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
Rat-bite fever underarm. Symptoms generally appear within 2 to 10 days of exposure to the infected animal. It begins with the fever and progresses to the rash on the hands and feet within 2 to 4 days. Rash appears all over the body with this form, but rarely causes joint pain. Two types of Gram-negative, facultatively anaerobic bacteria can cause the infection. Rat-bite fever transmitted by the Gram-negative coiled rod "Spirillum minus" (also known as "Spirillum minor") is more rare, and is found most often in Asia. In Japan, the disease is called "sodoku". Symptoms do not manifest for two to four