Rajesh T. Gandhi, MD

Phylogeographic analyses suggest that the epidemic originated in Kinshasa in the 1920s and then spread to other regions of central Africa, perhaps along railway networks.

Previous work suggests that HIV-1 infection in humans began with cross-species transmission of simian immunodeficiency virus — a close relative — from chimpanzees in southern Cameroon. The earliest known infections with group M HIV-1, the cause of the current worldwide pandemic, occurred in Kinshasa in the Democratic Republic of the Congo (DRC). Now, investigators have analyzed HIV-1 sequences from archived samples collected in the DRC and neighboring countries and applied molecular clock techniques — estimates of the viral-mutation rate — to reconstruct how the virus spread.

The analysis suggests that group M HIV-1 emerged in Kinshasa around 1920, which is in line with previous work. From there, the virus spread to other population centers in central Africa, especially those that were connected to Kinshasa by railway networks. Around 1960, group M HIV-1 growth rates increased, and the virus spread, perhaps — the investigators speculate — because of contaminated injections or through commercial sex workers. Group M subtype B, which predominates in the U.S. and Europe, may have been carried out of Africa by Haitian professionals, who worked in the DRC (then called Republic of the Congo) in the 1960s. Subtype C, which accounts for ~50% of HIV-1 infections worldwide, appears to have developed in DRC mining regions and spread to other parts of Africa, probably through migrant labor.

Citation(s):

Faria NR et al. The early spread and epidemic ignition of HIV-1 in human populations. Science 2014 Oct 3; 346:56.