MONTPELLIER, France - Behind air-tight doors in a lab in a
southern French city, scientists in protective coveralls wage war against a
fingernail-sized danger.
Lurking in net cages is their
foe: the Asian tiger mosquito, capable of spreading dengue fever and other
tropical diseases in temperate Europe.
First spotted in Albania in 1979,
the black-and-white striped invader has gained a foothold on Europe's
Mediterranean rim and is advancing north and west, according to captors'
reports.
Colonies are established in 20
European countries, in moderate climes as far north as Germany, Belgium and the
Netherlands.
"The risk of disease is very
low but it is growing," entomologist Jean-Baptiste Ferre told AFP at
France's leading mosquito-control institute.
"The more mosquitoes there
are, the higher the risk."
The Asian tiger mosquito - Latin
name Aedes albopictus - can spread many kinds of viruses.
They include dengue, which can
result in a deadly haemorrhagic fever, as well as West Nile virus, St. Louis
encephalitis and a painful disease of the joints called chikungunya.
A. albopictus transmits the virus
by taking blood from a sick person and handing on the pathogen the next time it
takes a meal.
The worry is that the insect will
spread disease in Europe by biting infected people arriving from tropical
countries where the viruses are endemic.
In 2007, the tiger mosquito
caused a home-grown outbreak in Italy of chikungunya, and in 2010, 10
locally-transmitted cases of dengue occurred in Croatia.
That same year, two cases of each
disease surfaced in southern France, prompting the alarm bells to ring loudly.
From Montpellier, Ferre and his
colleagues at the Entente Interdepartementale pour la Demoustication en
Mediterranee (EID) monitor the spread with some 1,500 traps dotted around
France, luring mosquitoes to lay their eggs.
These provide insights into how
A. albopictus is adapting to European life, with its varied habitats and cooler
climate.
Ferre points to maps that begin
in 2004, when a tiny red dot represented the first settling of albopictus in
France around Menton, near the Italian border.
Year by year, the dot grows into
red tentacles that probe north and west.
The insect has a flight range of
only about 200 metres, so it hitch-hikes a ride in cars, trucks and traded
goods.
With climate change,
"further expansion is probable," the journal Vector-Borne and
Zoonotic Diseases warned this year.
That assessment is supported by
scientists at Britain's University of Liverpool who point to warming trends in
the Balkans and northwestern Europe.
Asian tiger mosquitoes are
aggressive and robust, able to breed prolifically in their short, 10-day lives.
Feeding during the day, they can
bite several people in quick succession, and their offspring can hatch even
after long periods without water.
Worse, the insect is a stealthy
urban dweller.
It does not need large, open
bodies of water to reproduce, for it can lay its eggs in small, water-holding
receptacles such as flowerpots, toys and blocked gutters, and this makes it
much harder to fight.
Since May this year, surveillance
in France has thrown up 267 suspected dengue and chikungunya cases among people
who had arrived from abroad, said EID project coordinator Gregory Lambert.
AFP
No comments:
Post a Comment