Scientists have finally confirmed the origin of HIV: a chimpanzee virus called the SIVcpz, isolated from wild chimps in southern Cameroon, Africa.
It is thought that people hunting chimpanzees first contracted the virus - and that cases were first seen in Kinshasa, in the Democratic Republic of Congo - the nearest urban area - in 1930. ...
But SIVcpz has not been found to cause any Aids-like illnesses in chimpanzees, so researchers are investigating why the animals do not suffer any symptoms, when humans - who are so genetically similar - do.