The exact origin of the virus in humans is unclear. Scientists surmise that it jumped from an animal population. In 1999 an international team of genetic scientists reported that HIV-1 can be traced to a closely related strain of virus, called simian immunodeficiency virus (SIV), that infects a subspecies of chimpanzee (Pan troglodytes troglodytes) in Western central Africa .Chimpanzees are hunted for meat in this region, and it is believed the virus may have passed from the blood of chimpanzees into humans through superficial wounds, probably in the early 1930's. Other scientists believe that the virus may have come from an African monkey or chimpanzees, to humans by a bite or eating.
