Health Services

Questions about Legionnaires’ disease

Frequently Asked Questions about Legionnaires' disease


What is Legionnaires' disease? Legionnaires' disease (or Legionellosis) is a type of pneumonia. It is caused by bacteria (Legionella) that are found naturally in the environment, usually in water. The bacteria grow best in warm water, in areas such as hot tubs, cooling towers, hot water tanks, large plumbing systems and decorative fountains. They do not seem to grow in car or window air-conditioners.

Is Legionnaires' disease new? No. The disease was named in 1976 when American Legion members who attended a Philadelphia convention suffered from an unusual pneumonia (lung infection).

Is Legionnaires' disease contagious? Legionnaires' disease is not spread from person to person. People get sick by breathing in water vapor containing the bacteria. The bacteria are not spread from one person to another person.

Who is at risk? Groups at high risk include people who are middle-aged or older -especially cigarette smokers- people with chronic lung disease or weakened immune systems and people who take medicines that weaken their immune systems (immunosuppressive drugs).

What should I do if I think I have been exposed to Legionnaires' disease? Most people exposed to the bacteria do not become ill. If you have reason to believe you were exposed to the bacteria, talk to your healthcare professional or call your local health department.* Be sure to mention if you have traveled in the last two weeks. If you have flu-like symptoms, seek medical attention, especially if you have a medical condition that affects your breathing, like emphysema, or if you are a smoker.

What are the symptoms of Legionnaires disease? Symptoms are like the flu and can include fever, chills, muscle aches and cough. Some people may also have headaches, fatigue, loss of appetite, confusion or diarrhea.

What is the treatment for Legionnaires' disease? The disease is treated with antibiotics. Most people get better with early treatment, although they may need to be hospitalized. Some people may get very sick or even die from complications of the disease. That's why it is important to seek medical help if you develop symptoms.

Additional Information on Legionnaires' disease can be found here:

*To speak with a Suffolk County healthcare professional about possible exposure to Legionella bacteria, call 631-854-0333.