A group of scientists believe the origin of the HIV virus can be traced to the 1920s in a town named Kinshasa in present-day Democratic Republic of Congo, according to a study.
"Until now, most studies have taken a piecemeal approach to HIV's genetic history, looking at particular HIV genomes in particular locations," lead author Oliver Pybus of Oxford University said in a statement published by Oxford University. "For the first time, we have analyzed all the available evidence using the latest phylogeographic techniques, which enable us to statistically estimate where a virus comes from. This means we can say with a high degree of certainty where and when the HIV pandemic originated."
The study, which was originally published in 2014 but gained renewed interest of late, explains that in the early 20th century, Kinshasa was a boom town that was connected by railroad to a number of well-populated locations in Africa. And this advanced transportation infrastructure might be partially to blame for the virus spreading.
“Data from colonial archives tells us that by the end of 1940s over one million people were [traveling] through Kinshasa on the railways each year,” said Dr. Nuno Faria of Oxford University's Department of Zoology, the first author of the paper. “Our genetic data tells us that HIV very quickly spread across the Democratic Republic of the Congo (a country the size of Western Europe), [traveling] with people along railways and waterways to reach Mbuji-Mayi and Lubumbashi in the extreme South and Kisangani in the far North by the end of the 1930s and early 1950s. This helped establishing early secondary foci of HIV-1 transmission in regions that were well connected to southern and eastern African countries. We think it is likely that the social changes around the independence in 1960 saw the virus 'break out' from small groups of infected people to infect the wider population and eventually the world."
And because Kinshasa was a boom town, it also had a very active sex trade, according to Smithsonian Magazine. The sex trade, combined with the railroad network, caused HIV to spread in Africa, and later other regions.
The type of HIV virus that has led to a pandemic among humans likely originated from chimpanzees and spread to humans through the blood by the handling of bushmeat.