HEALTH: Malaria Sreading to New altitudes

By Rebecca Morelle
Science reporter, BBC World
Service

Malaria parasites - seen here
infecting red blood cells - and
mosquitoes do not like cold
temperatures
Warmer temperatures are
causing malaria to spread to
higher altitudes, a study
suggests.

Researchers have found that
people living in the highlands of
Africa and South America are at
an increased risk of catching the
mosquito-borne disease during
hotter years.
They believe that temperature
rises in the future could result in
millions of additional cases in
some areas.

The research is published in the
journal Science.
Prof Mercedes Pascual, from the
University of Michigan in the US,
who carried out the research,
said: "The impact in terms of
increasing the risk of exposure
to disease is very large."

Vulnerable to disease
Areas at higher altitudes have
traditionally provided a haven
from this devastating disease.
Both the malaria parasite and
the mosquito that carries it
struggle to cope with the cooler
air.

Prof Pascual said: "The risk of
the disease decreases with
altitude and this is why
historically people have settled in
these higher regions."
But the scientists say the disease
is entering new regions that had
previously been malaria-free.
To investigate, scientists looked
at densely populated areas in
the highlands of Colombia and
Ethiopia, where there are
detailed records of both
temperature and malaria cases
from the 1990s to 2005.

They found that in warmer
years, malaria shifted higher into
the mountains, while in cooler
years it was limited to lower
elevations.
"This expansion could in a sense
account for a substantial part of
the increase of cases we have
already observed in these areas,"
said Prof Pascual.

The highlands of Ethiopia could
be more vulnerable to malaria if
temperatures rise
The team believes that rising
temperatures could cause a
further spread.
In Ethiopia, where nearly half of
the population live at an altitude
of between 1,600m (5,250ft)
and 2,400m, the scientists
believe there could be many
more cases.

"We have estimated that, based
on the distribution of malaria
with altitude, a 1C rise in
temperature could lead to an
additional three million cases in
under-15-year-olds per year,"
said Prof Pascual.
The team believes that because
people living in areas that have
never been exposed to malaria
are particularly vulnerable to the
disease, attempts to stop the
spread should be focused on
areas at the edge of the spread.

The disease is easier to control
there than at lower altitudes
where it has already established.
According to the latest estimates
from the World Health
Organization, there were about
207 million cases of malaria in
2012 and an estimated 627,000
deaths. Most deaths occur
among children living in Africa.

Reference: BBC News