You are here: Home / Rare Disease Information / Rare Disease Database

Search Rare Diseases

Enter a disease name or synonym to search NORD's database of reports.

0-9 - A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - Q - R - S - T - U - V - W - X - Y - Z


NORD is very grateful to Charlotte A. Gaydos, M.S., M.P.H, Dr. P.H., Professor of Medicine, Johns Hopkins University, Division of Infectious Diseases, International STD and Biothreat Research Laboratory, for assistance in the preparation of this report.

Synonyms of Psittacosis

  • ornithosis
  • parrot fever

Disorder Subdivisions

  • No subdivisions found.

General Discussion

Psittacosis is an uncommon infectious disease that is most often transmitted to humans through exposure to infected birds, especially parrots, cockatiels, parakeets and similar pet birds. Psittacosis can affect the lungs and may cause inflammatory illness of the lungs (pneumonia). Additional common symptoms include fever, muscle pain (myalgia), headaches, and a dry cough.

Psittacosis is caused by infection with the bacterium, Chlamydia psittaci, and may also be known as ornithosis. It is rare among humans. People who own birds as pets are most likely to be affected by psittacosis. In addition, psittacosis may affect people who work in environments with birds that may be carriers of the infection such as pet store workers, farmers, veterinarians and ranchers.


The symptoms and severity of psittacosis can vary greatly. Some individuals may not develop any symptoms (asymptomatic) or only have a very mild infection; others can develop serious widespread infection that affects several organ systems of the body. The incubation period, which is the time between exposure to the bacterium to symptom development, is anywhere from five to 15 days. The onset of symptoms may be abrupt or gradual (insidious). The associated symptoms tend to be nonspecific and common to many different conditions.

Affected individuals may develop fever, chills, muscle pain (myalgia), headaches, and a general feeling of poor health (malaise). Pneumonia commonly occurs and, in some cases, can be severe. Breathing (respiratory) abnormalities may develop including a dry, nonproductive cough, difficulty breathing (dyspnea), a sore throat, and, in rare cases, chest pain. Frequent nosebleeds (epistaxis) and abnormal enlargement of the liver and spleen (hepatomegaly) are also common findings.

Although the lungs is the organ most often affected by psittacosis, the disease can potentially affect many organ systems in the body including the gastrointestinal tract, heart, liver, skin and central nervous system. Associated symptoms may include nausea and vomiting, abdominal pain, an abnormally slow heart rate (bradycardia), inflammation of the thin membrane (pericardium) that surrounds the heart (pericarditis), inflammation of the thin membrane (endocardium) lining the inside of the heart (endocarditis), inflammation of the liver (hepatitis) causing yellowing of the skin and eyes (jaundice), a rash on the face, severe headaches and a sensitivity to light (photophobia).


Psittacosis is caused in humans by exposure to the bacterium, Chlamydia psittaci, which is most often transmitted to humans from infected birds, especially parrots and poultry, especially turkeys.

Most infections occur from handling of infected birds themselves or by working in areas where such birds are kept or butchered (occupational exposure). Anyone in contact with an infected bird is at risk of psittacosis. However, cases have occurred in pet store workers, veterinarians, ranchers, and breeders of parrots, parakeets, love-birds, and macaws. Poultry workers handling the insides (viscera) of butchered turkeys also run a high risk of contracting the disease from blood and tissue. Another source of infection is the dried feces of birds and poultry and the dust from feathers and cages. Protective gloves and masks can often prevent transmission of the disease to these workers.

The respiratory system is the most likely manner through which individuals are affected. Individuals inhale airborne organisms either from dried droppings or respiratory secretions from infected birds.

The infected birds may be outwardly ill, or may show no signs of illness. Other animals such as cows, goats and sheep can be infected by the bacterium and can potentially transmit infection to humans. Human-to-human transmission is extremely rare, but has occurred and is usually associated with more severe symptoms than bird (avian)-to-human transmission.

Affected Populations

Psittacosis affects males and females in equal numbers. Anyone who handles an infected bird is at risk of developing psittacosis. Since the disease can become epidemic in animals, discovery of a single case of the disease should be reported to local public health authorities. The number of report cases of psittacosis in the United States has varied, ranging from 50 to 200 per year. Many researchers believe the disorder is under-diagnosed and the true number of cases that occur per year is unknown.

The disease was first was first described in the medical literature in 1879. The term, psittacosis, which is derived from the Greek word for parrot, was first used to describe this disease in 1892. Many physicians prefer the term ornithosis, which indicates that the disease can spread by more than just birds of the parrot family.

Related Disorders

Symptoms of the following disorders can be similar to those of psittacosis. Comparisons may be useful for a differential diagnosis.

Brucellosis is an infectious disease that affects livestock and may be transmitted to humans. It is rare in the United States, but occurs more frequently in other parts of the world. The disorder is caused by one of four different species of bacteria that belong to the genus Brucella. Initial symptoms of infection may be nonspecific including fevers, muscle pain, headache, loss of appetite, profuse sweating, and physical weakness. In some cases, the symptoms occur suddenly (acute), whereas, in others, symptoms may develop over the course of a few months. If brucellosis is not treated, the disease may take months to resolve once appropriate therapy is begun. Brucellosis may be confined to a certain area of the body (local) or have serious widespread complications that affect various organ systems of the body including the central nervous system. Brucellosis may be prevented if people drink only pasteurized cow and goat's milk. Pasteurization kills the bacteria that cause the disease. However, farmers and people exposed to butchered meat may also be affected by brucellosis. (For more information on this disorder, choose "brucellosis" as your search term in the Rare Disease Database.)

Tularemia is a rare infectious disease that most often affects small mammals such as rabbits, rodents and hares. It is highly infectious and is most often transmitted to humans by handling an infected animal or being bit by an infected tick or fly. People have not been known to transmit the infection to others. The disease is caused by the bacterium Francisella tularensis. The severity of tularemia varies greatly. Some cases are mild and self-limiting; others may have serious complications, and a small percentage (about 2 percent) may become life-threatening. (For more information on this disorder, choose "tularemia" as your search term in the Rare Disease Database.)

Psittacosis must be differentiated from other, more common causes of fever, chronic fatigue, weakness, and other nonspecific flu-like symptoms. These causes include other infectious diseases and various autoimmune diseases. Some specific conditions that may cause symptoms similar to psittacosis include Q fever, influenza, legionellosis, viral pneumonia, bacterial pneumonia, infective endocarditis, and tuberculosis. (For more information, choose the specific disorder name as your search term in the Rare Disease Database.)

Standard Therapies

The diagnosis of psittacosis is made based upon a thorough clinical evaluation, a detailed patient history, identification of characteristic findings and a variety of specialized tests such as specialized blood tests that reveal characteristic antibodies, produced by the body in response to psittacosis infection. Antibodies are specialized proteins produced by the body to fight off foreign material such as bacteria.

Antibiotic therapy is the primary treatment for individuals with psittacosis. Tetracycline and doxycycline are usually the first medications used. Most individuals respond within 24 to 72 hours. Erythromycin may be recommended for children or pregnant women. In rare cases, individuals have been treated with chloramphenicol.

Since the disease can become epidemic in animals, discovery of a single case of the disease should be reported to local public health authorities. The treatment of psittacosis in birds is important to avoid further transmission.

Investigational Therapies

Information on current clinical trials is posted on the Internet at All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Tollfree: (800) 411-1222
TTY: (866) 411-1010

For information about clinical trials sponsored by private sources, contact:

Psittacosis Resources



Bennett JC, Plum F, eds. Cecil Textbook of Medicine. 20th ed. Philadelphia, PA: W.B. Saunders Co; 1996:1725.

Mandell GL, Bennett JE, Dolan R. Eds. Mandell, Douglas and Bennett’s Principles and Practice of Infectious Diseases. 4th ed. Churchill Livingstone Inc. New York, NY; 1995:1693-1695.

Heddema ER, van Hannen EJ, Duim B, et al. An outbreak of psittacosis due to Chlamydophila psittaci genotype A in a veterinary teaching hospital. J Med Microbiol. 2006;55:1571-157.

Greco G, Corrente M, Martella V. Detection of Chlamydophila psittaci in aymptomatic animals. J Clin Microbiol. 2005;43:5410-5411.

Telfer BL, Moberley SA, Hort KP, et al. Probable psittacosis outbreak linked to wild birds. Emerg Infect Dis. 2005;11:391-397.

Madico, G., T.C. Quinn, J. Boman, C.A. Gaydos. Touchdown enzyme time release
polymerase chain reaction (TETRA-PCR) for the detection of C. pneumoniae, C. trachomatis, and C. psittaci using the 16S rRNA gene. J. Clin. Microbiol. 38:1085-1093, 2000.

Lessnau KL. Arjomand F. Psittacosis. Emedicine Journal, May 2 2006. Available at: Accessed on: February 6, 2008.

Centers for Disease Control and Prevention. Psittacosis. February 7, 2006. Available at: Accessed On: February 6, 2008.

The information in NORD’s Rare Disease Database is for educational purposes only. It should never be used for diagnostic or treatment purposes. If you have questions regarding a medical condition, always seek the advice of your physician or other qualified health professional. NORD’s reports provide a brief overview of rare diseases. For more specific information, we encourage you to contact your personal physician or the agencies listed as “Resources” on this report.

Report last updated: 2008/11/12 00:00:00 GMT+0

0-9 - A - B - C - D - E - F - G - H - I - J - K - L - M - N - O - P - Q - R - S - T - U - V - W - X - Y - Z

NORD's Rare Disease Information Database is copyrighted and may not be published without the written consent of NORD.

Copyright ©2015 NORD - National Organization for Rare Disorders, Inc. All rights reserved.
The following trademarks/registered service marks are owned by NORD: NORD, National Organization for Rare Disorders, the NORD logo, RareConnect. .