In humans, fever, chills, headache, muscle aches, and a dry cough. Pneumonia is often evident on chest x-ray.
Chlamydiapsittaci, a gram-negative bacterium; the bacterium was previously known as Chlamydophila psittaci.
Since 2010, fewer than 10 confirmed cases are reported in the United States each year. More cases may occur that are not correctly diagnosed or reported.
Endocarditis, hepatitis, and neurologic complications may occasionally occur. Severe pneumonia requiring intensive-care support may also occur. Fatal cases have been reported but are rare.
Birds are the natural reservoirs of C. psittaci and infection is usually acquired by inhaling dried secretions from infected birds. The incubation period is 5 to 19 days. Although all birds are susceptible, pet birds (parrots, parakeets, macaws, and cockatiels) and poultry (turkeys and ducks) are most frequently involved in transmission to humans. Personal protective equipment (PPE), such as gloves and appropriate masks, should be used when handling birds or cleaning their cages.
Bird owners, aviary and pet shop employees, poultry workers, and veterinarians. Outbreaks of psittacosis in poultry processing plants have been reported.
Tetracyclines are the treatment of choice.
Psittacosis is a reportable condition in most states.
Annual incidence varies considerably because of periodic outbreaks. A decline in reported cases since 1988 may be the result of improved diagnostic tests that distinguish C. psittaci from more common C. pneumoniae infections.
Diagnosis of psittacosis can be difficult. Serologic tests are often used to confirm a diagnosis, but antibiotic treatment may prevent an antibody response, thus limiting diagnosis by serologic methods. Infected birds are often asymptomatic. Tracebacks of infected birds to distributors and breeders often is not possible because of limited regulation of the pet bird industry.
Characterize new and rapid diagnostic tests for human and avian psittacosis, and determine value of screening flocks for avian psittacosis to prevent human infection.
Kuo CC, Stephens RS, Bavoil PM, Kaltenboeck B. Genus Chlamydia Jones, Rake and Stearns 1945, 55. In Krieg NR, Staley JT, Brown DR, et al., editors. 2nd ed. Bergey’s Manual of Systematic Bacteriology: Volume 4. New York (NY): Springer-Verlag; 2011:846–65.