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
Pneumocystis pneumonia The older species name "Pneumocystis carinii" (which now applies only to the "Pneumocystis" species that is found in rats) is still in common usage. As a result, "Pneumocystis" pneumonia (PCP) is also known as Pneumocystis jiroveci[i]" pneumonia and (incorrectly) as Pneumocystis carinii" pneumonia. Regarding nomenclature, when the name of "Pneumocystis" pneumonia (PCP) changed from "P. carinii" pneumonia to "P. jirovecii" pneumonia, it was at first asked whether "PJP" should replace "PCP". However, because the short name "PCP" was already well established among physicians that managed patients with "Pneumocystis" infection, it was widely accepted that that name could continue to be