Invasive Asian mosquito species threatens African cities: study Invasive Asian mosquito species threatens African cities: study WASHINGTON, Sept 16: A species of mosquito
originally from Asia threatens to put tens
of millions of city-dwellers in Africa at
higher risk of catching malaria as the
invading insect spreads throughout the
continent, a study said Monday.
Malaria — which killed 400,000 people in
2018, mainly children in Africa — is
caused by parasites that roughly 40
mosquito species spread among humans when
they feed.
The Anopheles gambiae group of mosquito
species are the main drivers of malaria’s
spread in Africa, but these insects
dislike the polluted puddles seen in
cities and haven’t learned to lay their
larvae in urban fresh water tanks.
For these reasons, most malaria
transmission in Africa occurs in rural
areas, reports AFP.
In a new study published in the
Proceedings on the National Academy of
Sciences (PNAS), medical entomologist
Marianne Sinka, of the University of
Oxford, charted the spread of another
species, Anopheles stephensi, which
originated in Asia.
This species has learned to slip through
cracks to access water tanks, favoring
those made from brick and cement.
“It’s the only one that’s really good at
getting into central urban areas,” Sinka
told AFP. Anopheles stephensi caused a
major outbreak in Djibouti City in the
Horn of Africa in 2012, a city where
malaria hardly existed, and has since been
observed in Ethiopia, Sudan and elsewhere.
Sinka and colleagues combined location
data for the species with spatial models
that identified the environmental
conditions characterizing its preferred
habitat: high-density urban areas where it
is hot and rainfall is plentiful.
Their study found that 44 cities are
“highly suitable” locations for the
insect, putting 126 million more Africans
— mainly around the equatorial regions —
at risk of malaria, compared to today.
“That means that Africa, which has already
got the highest burden of malaria, could
have an even bigger impact,” said Sinka,
with 40 percent of the continent’s
population in urban areas.
Unlike African mosquitoes, which like to
bite humans when at night when it is cool,
Anopheles stephensi can feed in the
evening when it is warmer, making bed nets
less effective.
So installing mosquito nets on windows,
soaking the walls in insecticides, and
covering the body are better ways to
protect against this species.
Longer term, the most effective measure is
to target the larvae: eliminate stagnant
water and tightly seal water tanks from
intrusion. These methods proved effective
in India, said Sinka.
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