Legionnaires’ Disease

Legionnaires’ disease is a type of pneumonia. It is caused by bacteria (Legionella) that grow in warm water. Legionnaires’ disease causes flu-like symptoms, and complications from the disease can be fatal.

People who inhale mist that contains Legionella bacteria can get sick. Sources of water with Legionella contamination may include cooling towers, showers and hot tubs. Most people who are exposed to the bacteria do not develop Legionnaires’ disease, and it is not contagious — you cannot get it from someone else. You cannot get Legionnaires’ disease by drinking the water.

You are at a high risk for Legionnaires’ disease if you:

  • Are 50 years old or older
  • Smoke
  • Have a chronic lung disease
  • Have a weakened immune system
  • Take medicines that weaken your immune system


Legionnaires’ disease symptoms include fever, chills, muscle aches and a cough. You may also have headaches, fatigue, loss of appetite, confusion or diarrhea.

If you have these symptoms, seek medical attention right away. You are especially at risk if you are a smoker or have a medical condition that affects your breathing. Tell your health care provider you are worried about Legionnaires’ disease.


There is no vaccine or medicine that can prevent Legionnaires’ disease. The best way to prevent it is through the proper maintenance of water systems where Legionella may grow.

In NYC, building owners are required to register cooling towers. They also need to routinely test the water for the presence of Legionella. You can look up results of Health Department inspections of cooling tower systems by building address or building identification number (BIN).

The Health Department investigates clusters of Legionnaires’ disease cases to find the source of the contamination in order to prevent other people from getting sick. When two or more confirmed cases of Legionnaires’ disease within a 12-month period are associated with the same building with a shared hot water system, the Health Department will conduct a building evaluation.

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