Legionnaires' Disease

Legionnaires' Disease

Specific prevention resources for the general public, healthcare providers, and businesses are located at the bottom of this page.

What is Legionnaires' Disease?

Legionnaires’ Disease (Legionellosis) is a respiratory infection (pneumonia) caused by bacteria called Legionella.

Who can get Legionnaires' Disease?

Anyone can get Legionnaires' Disease, but most people exposed to Legionella will not get sick.

Who is most at risk of getting Legionnaires' Disease?

People at highest risk are:

  • 50 years and older
  • Current or former smokers
  • Persons with a chronic lung disease or respiratory condition, such as emphysema or chronic obstructive pulmonary disease (COPD)
  • Persons with poor immune systems, such as people with cancer, diabetes, kidney disease, transplant recipients, and those taking certain medications such as tumor necrosis factor alpha inhibitors

Talk to your doctor to find out if you are at an increased risk for getting Legionnaires' Disease.

What are the symptoms of Legionnaires' Disease?

  • Fever (typically between 102-105 degrees)
  • Chills
  • Cough
  • Shortness of breath
  • Muscle aches 
  • Headache

Other common symptoms include:

  • Confusion
  • Nausea  
  • Diarrhea
  • Chest pain

How long after exposure do symptoms begin?

2-10 days after exposure, though it can take up to 2 weeks for symptoms to appear after exposure.

How is Legionnaires' Disease spread?

People get Legionnaires' Disease when they breathe in droplets of water in the air that contain the bacteria.  Common sources of exposure include:

  • Cooling towers (large building air conditioning systems)
  • Whirlpool spas and hot tubs
  • Hot water tanks
  • Decorative fountains
  • Showers

People can be exposed inside or outside of buildings.  Home and car air conditioners do not use water to cool the air, so they are not a risk for Legionella growth.

How long is a person contagious?

The bacteria are not spread from one person to another, so there is no contagious period.

Are there complications?

Legionnaires’ Disease can be very serious and can cause death in 10% to 25% of cases. Most healthy people usually recover.

Is there a treatment for Legionnaires' Disease?

The prompt diagnosis of Legionnaires’ Disease can save lives.  Antibiotics are used to treat Legionnaires’ Disease.

How can Legionnaires'​ Disease be prevented?

To prevent Legionnaires' Disease, make sure water systems in buildings are maintained.  Examples of water systems include cooling towers, large plumbing systems, hot tubs, and hot water tanks and heaters.

Talk to your doctor if you believe you were exposed to Legionella and develop symptoms such as fever, cough, chills, or muscle aches.

See below for specific prevention resources for the general public, healthcare providers, and businesses.

$Expand=File&$orderby=Order asc
Healthcare Providers/Clinicians,

​Because of increasing rates of Legionella pneumonia in Southeast Michigan, additional testing should be performed if Legionella pneumonia is clinically relevant in the differential diagnosis (positive risk screening or in a hospital for at least 48 hours).  Healthcare providers should order the urinary antigen test and a respiratory sputum panel with legionella culture if the clinical presentation is consistent with legionella.  If the urine antigen test is positive, continue both the standard respiratory cultures and legionella culture to determine strain.  If the urine antigen is negative but clinical picture is consistent with legionella, continue with cultures as well.  

Please note that with this increased rate of Legionella pneumonia, an additional indication for Legionnaires' Disease Testing in patients with pneumonia is:

  • Patients with pneumonia who have visited a healthcare facility (either as a visitor or as a patient) within the previous 21 days (lab, dentist, hospital, physician's office, etc.).

For more information about diagnosis, treatment, and prevention of Legionnaires’ disease visit: https://www.cdc.gov/legionella/clinicians.html

General Public,

Legionnaires' (LEE-juh-nares) disease is a very serious type of pneumonia (lung infection) caused by Legionella bacteria.

For more information about Legionnaires' Disease, including symptoms and prevention, visit: