Legionnaires' disease
noun
Le·gion·naires' disease
ˌlē-jə-ˈnerz- 
variants
or less commonly Legionnaire's disease
: pneumonia that is caused by a bacterium (Legionella pneumophila), is characterized initially by symptoms resembling influenza (as malaise, headache, and muscular aches) followed by high fever, cough, diarrhea, severe pneumonia, and mental confusion, and that may be fatal especially in elderly and immunocompromised individuals
Examples of Legionnaires' disease in a Sentence
Recent Examples on the Web
People infected with the bacterium Legionella pneumophila may develop Legionnaires' disease, a type of pneumonia.
—
Noe Padilla, USA Today, 7 May 2026
The sheriff's administration building has had filters since December after officials learned that a custodial employee assigned to the building was hospitalized with Legionnaires' disease in November.
—Christina Hall, Freep.com, 5 Mar. 2026
According to the Oakland County Health Department, the tests were ordered after a custodial employee was diagnosed with Legionnaires' disease.
—Nick Lentz, CBS News, 17 Jan. 2026
Six cases of Legionnaires' disease have been reported at Christ Hospital since October, and three of those people died.
—Randy Tucker, Cincinnati Enquirer, 23 Dec. 2025
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Noe Padilla, USA Today, 7 May 2026
The sheriff's administration building has had filters since December after officials learned that a custodial employee assigned to the building was hospitalized with Legionnaires' disease in November.
—Christina Hall, Freep.com, 5 Mar. 2026
According to the Oakland County Health Department, the tests were ordered after a custodial employee was diagnosed with Legionnaires' disease.
—Nick Lentz, CBS News, 17 Jan. 2026
Six cases of Legionnaires' disease have been reported at Christ Hospital since October, and three of those people died.
—Randy Tucker, Cincinnati Enquirer, 23 Dec. 2025
Cite this Entry
“Legionnaires' disease.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/Legionnaires%27%20disease. Accessed 12 May. 2026.
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