discovery | The deadly virus responsible for the global HIV/AIDS pandemic emerged
around 1920 in the city of Kinshasa, the capital of the Democratic
Republic of the Congo, according to new research that has relevance to
the effort to understand how another deadly virus, Ebola, reestablished
itself in West Africa.
The study, published in the journal Science, reveals that the
HIV virus was already established and spreading in Africa long before
the U.S. Centers for Disease Control and Prevention first took note of
it. The CDC's first record of the illness occurred on June 5, 1981, when
an unusual type of "pneumonia" was detected in five homosexual men from
Los Angeles.
No one then knew that the deadly strain of the virus, which has
since killed an estimated 39 million people, had already taken hold in
the Congo some 60 years earlier.
"It seems a combination of factors in Kinshasa in the early
20th century created a 'perfect storm' for the emergence of HIV, leading
to a generalized epidemic with unstoppable momentum that unrolled
across sub-Saharan Africa," co-author Oliver Pybus, an Oxford University
zoologist, said.
Lead author Nuno Faria, also from Oxford University's
Department of Zoology, explained that "by the end of the 1940's, over
one million people were traveling through Kinshasa on the railways each
year." At the time, what is now the Democratic Republic of the Congo was
under Belgian colonial rule and experiencing steady urban growth
Faria and his team examined the genetics of 348 "HIV-1 group M"
samples from the former Belgian Congo, and 466 additional samples from
nearby regions. This particular viral strain, "M," has proven to be the
deadliest in humans, but virologist Beatrice Hahn of the University of
Pennsylvania explained to Discovery News that it represents just one of
several different instances where the illness jumped from a non-human
primate to people -- likely by the consumption or handling of bushmeat.
The researchers next compared the relatedness of the HIV
genetic sequences to create phylogenies, or family trees. The scientists
then calculated the rate at which the virus mutates to date the origin
of each "branch" on the trees.
This reconstruction of the genetic history of HIV-1 group M
revealed both the date and location of the epidemic's origins, placing
Kinshasa at ground zero.
Prior research suggests that one or more people first contracted the virus from an infected chimpanzee in southeastern Ca
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