Posted on Reuters...
Bustling transport networks, migrant labor and changes to the sex trade in early 20th-century Congo created a “perfect storm” that gave rise to an HIV pandemic that has now infected 75 million people worldwide, researchers said on Thursday. In an analysis of the genetic history of the human immunodeficiency virus (HIV) that causes AIDS, the scientists said the global pandemic almost certainly began its global spread in the 1920s in Kinshasa in Democratic Republic of Congo (DRC).
Here, a confluence of factors including urban growth, extensive railway links during Belgian colonial rule and changes in sexual behavior combined to see HIV emerge in Congo’s capital and spread across the globe. Oliver Pybus, a professor at Oxford University’s zoology department who co-led the research, said that until now most studies have taken a piecemeal approach to HIV’s genetic history and looked only at certain HIV genomes in particular locations. “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,” he said. “This means we can say with a high degree of certainty where and when the HIV pandemic originated.”
United Nations AIDS agency (UNAIDS) data show that more than 35 million people worldwide are currently infected with HIV, and some 1.5 million people died of AIDS-related illness in 2013. Since the HIV/AIDS pandemic began, it has killed up to 40 million people worldwide. The disease is spread in blood, semen and breast milk. No cure exists, but AIDS can be kept at bay for many years in people with HIV who take cocktails of antiretroviral drugs.Various strains of HIV are known to have been transmitted from primates and apes to humans at least 13 times in history, but only one of those transmissions – of a strain known as HIV-1 Group M – led to the current human pandemic.
Pybus said the key questions centered on how this happened.”Why did most of (the HIV strains) die out, and why did some of them — like HIV-2 — go on to generate local epidemics in Africa, and why did only one go to become a global pandemic?” he said in a telephone interview. “To answer that, we needed to try to reconstruct the spread through space and time of the global pandemic strain.”
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