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
Community-acquired pneumonia monocytogenes" and a variety of mycobacteria. CAP-causing viruses may also be transferred from mother to child; herpes simplex virus (the most common) is life-threatening, and adenoviridae, mumps and enterovirus can also cause pneumonia. Another cause of CAP in this group is "Chlamydia trachomatis", acquired at birth but not causing pneumonia until two to four weeks later; it usually presents with no fever and a characteristic, staccato cough. CAP in older infants reflects increased exposure to microorganisms, with common bacterial causes including "Streptococcus pneumoniae", "Escherichia coli", "Klebsiella pneumoniae", "Moraxella catarrhalis" and "Staphylococcus aureus". Maternally-derived syphilis is also a cause of CAP