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Ornithosis; Chlamydia psittaci

Psittacosis is an infection caused by Chlamydophila psittaci, a type of bacteria found in the droppings of birds. Birds spread the infection to humans.

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  • Causes

    Psittacosis is a rare disease: 100 - 200 cases are reported each year in the United States.

    Bird owners, pet shop employees, persons who work in poultry processing plants, and veterinarians are at increased risk for this infection. Typical birds involved are parrots, parakeets, and budgerigars, although other birds have also caused the disease.

  • Symptoms

    • Blood-tinged sputum
    • Dry cough
    • Fatigue
    • Fever and chills
    • Headache
    • Joint aches
    • Muscle aches (especially in the head and neck)
    • Shortness of breath
  • Exams and Tests

    The health care provider will hear abnormal lung sounds such as crackles and decreased breath sounds when listening to the chest with a stethoscope.

    Tests include:

    • Antibody titer (rising titer over time is a sign of infection)
    • Blood culture
    • Blood gases
    • CT scan of the chest
    • Sputum culture
    • X-ray of the chest
  • Treatment

    The infection is treated with antibiotics. Doxycycline is used first. Other antibiotics that may be prescribed include:

    • Macrolides
    • Fluoroquinolones
    • Other tetracycline antibiotics

    Note: Tetracycline and doxycycline by mouth is usually not prescribed for children until after all their permanent teeth have started to grow in or to pregnant women. The medicine can permanently discolor teeth that are still forming.

  • Outlook (Prognosis)

    Full recovery is expected.

  • Possible Complications

    • Brain involvement
    • Decreased lung function as a result of the pneumonia
    • Heart valve infection
    • Inflammation of the liver (hepatitis)
  • When to Contact a Medical Professional

    Antibiotics are needed to treat this infection. If you develop symptoms of psittacosis, call your health care provider.

  • Prevention

    Avoid exposure to birds that may carry this bacteria, such as imported parakeets. Medical problems that lead to a weak immune system increase your risk for this disease and should be treated appropriately.

Related Information

  SystemicPneumonia - adults...Hepatitis     Pneumonia


Torres A. Pyogenic bacterial pneumonia and lung abscess. In: Mason RJ, Broaddus CV, Martin TR, et al. Murray & Nadel's Textbook of Respiratory Medicine. 5th ed. Philadelphia, Pa: Saunders Elsevier; 2010:chap 32.

Limper AH. Overview of pneumonia. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 97.


Review Date: 8/30/2012  

Reviewed By: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine. Denis Hadjiliadis, MD, Assistant Professor of Medicine, Division of Pulmonary, Allergy and Critical Care, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M. Health Solutions, Ebix, Inc.

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