Ebola could hit 15 countries across Africa: Study of how disease has spread in past finds 22million people may be at risk of infection
- In a world first, Oxford scientists have created a new map of places most at risk of an Ebola outbreak
- Show, regions likely to be home to animals harbouring virus more widespread than previously feared,
- The virus is thought to be carried by
bats or other wild animals, particularly in West Africa
The Ebola outbreak could hit 15
countries across Africa - putting the lives of 22 million people at
risk, a groundbreaking study has found.
In a world first, Oxford scientists have created a new map of
places most at risk of an Ebola outbreak. They warn regions likely to be
home to animals harbouring the virus are more widespread than previously
feared, particularly in West Africa.
The virus, which can have a
human mortality rate of up to 90 per cent, is thought to be carried by
bats or other wild animals and to cross into humans through
contact with blood, meat or other infected fluids.
In a world first, Oxford scientists have created
a new map of places most at risk of an Ebola outbreak. They warn
regions likely to be home to animals harbouring the virus are more
widespread than previously feared, particularly in West Africa
These jumps by viruses
from animals to humans are known as 'zoonotic events' and were the cause
of major human disease outbreaks such as HIV and the H1N1 swine flu
pandemic.
The map, published
as the West Africa Ebola outbreak, the world's largest, stands at
almost 2,100, found that large swathes of central Africa as well as the
western part of the continent have traits of what the scientists called
'the zoonotic niche' for Ebola.
Understanding
better where people come into contact with Ebola-infected animals - for
example through hunting or eating bush meat - and how to stop them
contracting the deadly disease, is crucial to preventing future
outbreaks, the researchers said.
Nick Golding, an Oxford University
researcher who worked on the international mapping team, said it found
significantly more regions at risk from Ebola than previously feared.
'Up
until now there hadn't been a huge amount of research, but there was
one paper in which the at-risk area was much smaller,' he said in a
telephone interview. 'It didn't predict, for example, the area in Guinea
where this current outbreak first started.'
Previous
Ebola epidemics have been in central Africa, and a current outbreak in
Congo - separate from the one in West Africa - has infected around 30
people in recent weeks.
Liberia already accounts for about half of all
cases and deaths, and 'the number of new cases is increasing
exponentially,' the WHO warned
The virus, which can have a human mortality rate
of up to 90 percent, is thought to be carried by bats or other wild
animals and to cross into humans through contact with blood, meat or
other infected fluids
Health workers carry the body of a man, right,
suspected of dying from the Ebola virus and left in the street, in the
capital city of Monrovia, Liberia, last month. According to latest data
from the World Health Organisation (WHO), almost 2,100 have died from
Ebola in the current West Africa outbreak
According to latest data from
the World Health Organisation (WHO), almost 2,100 have died from Ebola
in the current West Africa outbreak, which has infected at least 4,000
people in Guinea, Sierra Leone, Liberia, Nigeria and Senegal. The WHO
says it will take months to bring the epidemic under control and is
warning there may be up to 20,000 cases before it is stopped.
Golding's
study, published in the journal eLife as a collaboration by scientists
at Oxford and University of Southampton in Britain, Canada's University
of Toronto, and HealthMap at Boston Children's Hospital in the United
States, did not seek to map potential human-to-human spread, but
focussed on where there is a risk of animals infecting people.
It used data from the current outbreak as well as previously unmapped infections in bats, primates and other animals.
Previous
studies have shown that the first patient in an Ebola outbreak is very
probably infected through contact with an infected animal. The so-called
"index case" in the current Congo outbreak was, according to the WHO, a
pregnant woman from Ikanamongo Village who butchered a bush animal that
had been killed and given to her by her husband.
How it all began: West Africa is being affected by cases of Ebola, centring on Sierra Leone and Liberia While the West Africa epidemic is vast, long-lasting and deadly, the scientists noted that this is almost entirely due to person-to-person spread, and said Ebola outbreaks are still relatively uncommon events.
'Although
the disease may be found in animals across a wide area, outbreaks are
still very rare; very few animals in this region have detectable
infections, and it is extremely rare for humans to catch the disease
from them,' said David Pigott, one of the lead authors of the study.
To
find areas most at risk, the team identified the predicted distribution
of bat species suspected of carrying the disease. They also mapped
environmental factors to find suitability for Ebola transmission from
host animals to people.
These
data were combined with detailed data on locations where humans have
been infected by wild animals and where infected animals have been
identified.
'This work was a first step towards understanding where outbreaks of the disease might occur in the future,' Golding said.
'To
prepare for future outbreaks and to deal with the current one we need
to understand how human movements cause the disease to spread once it
has entered the human population.'
As
a next step, the team wants to map the spread of the disease in past
and present outbreaks to identify the most likely direction for the
current outbreak and help target surveillance efforts, education and
medical interventions.
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