Legionnaires' disease on symptom onset dates from past outbreaks. In this way, the eventual likely size of an outbreak can be predicted, enabling efficient and effective use of public health resources in managing an outbreak. The first recognized cases of Legionnaires' disease occurred in 1976 in Philadelphia; among more than 2000 attendees of an American Legion convention held at the Bellevue-Stratford Hotel, 182 attendees contracted the disease and 29 of them died. In April 1985, 175 people in Stafford, England, were admitted to the District or Kingsmead Stafford Hospitals with chest infection or pneumonia. A total of 28 people died. Medical diagnosis
1976 Philadelphia Legionnaires' disease outbreak testing specimens. While the Center for Disease Control responded rapidly, as did the Pennsylvania Health Department, it took six months for the CDC microbiologist Joseph McDade to discover the cause of the outbreak. He initially thought the cause was viral because blood and tissues from the victims failed to grow bacteria when incubated in culture medium. His subsequent attempts to isolate the viral agent in eggs included antibiotics to kill off "contaminating" bacteria. It was only when he omitted the antibiotics that the bacteria grew in eggs. Attempts to reproduce the disease in mice, the standard laboratory animal model, also