Actualité scientifique
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N° 465
October(BC@J
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The geographic origin of AIDS
is now known
The AIDS epidemic has spread with the development of transport, including rail, as here in the Republic of Congo in 1967. (© IRD / A. Dessier)
A study published in Science !"#"$%&'( )'*'"+,( -.)( /0'( 1),/( /%!'( 20')'3( 20'&(
and how the world’s AIDS pandemic originated. Thanks to a statistical analysis
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in Kinshasa, the capital of what is now the Democratic Republic of the Congo. By
comparing this result with historical data, researchers explain how, from a single
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Good to know
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infecting great apes in South Cameroon. The pathogen was transmitted to humans by their closest cousin the chimpanzee.
It is thought to have crossed the species barrier during hunting parties (a bite from an infected monkey or a scratch during
cutting up, etc.) or from the consumption of bush meat.
Glossary
Genome sequencing: consists in determining the order of nucleotides in the DNA that constitutes genes.
Phylogeography: statistical study of the processes that govern the distribution of genealogical lines within a species.
CONTACTS
Epicentre of the disease discovered
in Kinshasa
Thanks to genome sequencing of the virus
and the latest phylogeographic techniques,
researchers have recreated the epidemic’s
genetic history. Scientists had previously
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Cameroon as the source of AIDS. There
have been several human contaminations
by these great apes throughout history, but
only one of these cases led to the spread of
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To determine where and when the epidemic
originated, researchers compared the
genetic diversity of the viruses collected in
the countries of the Congo Basin, considered
potential birthplaces. The result: the origin of
the scourge was Kinshasa, the capital of
what is now the Democratic Republic of the
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Emergence of a pandemic
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determined, scientists were able to link
their genetic data on the virus’ evolution
with historical data, to determine the
circumstances that enabled its outbreak
in Kinshasa and its spread among human
populations. Belgian colonial archives on
the former Zaire reveal that at the beginning
of the century a great deal of trade took
place by river (ivory, rubber, etc.) between
South-East Cameroon and Kinshasa. This
could explain why the human epidemic
broke out in the Congolese capital and not
in Cameroon where the chimpanzees that
contaminated humans are found.
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and the development of transport,
particularly railways, made Kinshasa one of
the most connected cities in Central Africa.
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people passed through the city each year
to reach the north or south of the country
or travel to neighbouring countries. This
unusual cocktail of factors, combined with
the virus’ genetic adaptability, led to its very
rapid spread throughout the country (large
like West Europe) as well as secondary
outbreaks as far as South and East
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changes, such as the rise in prostitution
and the use of non-sterile needles in public
health initiatives, undoubtedly contributed
to transforming small outbreaks of infection
into a real pandemic.
Coordination
Gaëlle Courcoux
Information and Culture
Department
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N"OK(LMM(9C=J(A@(AA(AB(BP
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www.ird.fr/la-mediatheque
Media Contact
Cristelle DUOS
Partners
Universities of Oxford, Louvain, Edinburgh,
California, Southampton, Lisbon, Sherbrooke
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References
N. FARIA, A. RAMBAUT, M. SUCHARD, G. BAELE,T.
BEDFORD, M. WARD, A. TATEM, J. D. SOUSA, N.
ARINAMINPATHY, J. PÉPIN, D. POSADA, MARTINE PEETERS,
O. PYBUS, P. LEMEY. The early spread and epidemic
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BC@J3(<.+E(MJW(&.E(WBCS(DDE(SW[W@E
YU;K(@CE@@BW\,4%'&4'E@BSWRMA((
KEELE ET AL. Chimpanzee reservoirs of pandemic and
&.&D"&5'!%4(:;<[@E(Science3(BCCW3(M@M(9SRPW=3(DE(
SBM[SBWE(;GGZ(CCMW[PCRS(-5%KC@CCMSRBS
Indigo, IRD Photo Library
Daina Rechner
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Contact
Martine Peeters, IRD researcher
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Photos : www.indigo.ird.fr
UMI Recherches translationnelles sur le VIH et
les maladies infectieuses - TransVIHMI (IRD / univ
Montpellier 1 / univ Cheikh Anta Diop de Dakar /
univ Yaoundé 1)
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© IRD/DIC, Juillet 2014 - Conception et réalisation graphique : L. CORSINI
AIDS is one of the most devastating
diseases in the history of humanity. Since
its transmission to humans by great apes,
the pathogen responsible, the human
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the discovery of its existence, little was known
about the chain of events at the origin of the
global pandemic. An international team, led
by the universities of Oxford and Louvain in
collaboration with IRD researchers, has just
published a new study in Science magazine
that reveals where the pandemic broke out
and how it spread.