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
Classification of pneumonia Classification of pneumonia Pneumonia can be classified in several ways, most commonly by where it was acquired (hospital versus community), but may also by the area of lung affected or by the causative organism. There is also a combined clinical classification, which combines factors such as age, risk factors for certain microorganisms, the presence of underlying lung disease or systemic disease, and whether the person has recently been hospitalized. Community-acquired pneumonia (CAP) is infectious pneumonia in a person who has not recently been hospitalized. CAP is the most common type of pneumonia. The most common causes of CAP vary depending