By the time the AIDs virus, HIV, was discovered in 1983 it had been silently spreading in Africa for over 50 years. First it jumped from chimps to humans in south east Cameroon, most likely via a bush meat hunter. But scientists pinpoint Kinshasa (formerly Leopoldville, capital of the Belgian Congo) 700 kilometres away as the epicentre of the pandemic. So an unwitting human virus carrier probably took HIV down the Sangha and Congo Rivers by ferry, reaching the city by the 1920s. Then, aided by an explosion in STDs in the 1930s and possible virus transmission via antibiotic treatment using contaminated needles in the 1940s-1950s, the virus gained a foothold in Kinshasa. But there the trail went cold - exactly how HIV spread from Kinshasa to the rest of Africa remained a mystery.
Now scientists have found the answer – the railways. Built by colonial powers from the 1920s onwards to transport diamonds from remote mining towns to Leopoldville, trains inadvertently carried the virus inside human cargo to these rapidly growing centres. And from there HIV stealthy crept across Africa. Then in 1964 the virus took flight to Haiti and onwards to the US three years later – its global journey had begun.
- Dorothy H. Crawford, author of Virus Hunt
Image: Union of South Africa rail travel, by Andrew. CC-BY-2.0 via Flickr.