HIV Pandemic Spread By The ‘Perfect Storm’

Chuck Bednar for redOrbit.com – Your Universe Online
The origin of the AIDS pandemic can be traced back to a city in what is now the Democratic Republic of Congo, an international team led by scientists from Oxford University and the University of Leuven report in the latest edition of the journal Science.
According to first author Dr. Nuno Faria of Oxford’s Department of Zoology and his colleagues, a reconstruction of the genetic history of the HIV-1 group M pandemic concluded the pathogen originated in the city of Kinshasa, and that the common ancestor of the group is highly likely to have emerged there sometime around 1920.
Furthermore, the researchers reported that while HIV is known to have been transmitted from apes and primates to people at least 13 times, only one of those strands, the HIV-1 group M, resulted in a human pandemic.  The team’s analysis concluded there was a 95 percent chance the HIV-1 group M transmission originated between 1909 and 1930.  The spread of the HIV-1 group M from virus to pandemic is attributed to a “perfect storm” of factors, including urban growth, the advanced railway and river transportation, and changes to the sex trade.
While it is quite likely the virus crossed from chimpanzees to humans in southern Cameroon several years before the current pandemic began, the pathogen which causes AIDS remained a regional infection until it reached Kinshasa, according to The Guardian. At the time, Kinshasa was the largest and fastest growing city in the region, and records show that by the 1940s, more than one million people had passed through the city on the railways alone.

Image Above: Kinshasa’s railways helped to make it on of Africa’s best connected cities. Credit: Atlas du Congo Belge et du Ruanda-Urundi, Gaston Derkinderen, Les Transport, Elsevier, Bruxelles, 1955
By 1960, the rate of new pandemic HIV infections outpaced the growth of the regional population, the researchers reported. While trains and other forms of transportation helped spread the disease, The Guardian notes that other factors were in play as well. The UK newspaper said that records suggest Kinshasa’s predominantly male population had a high demand for sex workers, and that doctors may have helped spread the virus by using unsterilized needles at sexual health clinics in the region.
“Our genetic data tells us that HIV very quickly spread across the Democratic Republic of the Congo, travelling with people along railways and waterways to reach Mbuji-Mayi and Lubumbashi in the extreme South and Kisangani in the far North by the end of the 1930s and early 1950s,” Dr. Faria explained in a statement Friday.
“This helped establishing early secondary foci of HIV-1 transmission in regions that were well connected to southern and eastern African countries,” he added. “We think it is likely that the social changes around the independence in 1960 saw the virus ‘break out’ from small groups of infected people to infect the wider population and eventually the world.”
Dr. Faria and experts from Belgium, Canada, France, Portugal, Spain, the UK and the US reconstructed the history of the HIV pandemic, which to date has infected nearly 75 million worldwide, using historical records and DNA samples of the virus dating back to the 1950s. The genetic material allowed them to construct a family tree that traced the ancestry of the AIDS-causing pathogen, and statistical models helped them delve back into its origins.
“You can see the footprints of history in today’s genomes, it has left a record, a mutation mark in the HIV genome that can’t be eradicated,” study co-author and Oxford professor Oliver Pybus told BBC News online health editor James Gallagher. It was those mutational marks which allowed Pybus, Dr. Faria and their colleagues to reconstruct HIV’s family trees, Gallagher added.
University of Nottingham professor Jonathan Ball told BBC’s Gallagher that the study was “a fascinating insight into the early phases of the HIV-1 pandemic. It’s the usual suspects that are most likely to have helped the virus get a foothold in humans – travel, population increases and human practices such as unsafe healthcare interventions and prostitution.” He added that the suggestion the spread “had more to do with the conditions being right” than with the disease adapting for growth and transmission in humans would “prompt interesting and lively debate.”
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