1793 Philadelphia yellow fever epidemic immune to the fever. Many of the slaves in Charleston in 1742 could have gained immunity before having been transported from Africa, by having been exposed to yellow fever in a mild case. People who survived one attack gained immunity. A total of 240 blacks died, in proportion to their population at the same rate as whites. Given the limited resources and knowledge of the times, the city's response was credible. The medical community did not know the natural history of yellow fever, a viral infection spread by the "Aedes aegypti" mosquito. Efforts to clean the city did not defeat
Yellow fever there were seriously affected by the "yellow jack". Wanting to regain control of the lucrative sugar trade in Saint-Domingue (Hispaniola), and with an eye on regaining France's New World empire, Napoleon sent an army under the command of his brother-in-law General Charles Leclerc to Saint-Domingue to seize control after a slave revolt. The historian J. R. McNeill asserts that yellow fever accounted for about 35,000 to 45,000 casualties of these forces during the fighting. Only one-third of the French troops survived for withdrawal and return to France. Napoleon gave up on the island and his plans for North America, selling