Ebola: Is bushmeat behind the outbreak?

Bushmeat is believed to be the origin of the
current Ebola outbreak. The first victim's
family hunted bats, which carry the virus.
Could the practice of eating bushmeat, which is
popular across Africa, be responsible for the
current crisis?
The origin has been traced to a two-year-old
child from the village of Gueckedou in south-
eastern Guinea, an area where batmeat is
frequently hunted and eaten.
The infant, dubbed Child Zero, died on 6
December 2013. The child's family stated they
had hunted two species of bat which carry the
Ebola virus.
Bushmeat or wild animal meat covers any animal
that is killed for consumption, principally
chimpanzees, gorillas, fruit bats and monkeys. It
can even include porcupines, rats and snakes.
In some remote areas it is a necessary source of
food - in others it has become a delicacy.
In Africa's Congo Basin, people eat an estimated
five million tonnes of bushmeat per year,
according to the Centre of International
Forestry Research.
Ideal hosts
But some of these animals can harbour deadly
diseases. Bats carry a whole range of viruses and
studies have shown that some species of fruit
bats can harbour Ebola.
Via their droppings or fruit they have touched,
bats can then in turn infect other non-human
primates such as gorillas and chimpanzees. For
them, like us, this can be deadly. Bats on the
other hand can escape from it unscathed. This
makes them an ideal host for the virus.
Cooked or smoked bushmeat is not usually
harmful
Exactly how the virus "spills over" into humans
is still not clear, says Prof Jonathan Ball, a
virologist at the University of Nottingham.
There's often an intermediate species involved,
like primates such as chimpanzees, but evidence
shows people can get the virus directly from
bats, he told BBC Inside Science .
But it is difficult for the virus to jump the
species barrier from animals into humans, he
adds. The virus first has to "somehow gain
access to the cells in which it can replicate" by
contact with infected blood.
Most people buy bushmeat from markets once it
has already been cooked, so it is those hunting
or preparing the raw meat that are at highest
risk.
The current outbreak shows that, however
difficult or rare it is, infection is clearly possible
- though it must be remembered that each
further infection, from Child Zero to today, has
been caused by contact with an infected person.
Bitten and scratched
There has been talk of banning bushmeat, but
that may simply drive it underground, experts
have previously warned.
Hunting bushmeat is also a longstanding
tradition, explains Dr Marcus Rowcliffe from the
Zoological Society of London,
"It's a meat-eating society - there's a feeling
that if you do not have meat every day, you
haven't properly eaten. Although you can get
other forms of meat, there's traditionally very
little livestock production."
Many West Africans eat bushmeat
It is sold in markets across the region
More than 100,000 bats are thought to be
eaten in Ghana each year
In Ghana, for example, currently unaffected by
the outbreak, fruit bats are widely hunted. To
understand how people interact with this
particular type of bushmeat, researchers
surveyed nearly 600 Ghanaians about their
practices relating to bats.
The study found that hunters used several
different techniques to kill their prey including
shooting, netting, scavenging and catapulting.
All hunters reported handling live bats, which
often meant they came into contact with blood
and in some instances were bitten and
scratched.
'Healthy food'
These hunters are therefore the most at risk of
contracting viruses present in bats, explains one
of the authors, Dr Olivier Restif from the
University of Cambridge.
The work also uncovered that the scale of the
bat bushmeat trade in Ghana was much higher
than previously thought, with more than 100,000
bats killed and sold every year.
"People who eat bat bushmeat are rarely aware
of any potential risk associated with
consumption. They tend to see it as healthy
food," he told the BBC's Health Check
programme . This survey was carried out before
the current outbreak but the team says that
understanding the perceived risks could help
control future epidemics.
Fruit bats are believed to be a major carrier
of the Ebola virus but they do not show
symptoms
While there is a risk, this study exemplifies that
it is low. The estimate of more than 100,000
bats consumed has not resulted in a single case
of Ebola in Ghana.
Researchers have also monitored populations of
bats to test for Ebola and found very few animals
with detectable levels of the virus. Since the
first recorded outbreak in 1976 there have been
only 30 single spillover events from animals into
humans, according to new research which has
mapped all previous outbreaks.
But given Ebola's animal origin, it is perhaps
not surprising that bushmeat has been cited as
a core danger associated with the outbreak.
An opinion piece in the New Scientist said:
"The Ebola outbreak is an opportunity to clamp
down on a practice which both causes disease
outbreaks and empties forests of wildlife. At a
minimum, governments should zealously enforce
bans on the hunting and consumption of bats
and apes."
Bushmeat is often smoked before eaten or
sold at market
The Washington Post questioned "why West
Africans keep hunting and eating bushmeat
despite Ebola concerns".
Media coverage like this is not only unhelpful
but dangerous, warns Prof Melissa Leach, an
anthropologist at the University of Sussex.
"It's not a disease spread by eating bushmeat.
As far as we know it originated in one spillover
event from one bat to a child in Guinea.
"Subsequent to that it's been a human-to-
human disease. People are more vulnerable to
Ebola by interacting with people than by eating
bats."
She says negative coverage of bushmeat "has
deterred people from understanding the real
risk of infection".
However, despite the current outbreak, the very
fact that bats are carriers means there is always
a risk of further infection.
Dr Rowcliff says: "For any given contact the risk
is quite low but given the scale of contact it is
inevitable that there will be new emergences of
Ebola or potentially other diseases that the bats
harbour. The risks may be low but the
consequences are severe as we are seeing at the
moment."
This view is echoed by Dr Restif, who argues that
because the world's population is expanding,
close contract with wildlife will increase, which
is often "the first driver of these events".