Legionellosis is a serious lung infection caused by the bacteria Legionella. This infection is also known as Legionnaires’ Disease. The bacteria are found naturally in freshwater, like lakes and streams. The bacteria can also grow and spread in:

  • Showerheads and sinks
  • Cooling towers
  • Hot tubs
  • Fountains
  • Large plumbing systems

On this page

  • Spread of Legionella
  • Signs and Symptoms of Legionellosis
  • Prevention of Legionellosis
  • Resources for the Public

  • Spread of Legionella

    Legionella bacteria
    Legionella bacteria

    People can get sick when small drops of water with the bacteria get into the air. People then breathe them in and the bacteria gets in their lungs. The bacteria cannot spread from one person to another.
    Most healthy people exposed to the bacteria do not get sick. Being 50 years or older or having certain risk factors can increase your chances of getting sick. These include:

    • Being a current or former smoker
    • Having chronic lung disease
    • Having a weakened immune system from diseases like cancer, diabetes, or kidney failure
    • Taking medications that weaken your immune system


    Signs and Symptoms of Legionellosis

    Signs and symptoms include:

    • Cough
    • Shortness of Breath
    • Fever
    • Muscle Aches
    • Headaches

    Other symptoms include diarrhea, nausea, and confusion. Symptoms usually start 2 to 14 days after breathing in the bacteria.


    Prevention of Legionellosis

    Routine home maintenance can prevent growth of the bacteria.

    • Water Heaters: Most manufacturers recommend that water heaters be flushed every year. This helps reduce the risk of bacteria growth. Electric water heaters are more likely than gas water heaters to have bacteria. Flushing should be done with caution by a qualified plumber.
    • Showers: Remove the shower head and manually clean it. This can be done by soaking it in a mixture of 1 tablespoon household bleach to 1 gallon of water for about two hours.
    • Humidifiers: Humidifiers should be cleaned and disinfected regularly. Always unplug the humidifier first. Clean the inside using a mixture such as 1 tablespoon household bleach to 1 gallon of water, and dry. Follow the manufacturer’s instructions for cleaning.
    • CPAP Machines and Nebulizers: Use distilled water only and clean regularly. Follow the manufacturer’s instructions for cleaning.


    Resources for the Public