1976 Philadelphia Legionnaires' disease outbreak 1976 Philadelphia Legionnaires' disease outbreak The 1976 Legionnaires disease outbreak, occurring in the late summer in Philadelphia, Pennsylvania, was the first occasion in which a cluster of a particular type of pneumonia cases were determined to be caused by the "Legionella pneumophila" bacteria. Previous outbreaks were retroactively diagnosed as being most probably caused by Legionella bacteria. On July 21, 1976, the American Legion opened its annual three-day convention at the Bellevue-Stratford Hotel in Philadelphia, Pennsylvania. More than 2,000 Legionnaires, mostly men, attended the convention. The date and city were chosen to coincide with America’s celebration of the 200th anniversary of
1976 Philadelphia Legionnaires' disease outbreak the signing of the US Declaration of Independence at Philadelphia in 1776. On July 27, three days after the convention ended, Legionnaire Ray Brennan, a 61-year-old retired US Air Force captain and an American Legion bookkeeper, died at his home of an apparent heart attack. Brennan had returned home from the convention on the evening of July 24 complaining of feeling tired. On July 30, another Legionnaire, Frank Aveni, aged 60, also died of an apparent heart attack, as did three other Legionnaires. All of them had been convention attendees. Twenty-four hours later, on August 1, six more Legionnaires died.