1976 Philadelphia Legionnaires' disease outbreak States Center for Disease Control and Prevention (CDC) in 2017 only use the term Legionnaires' disease to refer to the serious version with pneumonia. CDC investigators quickly discovered outbreaks of respiratory disease caused by "L. pneumophila" dating back to 1959. An outbreak of what was dubbed Pontiac fever occurred in a health department in Pontiac, Michigan in July 1967. No one died. Although caused by the same bacterium, Pontiac fever is a milder ailment than Legionnaires' disease. Pneumonia is absent in those with Pontiac fever. An outbreak of pneumonia in July–August, 1965, at St. Elizabeths Hospital in Washington, DC, which
Legionella cherrii were cultured around 36 °C in an environment containing 2.5% carbon dioxide. The genus "Legionella" is named after the 1976 pneumonia ("Legionella pneumophila") outbreak at the American Legion convention at the Bellevue-Stratford Hotel in Philadelphia. The genus was previously unknown, but it was established three years later. The specific term "cherrii" is derived from the scientist William B. Cherry due to his contributions on the studies of Legionellae. "L. cherrii" is rod-shaped and considered an oxidase-negative bacterium since it lacks cytochrome c oxidase and does not use oxygen in its electron transport chain. "L. cherrii" also has the ability to