How common is legionnaires' disease in the us?

3200 per year: There are somewhere in the range of 3200 cases reported each year -- but reported cases and actual cases are not necessarily the same number. Many consider this one of the top 3 causes of community acquire pneumonia.

Not rare: The annual rate is 180 to 360 cases per million population, or 56, 000 to 112, 000 cases per year in the usa. Only about 2% to 5% of us cases are currently reported to the cdc. Legionaires' disease causes 0.5% to 10% of all admitted pneumonia cases.