1793 Philadelphia yellow fever epidemic the origin of the fever nor that it was transmitted by mosquitoes (which was not verified until the late nineteenth 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 the members, based on the mistaken assumption that native Africans would have the same partial immunity to the new disease as many had to malaria, the most common source of fever epidemics during the summer months. Black nurses aided the sick and the
1793 Philadelphia yellow fever epidemic vector of the 1793 plague in Philadelphia (and other Atlantic ports) was the British merchant ship "Hankey", which had fled the West African colony of Bolama (an island off West Africa, present day Guinea-Bissau) the previous November, trailing yellow fever at every port of call in the Caribbean and eastern Atlantic seaboard. See: "The Ship of Death: The Voyage That Changed the Atlantic World". After two weeks and an increasing number of fever cases, Dr. Benjamin Rush, a doctor's apprentice during the city's 1762 yellow fever epidemic, saw the pattern; he recognized that yellow fever had returned. Rush alerted his