Index cases

infected houseworker in New York City

initial patient in the population of an epidemiological investigation

Canadian flight attendant, long misidentified as the index case of the North American AIDS Crisis (1953–1984)

Norwegian sailor and trucker, the earliest confirmed case of HIV/AIDS in Europe (1946-1976)

American teenager who died in 1969, thought to be the first death from AIDS in North America

medical patient

Meliandou is a village in Guéckédou Prefecture, in the Nzérékoré Region of southern Guinea. Medical researchers believe that the village was the location of the first known case of Ebola virus disease in the epidemic in West Africa. The patient zero of Ebola was a two-year-old boy who died in 2013. The boy's pregnant mother, sister, and grandmother also became ill with symptoms consistent with Ebola infection and died. People infected by those victims later spread the disease to other villages.