What is chlamydiosis?
Chlamydiosis, also called psittacosis or parrot fever, is a common disease of parrots caused by a bacterial infection. It is also referred to as ornithosis in birds other than parrots, like canaries, doves, and pigeons. While this disease can occur in any bird, it is more common in cockatiels, budgerigars (budgies), amazon parrots, macaws, and lorikeets.
The disease can cause chronic infections, infections without visible symptoms (asymptomatic), or sudden death. The disease can also be transmitted to people, particularly if they are immunosuppressed. It is not associated with the venereal form of chlamydia that affects people.
What causes chlamydiosis?
Chlamydiosis is caused by infection with a bacterial organism called Chlamydia psittaci (C. psittaci). This organism shares similarities with viruses and parasites in that it must live inside host cells to survive and reproduce. C. psittaci is classified as bacteria but, like many viral organisms, it lives inside the cells of the bird’s internal organs, making it difficult to kill with standard antibiotic treatment. (Photo courtesy of Dr. Gregory Rich, DVM.)
What are the signs of chlamydiosis in birds?
Chlamydiosis can cause many different clinical signs, so it should be suspected in any sick bird with generalized signs of illness. Some birds are infected with this disease without exhibiting any signs of illness and are considered asymptomatic carriers. General signs include:
- Decreased appetite
- Weight loss
- Lethargy
- Diarrhea
- Nasal or ocular discharge
- A fluffed-up appearance
- Breathing difficulties
C. psittaci may affect some or all organ systems, most commonly the liver, spleen, respiratory tract, and digestive tract. Commonly, chlamydiosis causes chronic respiratory symptoms, such as sneezing, coughing, runny eyes or nose or gastrointestinal signs (diarrhea).
In amazon parrots and macaws, chlamydiosis causes lime-green or yellow-green feces and urates (the normally solid, white part of the droppings) because the Chlamydia organism infects the liver, causing a severe form of hepatitis. However, these changes to the droppings are not always seen, and other diseases that affect the liver can also cause discolored droppings.
Birds that are asymptomatic carriers of C. psittaci may harbor the organism in their liver or intestines without showing any signs of illness and spread it to other birds (and humans) through their droppings and respiratory tract secretions. Chlamydiosis is usually spread from bird to bird when they are housed in close quarters, such as in a pet store or breeding facility. The organism can be found in nasal secretions, fecal material, and feather dander of infected birds. For this reason, all newly acquired birds should be tested for chlamydiosis.
How is chlamydiosis diagnosed?
Several tests (serology, PCR, culture) are available for diagnosing chlamydiosis in birds, but none are 100% reliable. Your veterinarian will use a combination of tests to reach a diagnosis, including:
- Complete blood count (CBC): An elevation in white blood cells suggests infection.
- Chemistry profile analysis: Liver enzymes are commonly elevated with chlamydiosis.
- Polymerase chain reaction (PCR): Tests for Chlamydia genetic material in the bird’s blood, fecal material, or swabs of the oral cavity. The presence of Chlamydia genetic material only indicates that the bird was exposed to the organism; clinical signs and further testing are required to determine whether it is the cause of the illness.
- Protein electrophoresis (EPH): This test does not specifically test for chlamydiosis, but it allows your veterinarian to look for patterns of change in a bird’s antibody levels, which suggest that the bird is fighting infection.
- Other blood tests: Some tests can find specific antibodies to this organism, but they cannot distinguish an active infection from a previous exposure to the bacteria.
- Fecal tests: Your veterinarian may check your bird’s feces for the presence of Chlamydia, but infected birds may not actively shed the bacteria in their stool, so these tests are unreliable on their own.
- Postmortem tests: Special tests can check for the presence of C. psittaci in the liver, spleen, heart, and air sacs of birds that have died. Tests run on deceased birds are useful for veterinarians who must decide whether to treat birds that were in contact with the dead bird, even if the other birds are not showing signs of illness.
How is chlamydiosis treated?
Chlamydiosis is usually treated with oral or injectable doxycycline, which is a type of antibiotic. Drug treatment should go on continuously for the recommended period of 45 days, without interruption, because doxycycline only kills the Chlamydia organisms when they are active and dividing. The life cycle of these organisms is prolonged, with possible periods of dormancy (ceasing to be active for a period of time), which is the reason for a long treatment period.
You may choose to give oral medication at home, twice a day, for 45 days, or you may visit your veterinarian for weekly shots of long-acting doxycycline for six weeks. Doxycycline, like other antibiotics, kills helpful and harmful bacteria in a bird’s gastrointestinal (GI) tract, so long-term antibiotic treatment may predispose the bird to yeast infections.
Many veterinarians prescribe probiotic medication during treatment to help promote the growth of helpful GI bacteria. After the 45-day treatment, some veterinarians recommend repeating tests for C. psittaci to ensure the treatment was effective.
Can chlamydiosis affect humans?
Yes, C. psittaci can infect humans. Chlamydiosis is a zoonotic disease, which means it can be passed from bird to human as well as bird to bird. Infection in humans usually occurs through inhalation or ingestion of contaminated fecal matter or dust that contains dried respiratory tract secretions from an infected bird. To be clear, this is not the venereal form of Chlamydia.
In humans, chlamydiosis often causes flu-like respiratory signs such as fever, sweating, headache, fatigue, muscle pain, inappetence, nausea, vomiting, diarrhea, and a dry cough. If left unattended, chlamydiosis in humans may progress to pneumonia.
If you develop these signs, particularly if you have been around a bird, seek help from your medical doctor. Since chlamydiosis is a zoonotic disease, all new pet birds should be examined by a bird-savvy veterinarian and have some form of testing for this disease.
