Aids ‘family tree’ traced back to Kinshasa

New research has traced the origin of the Aids pandemic back to 1920s Kinshasha, where a “perfect storm” of rapid population growth, a roaring sex trade, and good railway transport facilitated the spread of the HIV virus.

Scientists, whose work was published in Science, used archived samples of HIV’s genetic code to trace its source. Teams from the Universities of Oxford and Leuven, in Belgium, analysed mutations in the code to construct a ‘family tree’ for the virus.

Public health campaigns which used unsterilised needles for injections may have helped spread the virus from Kinshasa, in what is now the Democratic Republic of Congo, to neighbouring regions. The Belgian-backed railways, which carried a million people through the city each year, are also likely to have contributed to the disease’s spread. HIV probably crossed the Atlantic in Haitian teachers returning home. By the time the situation had improved in Kinshasa a few decades later, the virus was already starting to spread around the world.

HIV arose from a mutation of the simian immunodeficiency virus, which is carried by chimpanzees. It probably made the species jump to humans through contact with infected blood while handling bush meat. The virus has mutated on several occasions: one such event led to the HIV-1 subgroup, which affects tens of thousands in Cameroon. Yet only one such cross-species jump, HIV-1 subgroup M, went on to affect millions around the world.

The researchers suggest that the spread of the M-group viruses had more to do with the conditions being right in Kinshasa at the time than because the viruses were better adapted for transmission and growth in humans. HIV subsequently went on to infect nearly 75 million people across the globe.

This year, a report by the United Nations Aids agency suggested that the Aids epidemic could be brought under control by 2030. But while the overall number of new HIV infections and deaths from Aids are falling, access to antiretroviral drugs remains an issue in places like Nigeria, where 80 per cent of people don’t have access to treatment.

Around 35 million people are still living with HIV, and three quarters of new cases present in just 15 countries. Charity Medecins Sans Frontieres has warned that most of those in need of HIV drugs still have no access to them.

Aids-related deaths have fallen by 20 per cent over the past three years, to 1.5 million a year. And the 2.1 million new cases in 2013 represents a 38 per cent decline since 2001. Increased access to drugs has improved the situation. Also, the number of men getting circumcised to reduce their risk of contracting HIV has doubled.