Introduction
Parrot fever has many names, including
Chlamydiosis, Psittacosis and Ornithosis. It is called Psittacosis
when it occurs in people and psittacine (parrot types) birds, and
Ornithosis when it occurs in passerine (pigeons, doves, etc.)
birds. Psittacosis is difficult to diagnose,
and is a mysterious disease that does not "follow the rules" of
typical avian diseases.
Important Regulations
The United States Department of Agriculture regulates the importation
of domestic birds in order to protect the domestic poultry industry. These imported
birds must be accompanied by a health certificate. Upon admission they are quarantined
for 30 days at a special facility and tested for Newcastle disease. During the
30 days they are given food supplemented with medication that will treat Psittacosis.
This medicated feed needs to be continued for at least an additional 15 days
when the bird is released from quarantine.
State Health Regulations
Psittacosis is a reportable disease. When a
positive diagnosis of Psittacosis is made an inspection might occur
to determine the cause of the outbreak, number of birds affected, and
any human exposure. Depending on the specifics of the situation a
quarantine and treatment might be initiated.
Human Health Significance
Humans can get Psittacosis (Chlamydia psittaci)
from birds. Cats get Chlamydia psittaci and show evidence of eye
problems, but there is no evidence that cats can spread this disease
to people. Other species of the Chlamydia bacteria that occur in
sheep, goats, and cattle can cause disease in humans, but those
diseases are not called Psittacosis.
Exposure is usually due to the inhalation of dried bird droppings
that contain the organism, incubation is 6-19 days. Other potential sources
of infection are from respiratory secretions and feathers. Symptoms in people
range from nothing to severe disease with pneumonia. Typical symptoms include
fever, chills, headache, muscle aches and cough. Inflammation of the heart,
liver, and nervous system can occur, with even fatal cases reported. With proper
treatment most people recover. According to the Centers for Disease Control
and Prevention between 50-100 cases of human Psittacosis are reported each year,
with probably many more undiagnosed. Probably due to increased awareness and
diagnostic testing, annual incidence of Psittacosis in humans is decreasing.
Cause
Psittacosis is caused by a bacterium called Chlamydia psittaci
that is an obligate intracellular parasite. It has been isolated from many birds,
especially cockatiels and parakeets. After exposure the incubation period can
vary from 3 days to weeks.
Healthy birds can be carriers of Psittacosis,
shedding the organism in their droppings intermittently. It is also
found in respiratory discharge. Shedding is stimulated in birds by
stress like overcrowding, chilling, and shipping. The shed
Psittacosis bacteria can remain infectious in the environment for
several months.
Symptoms
Birds are masters at hiding any symptoms of illness, especially
in Psittacosis. An apparently healthy bird that is singing and eating in the
morning can be gravely ill or be found dead by the same afternoon. It is imperative
that you tune in to subtle signs of disease in your pet bird, and bring it in
for an exam at the first sign of a problem. If you are unsure, it is better
to be safe than sorry.
Some birds with Psittacosis do not show any
symptoms and can become carriers, shedding the bacterium
intermittently, especially when stressed. Others might get a chronic
illness or become severely ill and die. Symptoms depend on age at
infection, species, virulence of the specific strain of the
bacterium, exposure amount, and stress factors.
Typical symptoms, if present, might include a
fluffed appearance, poor appetite, weight loss, respiratory disease,
and lime green droppings. The droppings might appear to be diarrhea,
but in reality they are usually watery urates, the equivalent of bird
urine. Some birds have ocular discharge, leading to the term "one
eyed cold". These symptoms occur with many other avian diseases, so
it is imperative to follow proper diagnostic
parameters when making this
diagnosis.
This
parrot has a problem as evidenced by its fluffed
appearance. It is fluffed because a disease process is
preventing it from keeping itself warm, so it is trapping
air under its feathers in order to insulate itself. Birds
that do this consistently are ill. Psittacosis can cause
this, but so can many other bird
diseases.
Diagnosis
History
In some cases we have a high degree of
suspicion because a bird has been imported into the country
illegally. This means it has bypassed the USDa quarantine and
treatment facility. These smuggled birds commonly come from
Mexico. They can be purchased at swap meets for a low price, so
you must be wary of these potential disease carriers.
Physical Exam
The physical exam may or may not reveal significant abnormalities.
An exam of a bird gives us limited information compared to dogs and cats.
This is because of the unique anatomy and physiology of a bird. Several examples
will elucidate this point.
- A birds body temperature can go well over 107 degrees
F and still be normal
- They do not have external lymph nodes that
can be felt during an exam
- Their heart rate can easily be up to 500
beats per minute, making it almost impossible to detect murmurs
and arrythmias
- They do not have a diaphragm, the muscle of
breathing that separates the abdomen from the chest
- They use air sacs as a major part of their
respiratory physiology, as opposed to dogs and cats using only
lungs.
- Their keel bone extends far down over their
abdomen, making it impossible to accurately palpate abdominal
organs.
Diagnostic Tests
Since a physical exam on birds yields
significantly less information compared to a dog or cat, we need
to rely more on diagnostic tests.
Taking
a blood sample from the small veins of a bird is a
refined art. One of our nurses
is taking one from the leg vein of a
cockatoo.
A blood panel might be perfectly normal, or
it might show significant problems. This is a blood panel from a bird
positive for Psittacosis on the ELISa test. The arrows point to the significant
abnormalities. The white blood cells (WBC count) are elevated, it is anemic
(HCT is low), and its liver test (aST) is high. These findings give us
an indication that this bird might have Psittacosis, but they can also
occur with other avian diseases though.
Another diagnostic test helpful in Psittacosis
is radiology because it allows us to visualize internal organs. This radiograph is also from the above bird. It has an
enlarged spleen (S), the circular structure in the middle of its coelomic
cavity.
Culture
Culture is used to detect the Chlamydia organism itself,
and is one of the most accurate methods of making an accurate diagnosis.
It is time consuming, requires special techniques and laboratories, and
since shedding of the bacteria can be intermittent, samples need to be collected
for several days. Also, it can take up to several weeks before the result
is available, which defeats the purpose of the test for many ill birds.
Unfortunately, the laboratories that perform this culture are not readily
available to us.
Psittacosis tests
Psittacosis tests have been developed to aid
us in our diagnosis. No test is perfect or applies to every
situation and species. In some cases we will perform several of
these tests to increase accuracy:
- Antibody Tests
These tests check for antibodies made by the immune
system when it is exposed to the Chlamydia organism. Birds that are
stressed, in poor nutritional state, or have other diseases, might not
produce antibodies at all. Also, it is possible for these tests to be
negative early in the course of the disease when the immune system has
not had enough time to produce antibodies.
- Antigen Tests
These tests check for the shedding of the Chlamydia
organism in the feces. Viable Chlamydia are not needed for a positive
diagnosis since they test for antigen or DNA of Chlamydia.
Autopsy
Unfortunately, Psittacosis is sometimes
accurately diagnosed only at necropsy.
This
dark red organ is the enlarged spleen of a bird that
died of Psittacosis.
This
air sac is cloudy, an indication of an infection.
Psittacosis could be a cause of this.
Treatment
Birds that are suspected of having Psittacosis are
immediately isolated. Protective clothing should be worn at all times
when treating these suspects. Routine surgical
masks might not be adequate to prevent exposure.
Birds that are weak, losing weight, or not eating
need supportive care. This consists of fluids
and supplemental feeding. We will frequently hospitalize them until
they regain their strength. The mainstay of treatment is with the
tetracyclines.
There are several different methods to get this
medication into a birds system in order to achieve adequate blood
levels.
- Medicated Feed
Medicated foods can be purchased or made up that contain
1% chlortetracycline (CTC). These need to be fed for 45 days. Acceptance
is variable, so monitoring of food consumption is imperative. Calcium should
not be greater than >7% in this diet because it can interfere with the
tetracycline.
- Oral Doxycycline
This is the drug of choice for oral treatment.
It is also used for 45 days, and is given to birds that are
cooperative.
- Injectable Doxycycline
This drug, also know as Vibravenous, is given
once every 5-7 days. Treatment is given for at least 6 weeks.
Irritation can occur at the injection site, so it must be given
under the direction of a veterinarian.
Prevention
Do not purchase a bird that seems ill or you
suspect has been brought into this country illegally. New birds
should be examined, tested, and quarantined for at least 45 days.
During this 45 days these new birds can be treated also.
People with compromised immune systems should not
be exposed to birds that might have Psittacosis. Gloves, masks, and
protective clothing should be used when cleaning cages and working
around birds suspected of this disease.
Clean cages and feeding bowls frequently, and set
up housing so droppings, food, and feathers do not contaminate other
cages.
Chlamydia psittaci is susceptible to routine
disinfectants. Common ones include Lysol, bleach, 70% isopropyl
alcohol, and Roccal.
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