Scientists tracking the Ebola outbreak
in Guinea say the virus has mutated.
Researchers at the Institut Pasteur in
France, which first identified the outbreak
last March, are investigating whether it
could have become more contagious.
More than 22,000 people have been
infected with Ebola and 8,795 have died in
Guinea, Sierra Leone and Liberia.
Scientists are starting to analyse hundreds
of blood samples from Ebola patients in
They are tracking how the virus is
changing and trying to establish whether
it’s able to jump more easily from person
“We know the virus is changing quite a
lot,” said human geneticist Dr Anavaj
“That’s important for diagnosing (new
cases) and for treatment. We need to
know how the virus (is changing) to keep
up with our enemy.”
It’s not unusual for viruses to change over
a period time. Ebola is an RNA virus – like
HIV and influenza – which have a high rate
of mutation. That makes the virus more
able to adapt and raises the potential for
it to become more contagious.
“We’ve now seen several cases that don’t
have any symptoms at all, asymptomatic
cases,” said Anavaj Sakuntabhai.
“These people may be the people who can
spread the virus better, but we still don’t
know that yet. A virus can change itself to
less deadly, but more contagious and
that’s something we are afraid of.”
But Professor Jonathan Ball, a virologist
at the University of Nottingham, says it’s
still unclear whether more people are
actually not showing symptoms in this
outbreak compared with previous ones.
“We know asymptomatic infections
occur… but whether we are seeing more
of it in the current outbreak is difficult to
ascertain,” he said.
“It could simply be a numbers game, that
the more infection there is out in the
wider population, then obviously the
more asymptomatic infections we are
going to see .
Another common concern is that while
the virus has more time and more “hosts”
to develop in, Ebola could mutate and
eventually become airborne.
There is no evidence to suggest that is
happening, however. The virus is still only
passed through direct contact with
infected people’s body fluids.
“At the moment, not enough has been
done in terms of the evolution of the virus
both geographically and in the human
body, so we have to learn more. But
something has shown that there are
mutations,” said Institut Pasteur virologist
“For the moment the way of transmission
is still the same. You just have to avoid
contact (with a sick person)”
“But as a scientist you can’t predict it
won’t change. Maybe it will.”
Researchers are using a method called
genetic sequencing to track changes in the
genetic make-up of the virus. So far they
have analysed around 20 blood samples
from Guinea. Another 600 samples are
being sent to the labs in the coming
A previous similar study in Sierra Leone
showed the Ebola virus mutated
considerably in the first 24 days of the
outbreak, according to the World Health
It said: “This certainly does raise a lot of
scientific questions about transmissibility,
response to vaccines and drugs, use of
“However, many gene mutations may not
have any impact on how the virus
responds to drugs or behaves in human
The research in Paris will also help give
scientists a clearer insight into why some
people survive Ebola, and others don’t.
The survival rate of the current outbreak
is around 40%.
It’s hoped this will help scientists
developing vaccines to protect people
against the virus.
Researchers at the Institut Pasteur are
currently developing two vaccines which
they hope will be in human trials by the
end of the year.
One is a modification of the widely used
measles vaccine, where people are given
a weakened and harmless form of the
virus which in turn triggers an immune
response. That response fights and
defeats the disease if someone comes
into contact with it.
The idea, if it proves successful, would be
that the vaccine would protect against
both measles and Ebola.
“We’ve seen now this is a threat that can
be quite large and can extend on a global
scale,” said Professor James Di Santo, and
immunologist at the Institut.
“We’ve learned this virus is not a problem
of Africa, it’s a problem for everyone.”
He added: “This particular outbreak may
wane and go away, but we’re going to
have another infectious outbreak at some
point, because the places where the virus
hides in nature, for example in small
animals, is still a threat for humans in the
The best type of response we can think
of is to have vaccination of global