query: When was the last case of smallpox in the US?
passage: Smallpox
Smallpox was an infectious disease caused by one of two virus variants, variola major and variola minor.[7] The last naturally occurring case was diagnosed in October 1977 and the World Health Organization (WHO) certified the global eradication of the disease in 1980.[10] The risk of death following contracting the disease was about 30%, with higher rates among babies.[6][11] Often those who survived had extensive scarring of their skin and some were left blind.[6]
passage: Eradication of infectious diseases
Smallpox (variola) occurred in two clinical varieties: "variola major", with a mortality rate of up to 40 percent, and "variola minor", also known as alastrim, with a mortality rate less than one percent. The last naturally occurring case of "Variola major" was diagnosed in October 1975 in Bangladesh. The last naturally occurring case of smallpox ("Variola minor") was diagnosed on 26 October 1977, on Ali Maow Maalin, in the Merca District, of Somalia. The source of this case was a known outbreak in the nearby district of Kurtuware. All 211 contacts were traced, revaccinated, and kept under surveillance.