Cases of
Dengue Drop 91 Percent Due to Genetically Modified Mosquitoes
--Richard Levine
Once again, a technique that modifies
insects in order to control their populations has been proven effective. RIDL,
which stands for Release of Insects carrying a Dominant Lethal, has been
applied to diamondback moths, Mediterranean fruit flies, and olive flies, and it has been used in field trials on mosquitoes in order to reduce cases of dengue.
Scientists apply the RIDL technique to
male insects in the lab, which basically makes them die young unless they
receive a substance called tetracycline. As long as they have tetracycline,
they will live, but take it away from them and they’re goners. It’s almost as
if they’re breeding insects that are drug addicts from birth Next, they release
millions of these male insects into the wild and allow them to mate with
females. Since they no longer have tetracycline, the males die soon after
mating. Their offspring, which also need tetracycline to live, will die before
reaching adulthood since they have no access to the substance. Using this
technique, scientists have reduced the cases of dengue, which can be deadly, by
91% in a neighborhood called CECAP/Eldorado in the city Piracicaba, which is
located in the Brazilian state of São Paulo. There were only 12 cases of dengue
in the area, versus 133 cases the previous year. Surrounding areas also saw a
reduction of dengue cases by 52%.
This is good news not only for
potential victims of dengue, but also for people who may be susceptible to
Zika, chikungunya, and yellow fever because the mosquito that transmits dengue
— Aedes aegypti — also transmits these other diseases. The
Brazilian health authorities and Oxitec, the company that produces the
mosquitoes, call this undertaking the Friendly Aedes project. “Over the
course of one year, we were able to bring the dengue fever incidence down by
more than 50% in Piracicaba — the outcome of diligent work to eliminate still
water spots, the breeding site of the mosquito,” said the city’s Secretary of
Health, Pedro Mello. “In CECAP/Eldorado, where we had the Friendly™ Aedes
project, the reduction was extraordinary, going over 90%.” “We are delighted
with the result achieved so far by Friendly™ Aedes which shows the
potential of our approach,” said Glen Slade, Oxitec do Brasil director. “We
hope to see this effect on a larger scale beyond the limited area of
CECAP/Eldorado with our expansion into Piracicaba’s downtown city.” Friendly Aedes
mosquitoes have been used in Piracicaba since April 30, 2015, when the first
insects were released in CECAP/Eldorado. By January 2016, the technology had
already reduced the number of wild Aedes aegypti larvae by 82%
in the treated area, compared to a non-treated area.
This novel way of reducing the
mosquito population has the added benefit of reducing the use of chemical
insecticides. Scientists saw similar
reductions of dengue in previous trials in the Cayman Islands
in 2010 and in a suburb called Juazeiro, which is located in the state of Bahia
in Brazil.
By
Mr. S. Karthi
Assistant Professor
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