Parrot Fever (Chlamydia)
What is it and what do I Need To Know?
Steven D. Garner, DVM, DABVP Diplomate,
American Board of Veterinary Practitioners,
Chief of Staff, Safari Veterinary Care Centers,
Parrot Fever is a disease of pet birds caused by the organism Chlamydia psittaci. The disease is also known as psittacosis, chlamydiosis, ornithocosis and Chlamydia. Chlamydia can cause illness in parrots, mammals and people. Chlamydia is different from many bacteria in that it is smaller and is an obligate intracellular organism i.e. it depends on the birds cell that it has invaded to generate energy because it can not do it on its own. Birds that are infected with Chlamydia may shed the organism intermittently in their stool without showing any signs of illness (these are called carrier birds) or birds may become severely ill and die with out treatment. Shedding rate of organisms is highest in young birds or those that were recently exposed. Chlamydia can usually be detected in the feces 10 days prior to the onset of clinical signs. In carrier birds, organisms may be shed following a stressful event i.e. other illness, bird show, weaning, post purchase, etc. Because Chlamydia lives hidden inside the cells of the bird, it can be shed intermittently, and in many cases, lack of any clinical signs of illness that makes diagnosis of the infected bird difficult.
Chlamydia organisms enter the bird by being breathed in or swallowed in contaminated food or water. Clinical signs in a bird infected with Chlamydia may include any combination of the following: ruffled feathers, difficulty breathing, discharge from the eyes and/or nostrils, weight loss, poor feather condition, depression, loss of appetite, vomiting and/or diarrhea. Chlamydia infections often cause damage to the liver. Birds with severe liver damage may pass lime-green urates (urates are the solid portion of the urine and are normally white). There are many causes of liver disease in birds, Chlamydia is just one of them.
Birds are able to hide signs of illness from their owners often until they are critically ill. If your bird is showing any of these signs, it should be taken to your avian veterinarian as soon as possible. A complete physical examination should be done to evaluate your bird for any physical signs of disease. In addition, there are several laboratory tests that can be done to better evaluate the bird for evidence of disease.
Some of these diagnostic tests are discussed below:
- Fecal Examination: Examination of the stool under a microscope to look for parasites, bacteria, yeast, fungus and abnormal cells that may reflect disease.
- Complete Blood Cell Count: Evaluation of red blood cells (carry oxygen to cells) and white blood cells (fight infection) in a blood sample. Low red blood cell counts are typical of anemia. High white cell counts are typical of infection.
- Serum Biochemistry Profile: Evaluation of blood levels of protein, electrolytes, liver enzymes, kidney values, and glucose. Changes in these values can reflect the health and function of the internal organs.
- Bile Acid Levels: Bile is produced in the liver. Birds with poor liver function will often have abnormally high levels of bile acid in the blood.
- Radiographs: Allow for the ability to see the outline of the internal organs and bones. Organs may be smaller or larger than normal, and foreign objects, tumors, eggs, broken bones or frail bones due to calcium deficiency can be seen.
Changes in laboratory tests that should make one consider Chlamydia as one of the possible causes of disease in a sick bird include: anemia (low red blood cell count), elevated white blood cell count, elevated liver enzymes, and/or elevated bile acid levels. With radiodiographs, one may see enlargement of the liver and spleen and evidence of air sac and/or lung disease. Any combination of these signs may be present depending on the age and species of affected bird and severity of the infection.
There are several different tests available designed specifically to evaluate for Chlamydia. Each test has its own strengths and weaknesses. Some tests can be done in the veterinarian’s office but most require shipment to a laboratory that is specialized to perform these tests. Some of these tests are designed to detect the presence of the Chlamydia organism in swabs of tissues, mouth or feces while other tests are designed to detect antibodies in the blood (antibodies are specialized proteins produced by the body to protect it from the Chlamydia organism). Your veterinarian will select the most appropriate test based on the age and species of bird, clinical condition of the bird (sick vs. healthy), and whether it is a pre/post purchase evaluation. I recommend Chlamydia testing on all birds as part of a pre/post purchase examination and prior to shipping or introduction in to a pet bird collection.
C. psittaci is contagious to people causing infection with flu like symptoms i.e. spiking fever, night sweats and pneumonia. Anyone in contact with an infected bird is at risk however, those individuals on immunosuppressive therapy for cancer or organ transplant and those people with other severe illness such as hepatitis, cancer, emphysema or AIDS are particularly at risk.