1793 Philadelphia yellow fever epidemic
During the 1793 Yellow Fever epidemic in Philadelphia, 5,000 or more people were listed in the official register of deaths between August 1 and November 9. The vast majority of them died of yellow fever, making the epidemic in the city of 50,000 people one of the most severe in United States history. By the end of September, 20,000 people had fled the city, including congressional and executive officials of the federal government. Most did not return until after the epidemic had abated in late November. The mortality rate peaked in October before frost finally killed the mosquitoes and brought an end to the outbreak. Doctors tried a variety of treatments but knew neither the origin of the fever nor that the disease was transmitted by mosquitoes (this information was not verified until the late 19th century). The mayor and a committee of two dozen organized a fever hospital at Bush Hill and other crisis measures. The assistance of the Free African Society was requested by the city and readily agreed to by its members. Parties mistakenly assumed that people of African descent would have the same partial immunity to the new disease as many had to malaria, which was