• Legionnaires' Disease

    (Legionnaires' Pneumonia)


    Legionnaires' disease is a lung infection. It is a form of pneumonia. It got its name from an outbreak at the American Legionnaires Convention in 1976.


    This disease is caused by specific bacteria. The bacteria are most often found in sources of standing water. It may be found in cooling towers, HVAC systems, and air conditioners.
    Legionnaires' disease can be contracted by breathing water vapor from a standing water source that contains the bacteria.
    The Lungs
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    The infection does not move from one person to another.

    Risk Factors

    Factors that may increase your chance of Legionnaires' disease include:
    • Advanced age
    • Smoking
    • Chronic lung disease
    • Weakened immune system
    • Kidney failure
    • Diabetes
    • Taking cortisone or other immunosuppressive drugs
    • History of organ transplant


    Symptoms may include:
    • Fatigue
    • Fever (often high)
    • Chills and muscle aches
    • Cough
    • Headache


    Your doctor will ask about your symptoms and medical history. A physical exam will be done.
    Your doctor may need pictures of your chest. This can be done with a chest x-ray.
    Your doctor may need tests of your bodily fluids. This can be done with:
    • Urine tests
    • Sputum tests
    • Blood tests


    This disease is usually treated with antibiotics.


    Proper design, maintenance, and cleaning of high-risk areas can reduce the risk of spreading the disease. This includes any area with standing water.


    Centers for Disease Control and Prevention http://www.cdc.gov

    National Institute of Environmental Health Sciences http://www.niehs.nih.gov


    Capital Health Nova Scotia http://www.cdha.nshealth.ca

    Manitoba Health http://www.gov.mb.ca


    Arcavi L, Benowitz NL. Cigarette smoking and infection. Arch Intern Med. 2004;164(20):2206-2216.

    Community-acquired pneumonia in adults. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T115170/Community-acquired-pneumonia-in-adults. Updated August 15, 2016. Accessed September 28, 2016.

    Legionnaires' disease. Occupational Safety and Health Administration website. Available at: https://www.osha.gov/dts/osta/otm/legionnaires/index.html. Accessed December 31, 2012.

    Legionnaires' disease. Patient UK website. Available at: http://patient.info/health/legionnaires-disease-leaflet. Accessed December 31, 2012.

    Legionella infections. EBSCO DynaMed Plus website. Available at: http://www.dynamed.com/topics/dmp~AN~T904756/Legionella-infections. Updated May 20, 2016. Accessed September 28, 2016.

    Legionella (Legionnaires' disease and Pontiac fever). Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/legionella/about/index.html. Updated June 1, 2011. Accessed December 31, 2012.

    Top 10 things every clinician needs to know about Legionellosis. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/legionella/clinicians.html. Updated June 1, 2011. Accessed December 31, 2012.

    Revision Information

    • Reviewer: EBSCO Medical Review Board David L. Horn, MD
    • Review Date: 03/2017
    • Update Date: 05/02/2014
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