Legionnaires’ Disease

What is Legionnaires’ Disease?

Legionnaire’s Disease is a form of atypical pneumonia caused by Legionella bacteria. It is normally spread by breathing in mist that contains the bacteria. The bacterium can be found naturally in fresh water but can also contaminate hot water tanks, hot tubs, and the cooling towers of large air conditioners.

Legionnaire’s disease is hard to diagnose because it shares signs and symptoms with other conditions like Pontiac fever which goes away without the need of treatment. The disease is named after the outbreak where it was first identified, the 1976 American Legion convention in Philadelphia. Most people who become exposed don’t become infected and it’s not typically transmitted from person to person.

Individuals at greater risk for contracting Legionnaire’s disease include older people, those with a history of lung disease, and those with poor immune function. It’s important to note that the disease can be fatal. Around 10% of those infected die. Every year in the United States eight to eighteen thousand people are hospitalized because of Legionnaire’s disease.

What are the Symptoms of Legionnaires’ Disease?

Legionnaires’ Disease can cause a cough, high fever, shortness of breath, headaches, muscle pains, vomiting, nausea, tiredness, loss of appetite, coughing up blood, and diarrhea.

Symptoms usually occur two to ten days after being exposed.

How is Legionnaires’ Disease Treated?

Most cases respond well to antibiotics such as fluoroquinolones, azithromycin, or doxycycline. Mild cases can be treated in an outpatient setting but some people still require hospitalization.

After a two-week cycle with antibiotics, patients need to go through close follow-up screening to make sure that all the symptoms have disappeared and that the bacteria have been completely eliminated.

Last Reviewed:
September 21, 2016
Last Updated:
October 23, 2017
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