The origin of the AIDS pandemic has been traced to the 1920s in the city of Kinshasa, in today's Democratic Republic of Congo. A feat of viral archeology was used to find its origins. It is a mutated version of a chimpanzee virus, which made the species-jump through contact with infected blood while handling bush meat. Roaring sex trade, population growth, unsterilized needles used in primitive clinics helped spread the virus thru the Congo. Railways had one million people flowing through the city each year, taking the virus to nearby regions, the same way as Ebola is today carried by plane from one continent to the other. HIV came to global attention in the 1980s and has infected nearly 75 million people.