Legionnaires' disease is a serious type of pneumonia caused by Legionella bacteria. People catch it by breathing in mist that contains the bacteria; in general it does not spread from person to person. Most healthy people who are exposed don't get sick, but some people are at higher risk — and it can kill. Antibiotics treat it.
Where the name comes from
Legionella was discovered after an outbreak in 1976 among people who had attended an American Legion convention in Philadelphia. The pneumonia they suffered came to be called Legionnaires' disease.
What Legionella causes
| Illness | What it is |
|---|---|
| Legionnaires' disease | a severe pneumonia |
| Pontiac fever | a mild illness that can include fever, muscle aches and headaches |
| Other infections (rare) | outside the lungs, such as heart or wound infections |
Symptoms
Symptoms usually start 2 to 14 days after exposure, though it can take longer. They look like other pneumonias:
- cough
- fever
- headaches
- muscle aches
- shortness of breath
Confusion, diarrhea or nausea can also occur.
If you are concerned, find out whether you are among the people at higher risk and talk to your healthcare provider. CDC explains more about causes and spread.
How it's diagnosed
A chest x-ray can show whether someone has pneumonia. Finding out whether Legionella is behind it takes other tests:
- a urine test
- a laboratory test on sputum (phlegm) or on a washing from the lung
When someone is diagnosed, the healthcare provider or laboratory reports the case to the local or state health department. People can also report their own case to the health department of the state where they think they were exposed; the department decides whether to investigate. CDC keeps a directory of health departments.
Treatment and outlook
Legionnaires' disease needs treatment with certain antibiotics, and most cases are treated successfully; finding and treating it early improves the chances of recovery. Healthy people usually get better, but they often need hospital care.
It can lead to lung failure and death:
| Where the illness was caught | Share who die of complications |
|---|---|
| Overall | about 1 in 10 |
| During a stay in a healthcare facility | about 1 in 4 |
Prevention: stop Legionella growing and spreading
| Where | What to do |
|---|---|
| Buildings and public hot tubs | owners and managers can run a water management program to control Legionella — see About Legionella Control |
| At home | take steps against waterborne germs — see Preventing Waterborne Germs at Home |
| In vehicles | Legionella can grow in the windshield-washer tank, especially when it is filled with water. Use genuine windshield washer fluid and follow the manufacturer's recommendations where there are any — see NIOSH on Legionnaires' disease among commercial vehicle operators |
More from CDC
- Legionnaires' disease fact sheet and an infographic on how Legionella affects building water systems and people
- For building owners and managers: how to control Legionella
- For public health professionals: how to investigate Legionnaires' disease
Sources
Based on "About Legionnaires' Disease," Centers for Disease Control and Prevention; a work of the United States government in the public domain. A stock photograph is left out.
Licence: CC0 1.0 (public domain) · Adapted from www.cdc.gov
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