Did you know that the earliest known outbreak of Legionnaires’ disease in the United States occurred in Minnesota in 1957?

Between June 7 and August 9 of that year, 78 people in Austin – many who worked at the local Hormel meat-packing plant – were hospitalized with an acute respiratory disease, most suffering symptoms that included fever, headache, cough, and pneumonia. Two victims died.

The scientific breakthrough that helped identify the outbreak – and give the disease a name – occurred in December 1976 when Dr. Joseph McDade, a laboratory scientist for the Centers for Disease Control and Prevention (CDC), isolated the bacterium that caused the disease and identified it as Legionella pneumophila (L. pneumophila). McDade was trying to find the cause of an illness that sickened more than 200 and resulted in the deaths of 34 who attended the 1976 American Legion Bicentennial Convention at the Bellevue-Stratford Hotel in Philadelphia, PA. The following April, the CDC gave the mystery illness a name: Legionnaires’ disease.

It wouldn’t be determined that the Austin outbreak was Legionnaires’ disease until 1979, when a test of blood serum of 15 of the 1957 victims showed elevated levels of L. pneumophila in 12 cases. The blood work, combined with the clinical and epidemiologic observations of the outbreak, supported the assertion that Austin was the earliest U.S. occurrence of Legionnaires’ disease.

The identification of the L. pneumophila bacterium enabled CDC scientists to search for similar unsolved outbreaks. In addition to the Austin event in 1957, earlier outbreaks were determined to have occurred at a psychiatric hospital in Washington, DC, in 1965, and also at a convention of the Independent Order of Odd Fellows at the Bellevue-Stratford Hotel in 1974.