The spread of HIV can be traced back to about 80 chimpanzees in Africa that infected about three bush-meat hunters circa 1921, according to a new book titled The Origins of AIDS reviewed by The New York Times. Jacques Pépin, MD, an infectious disease specialist, is the author. Scientists have determined that the M group—one of HIV-1's four genetic groups, which accounts for 99 percent of all HIV cases—reached humans around 1921. Using data from that era, Pépin was able to make his calculations. He argues that since sex alone was not enough to spread the virus widely, there were several “amplifiers” along the way, including blood-borne routes such as unsterile equipment at immunization clinics and plasma centers.

To read the Times article, click here.