Scientists believe the first human who got HIV was a person in Africa in the early 1900’s. It infected only a small amount of people (disease not recognised), until it then turned into an epidemic reported to have started in New York (USA) in 1981. It then very quickly started spreading to other countries. This happened when Simian Immunodeficiency Virus (SIV) went from apes or chimpanzees to humans. This virus probably crossed to humans when a hunter came into contact with monkey blood while cutting up monkeys to eat. Research in October 2014 shows that the virus started in Kinshasa during the 1920s. It was quickly spread by unprotected sex, dirty needles used by intravenous drug users, and it then made its way into the medical blood supply . Some people described the spread of the disease as a "sexidemic" (widespread).