An international team of scientists investigating African human tissue samples preserved for nearly 50 years have suggested that the HIV/AIDS pandemic started around 100 years ago, between 1884 and 1924, at the same time as urbanization started growing in west central Africa.

The study was published in Nature by Michael Worobey from the University and colleagues from research centres around the world, including Democratic Republic of Congo.

Worobey and colleagues suggested that the growing urbanization of colonial Africa around the dawn of the 20th century, characterized by the growth of cities and a rise in high risk behaviours, set the stage for the HIV/AIDS pandemic and created the conditions that allowed the most pervasive strain of HIV, the HIV-1 group M, to spread among humans. This is at least 30 years before previous estimates of when HIV started to spread.

For the study, Worobey and colleagues spent 8 years screening large quantities of tissue samples until they discovered a genetic sequence of HIV-1 group M. Dating from 1960, this is the second oldest ever found. It came from a lymph-node tissue biopsy from a woman who lived in present day Kinshasa in the Democratic Republic of the Congo.

The oldest genetic fragment of HIV-1 group M came from a 1959 blood sample from another Kinshasa resident, this time a man.

They then compared the same genetic region in the 1959 virus to the 1960 virus and found more evidence that their common ancestor existed around 1900; it took more than 40 years for the genetic divergence between them to evolve, said the researchers. Previous research has shown that HIV started in chimps and spread to humans in southeastern Cameroon.

[2 Oct 2008 13:23]

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