Potential Bioterrorism Agent: Category B
Also known as: Parrott fever, Omithosis
Hospital: Report by IDSS, mail, facsimile, or phone
Lab: Report by IDSS, mail, facsimile, or phone
Physician: Report by mail, facsimile, or phone
Local Public Health Agency (LPHA): Report by IDSS, mail, facsimile, or phone. Follow-up required
Iowa Department of Public Health
Disease Reporting Hotline: (800) 362-2736
Secure Fax: (515) 281-5698
Chlamydia psittaci is the bacterium that causes psittacosis. It is an obligate intracellular parasite.
B. Clinical Description
Symptoms can include high fever, headache, rash, myalgia (muscle aches), chills, and upper or lower respiratory tract disease. A cough may or may not be present.
Onset of respiratory symptoms often seem milder than expected based on chest x-ray findings.
Complications such as systemic illness can occur with pneumonia. Human disease can be severe (including encephalitis and myocarditis), especially in untreated elderly people, although it is usually mild or moderate for others. Relapses of illness may occur. Occasionally fatal in untreated patients.
Common reservoirs C. psittaci is found primarily in psittacine birds (parrots, parakeets, macaws, love birds, and cockatoos); pigeons and some poultry (turkeys, geese and ducks) may also shed the infectious agent.
D. Modes of Transmission
Spread: Pet birds, especially psittacine birds are often implicated, especially when owners clean a cage with dried droppings. Occupational exposure can also occur when workers are exposed to areas with contaminated dust during clean up, repair or demolition. Laboratory infections have occurred as well. Farms or rendering plants may be a source of exposure for workers. Many seemingly healthy birds may shed the agent when stressed by crowding or transport. Dramatic outbreaks may occur in poultry packing plant workers.
Airborne: Human illness occurs from inhalation of the bacteria in dried droppings, secretions, and dust from feathers of infected birds.
Person-to-person: transmission (through paroxysmal coughing during acute illness) has only rarely been reported.
E. Incubation period
The incubation period for psittacosis can range from 1-4 weeks, but it is usually 7 - 14 days.
F. Period of Communicability or Infectious Period
Infected birds, including those that appear to be healthy, can be lifetime carriers or have continuous or intermittent shedding periods of weeks or even months. If humans are contagious at all, it is during paroxysmal coughing with acute illness.
Psittacosis occurs worldwide and in all seasons, with some increase in winter months owing to maintaining the agent in ambient air. Most human cases are sporadic and are usually confined within families. Human outbreaks of psittacosis occasionally occur in individual households, pet shops, aviaries, and avian exhibits in zoos. Outbreaks among birds can occur in poultry flocks or other groups of birds such as in pet stores. Quarantine of imported birds and treatment of birds with antibiotics reduces the risk of disease transmission from birds.
In Iowa no cases have been reported in the last 5 years.
H. Bioterrorism Potential
Category B Agent: Psittacosis has been identified as a potential category B bioterrorism agent as a respiratory threat.
I. Additional Information
The Council of State and Territorial Epidemiologists (CSTE) surveillance case definitions Psittacosis can be found at:
CSTE case definitions should not affect the investigation or reporting of a case that fulfills the criteria in this chapter. (CSTE case definitions are used by the state health department and the CDC to maintain uniform standards for national reporting.)
American Academy of Pediatrics. 2006 Red Book: Report of the Committee on Infectious Diseases, 27th Edition. Illinois, American Academy of Pediatrics, 2006.
Heymann, David L., ed., Control of Communicable Diseases Manual, 20th Edition. Washington, DC, American Public Health Association, 2015.
National Association of State Public Health Veterinarians. Compendium of Measures to Control Chlamydia psittaci Infection among Humans (Psittacosis) and Pet Birds (Avian Chlamydiosis), 2004. National Association of State Public Health Veterinarians, Inc., 2004.