How to Recognize and Treat Legionnaires' Disease

Legionnaires' disease is an illness caused by a type of bacteria called Legionella. The disease is a form of pneumonia (lung infection) usually found in the summer and early fall, although it can occur year round. Between 8,000- 18,000 people are hospitalized with Legionnaires' disease in the U.S. every year.


  1. 1
    Know who gets the disease. Those most at risk includes:
    • People 65 years of age or older.
    • Smokers.
    • Those who have a chronic lung disease, like emphysema.
    • People with weakened immune systems from diseases or who take drugs that can suppress the immune system.
  2. 2
    Understand how the disease is spread.
    • People get the disease when they breathe in small droplets of water in the air that has been contaminated with the bacteria. Examples of how this may occur include:

      • Inhaling the steam from a hot tub that has not been properly cleaned or disinfected.
      • Breathing the air of a large air-conditioning unit that has the bacteria in the system.
      • Being near someone who has the disease, especially through kissing and breathing in close to each other.
      • The inhalation of vapors from a whirlpool or heated wading pool contaminated with the bacteria.
  3. 3
    Recognize the symptoms of the infection. Look for:
  4. 4
    Be aware that symptoms usually begin 2-14 days after exposure to the bacteria. A milder form of the infection (caused by the same type of bacteria) is called Pontiac Fever. The symptoms are usually the same, however, there is no pneumonia.
  5. 5
    Know the treatment for the infection. The majority of cases can be successfully treated with antibiotics. People who are in good health will generally recover.
  6. 6
    Contact your doctor or local health department if you suspect you may have been exposed to the bacteria. If you traveled in the last two weeks before becoming ill, be sure to mention this to your doctor.


  • The bacteria can not spread from one person to another person.
  • Diagnosis of the disease is through the examination of lung X-rays, respiratory secretions (phlegm), urine specimen, or blood specimen.
  • The bacteria grow best in warm water. Examples include:

    • Hot tubs.
    • Cooling towers.
    • Hot water tanks.
    • Large plumbing systems, such as those found in hotels and on cruise ships.
    • Air-conditioning systems of large buildings.


  • This disease can be very serious and can cause death in up to 5%-30% of cases.
  • Prevention is key!

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Categories: Respiratory Health