[afro-nets] Charting Path of Deadly Ebola Virus

[Leela McCullough <leela@healthnet.org>]

Charting the Path of the Deadly Ebola Virus in Central Africa
-------------------------------------------------------------
PLoS Biol 28 Oct 2005
http://dx.doi.org/10.1371/journal.pbio.0030371

Over the past ten years, separate outbreaks of the deadly Zaire
strain of Ebola virus (ZEBOV) have killed hundreds of humans and
tens of thousands of great apes in Gabon and the Republic of
Congo-which harbor roughly 80% of the last remaining wild go-
rilla and chimpanzee populations. In a new study, Peter Walsh,
Roman Biek, and Leslie Real combined genetic data with informa-
tion on the timing and location of past ZEBOV outbreaks to sup-
port the hypothesis that a consistently moving wave of ZEBOV in-
fection recently spread to outbreak sites in Gabon and Congo.

In the prevailing view, ZEBOV arose from long-persistent local
strains after increased contact between humans or great apes and
an unidentified reservoir host. But Walsh et al. found support
for the alternative hypothesis: that ZEBOV had recently spread
to the outbreak regions.

This is good news because a virus that spreads at a predictable
rate in a predictable direction is far easier to control than
one that emerges by chance or at the hands of an unknown trig-
ger. The authors modeled the virus's spread based on assumptions
of a long-persistent virus versus a recently emerged virus, and
tested the predictions of these competing hypotheses using ge-
netic data-gathered from gene sequences taken from human samples
at the different outbreak sites-and information on the spatio-
temporal dynamics of the outbreaks.

Though the strength of the individual lines of evidence is not
conclusive when considered separately, taken together, they sup-
port the view that ZEBOV is spreading as a wave from the first
epidemic in Yambuku, Gabon. Following its current course, ZEBOV
may hit populated areas east of Odzala National Park within 1-2
years and reach most parks containing large populations of west-
ern gorillas in 3-6 years.

Two Ebola outbreaks have already hit human populations west of
Odzala, and over the past two years, the largest gorilla and
chimp populations in the world, found in Odzala, have been dev-
astated-the disease is spreading to the last unaffected sector
of the park right now.

These findings suggest that strategies to protect villagers and
some of the last remaining wild apes from future outbreaks would
do best to concentrate efforts at the front of the advancing
wave-and start acting now.

Citation: Walsh PD, Biek R, Real LA (2005) Wave-like spread of
Ebola Zaire. PLoS Biol 3(11):
http://dx.doi.org/10.1371/journal.pbio.0030371

All works published in PLoS Biology are open access. Everything
is immediately available without cost to anyone, anywhere--to
read, download, redistribute, include in databases, and other-
wise use--subject only to the condition that the original au-
thorship and source are properly attributed. Copyright is re-
tained by the authors. The Public Library of Science uses the
Creative Commons Attribution License.


--
Leela McCullough, Ed.D.
Director of Information Services
SATELLIFE
30 California Street, Watertown, MA 02472, USA
Tel: +1-617-926-9400
Fax: +1-617-926-1212
mailto:leela@healthnet.org
http://www.healthnet.org