Legionnaires' disease that occur globally is not known. Legionnaires' disease is the cause of an estimated 2-9% of pneumonia cases that are acquired outside of hospital. An estimated 8,000 to 18,000 cases a year in the United States require hospitalization. Outbreaks of disease account for a minority of cases. While it can occur any time of the year, it is more common in the summer and fall. The disease is named after the outbreak where it was first identified, at a 1976 American Legion convention in Philadelphia. The length of time between exposure to the bacteria and the appearance of symptoms is
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