About Legionnaires' Disease

What it is

Legionnaires' disease is a type of serious pneumonia caused by a type of bacteria called Legionella.

Types

Legionella most commonly causes one of two diseases:

• Legionnaires' disease is a type of severe pneumonia
• Pontiac fever is mild illness that can include fever, muscle aches, and headaches

Rarely, Legionella can cause infections outside of the lungs, such as heart or wound infections.

Symptoms

Legionnaires' disease symptoms usually develop 2 to 14 days after exposure to Legionella bacteria, but it can take longer.

The symptoms of Legionnaires' disease are similar to other types of pneumonia.

Symptoms include:

• Cough
• Fever
• Headaches
• Muscle aches
• Shortness of breath

Other symptoms, such as confusion, diarrhea, or nausea can also occur.

Risk factors

Most healthy people exposed to Legionella don't get sick. However, certain factors put people at increased risk for developing Legionnaires' disease.

Causes

A type of bacteria called Legionella causes Legionnaires' disease. People can get Legionnaires' disease when they breathe in mist that contains the bacteria.

Prevention

The key to preventing Legionnaires' disease is to reduce the risk of Legionella growth and spread.

In buildings and public hot tubs

Building owners and managers can use a water management program to help control Legionella.

At home

There are steps people can take to help protect themselves from waterborne germs in their home.

In motor vehicles

Legionella can grow in the windshield wiper fluid tank of a vehicle, particularly if the tank is filled with water. To prevent growth and spread of Legionella, only use genuine windshield cleaner fluid and follow the vehicle manufacturer recommendations, if available.

Testing and diagnosis

A chest x-ray can confirm if someone has pneumonia. Other tests are needed to see if Legionella is causing someone's pneumonia:

• Urine test
• Laboratory test that involves taking one of the following samples:
  • Sputum (phlegm)
  • Washing from the lung

Reporting cases

If someone is diagnosed with Legionnaires' disease, the healthcare provider or lab that did the testing will report the case to the local or state health department. People can also report their case by contacting the health department of the state where they believe they were exposed. The health department will determine if an investigation is needed. Find more information about how to contact health departments at CDC's health department directory.

Treatment and recovery

Legionnaires' disease requires treatment with certain antibiotics. Most cases of this illness can be treated successfully. Identifying and treating the illness early can increase the chances of getting better.

Healthy people usually get better after being sick with Legionnaires' disease, but they often need care in a hospital.

Complications

Possible complications of Legionnaires' disease include:

• Lung failure
• Death

About 1 out of every 10 people who gets sick with Legionnaires' disease will die due to complications from their illness. For those who get Legionnaires' disease during a stay in a healthcare facility, about 1 out of every 4 will die.

History

Legionella was discovered after an outbreak in 1976 among people who went to a Philadelphia convention of the American Legion. Those who were affected suffered from a type of pneumonia that eventually became known as Legionnaires' disease.

Resources

General resources

Fact sheet: Legionnaires' disease

Infographic: How Legionella affects building water systems and people

For professionals

How to control Legionella
For building owners and managers

How to investigate Legionnaires' disease
For public health professionals