Scientists figure out the city where AIDS originated


Photograph taken in Mbanza-Ngungu, Democratic Republic of Congo.
Carl Gierstorfer

Scientists know that the AIDS virus spread from chimpanzees to humans – but since the discovery of the virus in the 1960s, they have debated where on the African continent this happened.

A new study suggests that the HIV-1 group M – which is the viral subgroup that went pandemic – originated in Kinshasa, now the capital of the Democratic Republic of Congo (DRC), in the early 1920s.

The team of researchers came to this conclusion after analysing HIV-1 group M sequences from a major HIV sequence database, then merged these findings with geographic data and known patterns of the way the disease spreads.

The combined data suggested that the viral subgroup M gradually spread throughout modern-day DRC up until 1960. This was likely due to Kinshasa’s thriving commercial activity, as the city was a hub for transportation networks on both railways and waterways for the ivory and bush meat trades. These networks connected the city’s urban regions with the outer rural areas.

But after 1960, the infection rate tripled and subgroup M went pandemic, spreading rapidly across the continent. The data also suggested that there were several factors behind this new phase of the virus’s spread. African cities were drawing large numbers of male labourers to work for the ports and rail networks. In turn, there was an increase in sexual promiscuity and commercial sex work that led to the rapid spread of the HIV-1 group M virus.

The researchers say their results are also consistent with the theory doctors unwittingly played a key role in HIV’s pandemic spread, via the unsterilized injections routinely given to sex workers at health clinics.

The study could help us better understand how to prevent the spread of other diseases carried by blood-borne pathogens, such as hepatitis C.

This figure from the original article details the spatial dynamics of HIV-1 group M spread. Circles represent sampled locations and are colored according to the estimated time of introduction of HIV-1 group M from Kinshasa. As indicated in the figure key, the gradient colours depict the time scale of spatial movements.
Faria et al

  1. http://www.sciencemag.org/lookup/doi/10.1126/science.1256739
  2. http://www.ncbi.nlm.nih.gov/pubmed/22328643
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