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    Legionnaire disease

    Legionella pneumonia; Pontiac fever

    Legionnaire disease is an infectionof the lungs and airwayscaused by Legionella bacteria.


    The bacteria that cause Legionnaire disease have been found in water delivery systems. They can survive in the warm, moist, air conditioning systems of large buildings, including hospitals.

    Most cases are caused by the bacteriaLegionella pneumophila. The rest of the cases are caused by other Legionella species.

    Spread of the bacteria from person to person has not been proven.

    Most infections occur in middle-age or older people. Inrare cases,children can get the infection. When they do, the disease is less severe.

    Risk factors include:

    • Alcohol abuse
    • Cigarette smoking
    • Chronic illnesses such as kidney failure or diabetes
    • Weakened immune system, such as during cancer treatment or taking steroid medicines
    • Long-term (chronic) lung disease, such as COPD
    • Long-term use of a breathing machine (ventilator)
    • Medicines that suppress the immune system, including chemotherapy and steroid medications
    • Older age


    Symptoms tend to get worse during the first 4 - 6 days. Theymost oftenimprove in another 4 - 5 days.

    Symptoms may include:

    • Chest pain
    • Cough that does not produce much sputum or mucus (dry cough)
    • Coughing up blood
    • Diarrhea, nausea, vomiting, and abdominal pain
    • Fever
    • General discomfort, uneasiness, or ill feeling (malaise)
    • Headache
    • Joint pain
    • Loss of energy
    • Muscle aches and stiffness
    • Problems with balance
    • Shaking chills
    • Shortness of breath

    Exams and Tests

    The health care provider will perform a physical exam. Abnormal sounds called crackles may be heardwhen listening to the chest with a stethoscope.

    Tests that may be done include:

    • Arterial blood gases
    • Blood culturesBronchoscopy
    • Chest x-ray
    • Complete blood count (CBC), including white blood cell countESR (sed rate)
    • Liverblood tests
    • Tests andcultures on sputum to identifythe Legionella bacteria
    • Urine tests to check for Legionella pneumophila bacteria


    Antibiotics are used to fight the infection. Treatment is started as soon as Legionnaire disease is suspected, without waiting for results of any lab test.

    Other treatments may include receiving fluids and oxygen, which is given through a mask or breathing machine.

    Outlook (Prognosis)

    Legionnaire disease can be life-threatening. The risk of dying is higher in patients who:

    • Have chronic diseases
    • Become infected while in the hospital

    When to Contact a Medical Professional

    Make an appointment with your health care provider if you have any type of breathing problem.


    Edelstein PH, Ciancioti NP. Legionella. In: Mandell GL, Bennett JE, Dolin R, eds. Principles and Practice of Infectious Diseases. 7th ed. Philadelphia, PA: Elsevier Churchill-Livingstone; 2009:chap 232.

    Torres A. Menendez R, Wunderink R. Pyrogenic bacterial pneumonia and lung abscess. In: Mason RJ, Broaddus VC, Martin TR, et al., eds.Murray & Nadel's Textbook of Respiratory Medicine. 5th ed. Philadelphia, PA: Elsevier Saunders; 2010:chap 32.


    • Legionnaires' disease or...


      • Legionnaires' disease or...


      A Closer Look

        Talking to your MD

          Self Care

            Tests for Legionnaire disease

              Review Date: 1/24/2013

              Reviewed By: Denis Hadjiliadis, MD, Assistant Professor of Medicine, Division of Pulmonary, Allergy and Critical Care, University of Pennsylvania, Philadelphia, PA. Also reviewed by A.D.A.M. Health Solutions, Ebix, Inc., Editorial Team: David Zieve, MD, MHA, David R. Eltz, Stephanie Slon, and Nissi Wang.

              The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed medical professional should be consulted for diagnosis and treatment of any and all medical conditions. Links to other sites are provided for information only -- they do not constitute endorsements of those other sites. © 1997- A.D.A.M., Inc. Any duplication or distribution of the information contained herein is strictly prohibited.

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