An international team of scientists has reconstructed the genetic history of the HIV-1 group M pandemic, the event that saw HIV spread across the African continent and around the world, and concluded that it originated in Kinshasa, the capital of what’s now the Democratic Republic of Congo.
The team’s analysis suggests between the 1920s and 1950s, a “perfect storm” of population growth, sex and railway links allowed HIV to spread from Kishasa across the globe.
HIV is known to have been transmitted from primates and apes to humans at least 13 times but only one of these transmission events has led to a human pandemic. It was only with the event that led to HIV-1 group M that a pandemic occurred, resulting in almost 75 million infections to date.
A report of the research is published in Science.
Professor Oliver Pybus of Oxford University’s Department of Zoology is a senior author of the paper. He said:
For the first time we have analysed 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.
It seems a combination of factors in Kinshasa in the early 20th Century created a “perfect storm” for the emergence of HIV, leading to a generalised epidemic with unstoppable momentum that unrolled across sub-Saharan Africa.
One of the factors the team’s analysis suggests was key to the HIV pandemic’s origins was the DRC’s transport links, in particular its railways, that made Kinshasa one of the best connected of all central African cities.
Dr. Nuno Faria of Oxford University’s Department of Zoology is first author of the paper. He said:
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. 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 … 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.
The researchers believe that following the original animal to human transmission of the virus (probably through the hunting or handling of bush meat) there was only a small ‘window’ during the Belgian colonial era for this particular strain of HIV to emerge and spread into a pandemic. By the 1960s, the railways that enabled the virus to spread vast distances were less active, but by that time the seeds of the pandemic were already sown across Africa and beyond.