Test for Psittacosis

Infection

• This disease results from infection by Chlamydophila psittaci bacteria. This organism can be spread through inhalation or ingestion of infectious dust and by biting insects, like lice and mites. Some birds remain infected, but show no symptoms, shedding the bacteria when stressed. Psittacosis bacteria can survive in dried droppings for months, and is also shed in feather dust. Humans are most likely to acquire the disease from exposure to dust or droppings, and rarely pass psittacosis on to other people.

Symptoms

• Psittacosis has an incubation period of three days to several weeks, but birds may not show signs of the disease for years. The symptoms vary by type of bird, with pigeons, ducks and turkeys showing weakness, unwillingness to eat, ruffled feathers, depression, and respiratory or digestive symptoms. Pet birds may also have nervous symptoms and conjunctivitis, though mild cases may show up only as a mild respiratory infection or diarrhea. Humans may suffer from flu-like symptoms, lack of appetite, sore throat and light sensitivity. In some cases, human psittacosis causes severe pneumonia, encephalitis or meningitis.

Diagnosis

• Avian chlamydiosis is diagnosed in live birds by testing a swab or feces. In dead birds, it can be identified from blood, swabs and tissue samples. Veterinarians may identify the organism using immunofluorescence and other staining techniques, though false negatives may occur if the bird is not currently shedding bacteria. ELISA and PCR tests have both been used, and many veterinarians perform more than one test to ensure an accurate diagnosis. Human diagnostic tests are similar, and may be done from swabs or blood samples. Humans may also receive a presumptive diagnosis and treatment if they have psittacosis symptoms and have been exposed to infected birds.

Considerations

• Tests for individual birds should include a whole blood sample as well as a throat or cloacal swab. A test for psittacosis is more likely to produce an accurate result if adequate amounts of material are available for testing. If a sample tests positive, the birds should immediately be quarantined. In large group testing, the environment should also be sampled. Swabs of aviaries, air filters, nesting boxes, counters and other items in the birds' environment can indicate whether the bacteria is present. It's important to clean the environment thoroughly after a case of psitticosis has been detected.

Follow-Up Testing

• Treatment for psittacosis usually involves tetracycline or a tetracycline derivative such as doxycycline. Intramuscular and intravenous injections are both used. Antibiotics are also given orally or mixed with food. Many birds will recover completely, but some may remain infected. After treatment, a psittacosis test should be administered to make sure the bird is no longer a carrier. Human psittacosis treatment generally consists of tetracycline antibiotics and supportive care. No vaccine is currently available.

Warning

• Testing for psittacosis is important in people who have been exposed to infected birds. While Iowa State University reports that fewer than 50 cases are reported each year in the U.S., undiagnosed or unreported cases could result in serious illness. In untreated severe infections, the mortality rate is as high as 30 percent, while cases that receive treatment are rarely fatal.