Legionnaires Disease

What is Legionnaires' disease?

Legionnaires' disease is a type of pneumonia (lung infection) caused by bacteria called Legionella.

Where do Legionella bacteria come from?

Legionella bacteria are found naturally in the environment, usually in water. The bacteria grow best in warm water, like the kind found in hot tubs, cooling towers, hot water tanks, large plumbing systems, or parts of the air-conditioning systems of large buildings.

How do people get Legionnaires' disease?

People get Legionnaires' disease when they breathe in a mist or vapor (small droplets of water in the air) that has been contaminated with the bacteria. One example might be from breathing in the steam from a whirlpool spa that has not been properly cleaned and disinfected. Other infections have been linked to aerosol sources such as cooling towers (air-conditioning units from large buildings) and water used for drinking and bathing. The bacteria are NOT spread from one person to another person.

Who is most at risk?

People most at risk of getting sick from the bacteria are older people (usually 65 years or older), people who smoke or have chronic lung disease (like emphysema), and those who have weak immune systems from cancer, diabetes, kidney failure, medications, or other medical conditions.

How can I protect myself and family?

There are no vaccines that can prevent Legionnaires' disease.

Instead, the key to preventing Legionnaires' disease is to make sure that building owners and managers maintain building water systems in order to reduce the risk of Legionella growth and spread. Examples of building water systems that might grow and spread Legionella include:

CDC developed a toolkit to help building owners and managers develop and implement a water management program to reduce their building's risk for growing and spreading Legionella.

For private residence homes the CDC has developed a guide on how to prevent water borne germs home

What are the symptoms of Legionnaires' disease?

How is Legionnaires' disease diagnosed?

Most people with Legionnaires' disease get pneumonia (lung infection) since the Legionella bacteria grow and thrive in the lungs. Pneumonia is confirmed either by chest x-ray or clinical diagnosis. Several laboratory tests can be used to detect the Legionella bacteria in the body. CDC recommends that clinicians collect both a urine specimen (for a urine antigen test) as well as a lower respiratory tract specimen such as sputum for bacterial culture or PCR (polymerase chain reaction).

How serious is it? What is the treatment?

Legionnaires' disease can be very serious and can be fatal in 5 percent to 30 percent of cases. Most people can be treated successfully with specific antibiotics (drugs that kill bacteria in the body).


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