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
Colorado tick fever Colorado tick fever Colorado tick fever (CTF) (also called mountain tick fever, American tick fever, and American mountain tick fever) is a viral infection (Coltivirus) transmitted from the bite of an infected Rocky Mountain wood tick ("Dermacentor andersoni"). It should not be confused with the bacterial tick-borne infection, Rocky Mountain spotted fever. The type species of the genus "Coltivirus", Colorado tick fever virus (CTFV) infects haemopoietic cells, particularly erythrocytes, which explains how the virus is transmitted by ticks and also accounts for the incidence of transmission by blood transfusion. The disease develops from March to September, with the highest infections