Skip Ribbon Commands
Skip to main content
Health Issues

Legionnaires Disease

Legionnaires disease, also called legionellosis, is caused by the bacteria Legionella pneumophila and related species. These organisms have been found in water delivery systems. The infection can be caught by inhaling mists from water contaminated with the germs. Outbreaks have been traced to contaminated whirlpool spas, humidifiers, and air conditioning cooling towers and have occurred in hospitals, hotels, and cruise ships. The incubation period for legionnaires disease is 2 to 10 days.

The disease and the organism that causes legionnaires disease were identified and got their names from the first known outbreak, at an American Legion convention held at a Philadelphia, PA, hotel in 1976.

A related disease called Pontiac fever is caused by the same Legionella species. It is a milder, less serious infection with an incubation period of 1 to 2 days.

Signs and Symptoms

The symptoms of legionnaires disease can range from mild to severe. A form of pneumonia is a key component of the disease and may have symptoms that include

  • Fever
  • Cough
  • Chills
  • Muscle aches
  • Progressive breathing difficulties

These symptoms can get worse for the first few days of the infection before the patient begins to get better. People at greatest risk of contracting legionnaires disease are the elderly and those with suppressed immune systems.

Children rarely get the infection and when they do, their illness is usually mild or they may have no symptoms at all. Pontiac fever causes flu-like symptoms such as muscle aches and a fever, but there are no signs of pneumonia.

When To Call Your Pediatrician

Call your pediatrician if your child develops breathing problems.

How Is the Diagnosis Made?

Your pediatrician can collect a sample of the secretions from your child’s respiratory tract and send it to the laboratory for analysis. Urine tests can also be performed to look for the bacteria, as well as antibody tests that can be conducted on blood samples.


Antibiotics such as azithromycin are used to treat legionnaires disease.

No treatment is needed for Pontiac fever, which goes away on its own in 2 to 5 days.

What Is the Prognosis?

The most serious cases of legionnaires disease lead to respiratory failure and death, especially in the elderly or people with weak immune systems. These deaths occur in 5% to 15% of cases.

    Last Updated
    Adapted from Immunizations and Infectious Diseases: An Informed Parents Guide (Copyright © 2006 American Academy of Pediatrics) and updated 2011
    The information contained on this Web site should not be used as a substitute for the medical care and advice of your pediatrician. There may be variations in treatment that your pediatrician may recommend based on individual facts and circumstances.
    Follow Us