document: 20 July 2016 Last updated at 08:43 BST
  Better education, the availability of drugs that fight the spread of the virus and the prevention of HIV transmission to newborn babies have all played a role.
  But it is proving stubborn to get rid of.
  As South Africa hosts a major HIV-Aids conference, the BBC's Karen Allen has been to one of the country's HIV hot spots in KwaZulu-Natal.