high in sugar may also get yeast infections.
Birds who have yeast infections may or may not show signs
of infections such as vomiting, scratching the beak, or diarrhea.
These infections are usually easily treated with
Normal healthy birds are not usually prone to aspergillosis;
however individuals with weakened immune systems, such as those
with nutritional deficiencies, are more susceptible.
Aspergillosis is caused by the fungus Aspergillus
sp. which is naturally found in the environment.
You may have seen Aspergillus
sp. growing on rotten fruits and vegetables, stale bread, or
as a component of mildew in your home.
It is so common in the environment that it is impossible to
completely eradicate. You
can however reduce your bird’s exposure to it by promptly
removing any uneaten soft, moist foods from your bird’s cage,
and routine cleaning of the cage.
Aspergillosis most commonly causes respiratory disease, and
is often not noticed until the pet is very sick.
Common signs include sneezing, nasal discharge, general
weakness, inability to tolerate exercise or
handling, open mouth breathing, and increased breathing effort.
Severely affected birds often need to be hospitalized.
Blood tests can be done to confirm whether a bird has
aspergillosis, but diagnosis is often difficult and may require
is usually with liquid medications and nebulizations (aerosol
medication) for several months.
Some birds recover from aspergillosis, but many do not.
Giardia and other protozoa
Protozoa are microscopic parasites, which can cause
diarrhea, malodorous stools, feather-picking, or even no signs at
all. It is usually
spread by oral contact with infected feces. In birds, flagyllated
protozoans can be very difficult to clear completely, and may go
away for some time, then return in times of stress.
Although this can be a frustrating infection, it is still
important to treat it to keep your bird as healthy as possible.
The most commonly diagnosed mites in birds are the “Scaly
Leg Mites” or Knemidocoptes
sp., which is most often found in budgies and canaries.
These mites burrow into and around the beak, and under the
skin on legs, causing a spongy, scaly appearance.
Canaries may also have tracheal mites, or Sternostoma
tracheacolum, which can cause respiratory disease. Treatment
for both types of mites consists of a series of injections which
kill the mites.
While not all diseases and treatments are included
here, these are some of the most common ones.
Contact your Chicago Exotics veterinarian if you have more
questions or notice any unusual signs in your pet bird.
Having your bird examined yearly by an avian veterinarian
increases the likelihood of detecting any of these diseases early,
before they become a severe condition for your bird