Legionella bacteria can cause a serious type of pneumonia (lung infection) called Legionnaires’ disease. Legionnaires’ disease is not contagious and almost never spreads from person to person. Most healthy people do not get Legionnaires’ disease after being exposed to Legionella. Legionella bacteria can also cause a less serious illness called Pontiac fever.

People can get sick when they breathe in small droplets of water or accidentally swallow water containing Legionella into the lungs. Legionella occurs naturally in freshwater environments, like lakes and streams. It can become a health concern when it grows and spreads in buildings’ water systems that are not properly maintained. Outbreaks are often linked to large or complex water systems, like those found in hospitals, hotels and cruise ships. The most common sources of infection are from showers, air conditioning cooling towers, decorative fountains and hot tubs.

Learn more at CDC


Legionnaires' disease is similar to other types of pneumonia with symptoms that include:

  • Cough

  • Shortness of breath

  • Fever

  • Muscle aches

  • Headaches

Symptoms usually begin two to 14 days after being exposed to the bacteria, but it can take longer. The disease can be treated with antibiotics. Most people who get sick need care in a hospital but make a full recovery. However, about one in 10 people who get it will die from the infection. 

Pontiac fever is a milder infection and symptoms are usually fever and muscle aches. They can begin between a few hours to three days after being exposed. The illness usually lasts less than a week and goes away without requiring treatment. 

People at Increased Risk

Certain risk factors can increase your chances of getting sick from Legionnaires' disease, including:

  • Being 50 years or older 

  • Currently or formerly smoking tobacco or other products 

  • Having chronic lung disease

  • Having a weakened immune system 

Pontiac fever most commonly occurs in people who are otherwise healthy.

What Vermonters Can Do

  • Talk to your health care provider if you believe you might have been exposed to Legionella and have symptoms. Be sure to mention if you have used a hot tub, spent any nights away from home, or stayed in a hospital in the last two weeks. 

  • The key to preventing Legionnaire’s disease is to reduce the risk of Legionella growth and spread. Building owners and managers can develop a water management program to reduce their building’s risk for growing and spreading the bacteria.


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