Under the direction of the Influenza Commission of the Board for the Investigation and Control of Influenza and other Epidemic Diseases in the United States Army, observation posts have been set up in various parts of the country for early detection of influenza in Army personnel.
In the Virus Laboratory of the University of Michigan School of Public Health, such observations have been carried out for more than a year. On May 28, 1943 in the course of one of many routine surveys, several patients ill with influenza were seen at the Station Hospital, Fort Custer, Michigan. A strain of influenza virus, type A (Weiss), was isolated from the throat washings of 1 of these men, and in 2 other cases positive serologic evidence of type A infection was obtained. Since no epidemic prevalence of influenza or other respiratory disease was noted at that time and the usual seasonal decline
Salk JE, Menke WJ, Francis T. IDENTIFICATION OF INFLUENZA VIRUS TYPE A IN CURRENT OUTBREAK OF RESPIRATORY DISEASE. JAMA. 1944;124(2):93. doi:10.1001/jama.1944.62850020001007