A new study, published in Science magazine, examined the genetic origins of Human Immunodeficiency Virus (HIV) in humans.  Using research techniques that combined statistical analysis with genetic sequencing, the study authors traced HIV back to 1920s Kinshasa, which is presently known as the Democratic Republic of Congo.  Spread and awareness of the virus after 1960 could be traced back to its presence in Kinshasa earlier in the twentieth century.

According to Time Magazine, HIV is a mutation of simian immunodeficiency virus, a virus found in chimpanzees, and the researchers think it probably entered the human species through infected blood from bush meat.  The spread of HIV among humans could be attributed to the booming expansion of the region’s population, a growing sex trade, and the use of unsterilized needles in healthcare settings.  Today, it is clear that HIV and other diseases can be spread through needle sharing and unprotected sex, these practices were not uncommon several decades ago.

An additional source of the spread could be attributed to the growth of transportation networks.  National Geographic reports that the modernization of Kinshasa and the Democratic Republic of Congo allowed the virus to spread beyond a concentrated region.  By the end of 1940, it is estimated that one million people were using the rails in Kinshasa.  Transport networks connecting other major cities to Kinshasa can account for the first cases of HIV in each of those cities.

Now, the virus has moved beyond Africa and can be seen all over the world.  The U.S. Centers for Disease Control and Prevention (CDC) estimates that, at the end of 2009, an estimated 1,148,200 people aged 13 and older were living with HIV infection in the U.S. In 2011, the estimated number of persons diagnosed with AIDS in the United States was 32,052. The cumulative estimated number of AIDS diagnoses through 2010 in the United States was 1,155,792.