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 Small-scale trials of the technique, which involves infecting
mosquitoes with Wolbachia to prevent them from spreading the
viruses, have shown a significant reduction in their ability to
transmit Zika and dengue, prompting donors to back scale-up plans.
"The use of Wolbachia is a potential ground-breaking sustainable
solution to reduce the impact of these outbreaks around the globe
and particularly on the world’s poorest people," said Britain's
international development secretary Priti Patel as the larger
project was announced in London.
The control campaigns, scheduled to begin early next year in
Colombia's Antioquia and Brazil's Rio de Janeiro, will be funded
with $18 million from the British and United States governments, the
Wellcome Trust global health charity and the Bill & Melinda Gates
Foundation.
Zika has been linked to the birth defect microcephaly, characterized
by an abnormally small head, that has been sweeping through South
and Central America and the Caribbean and making its way north to
the United States.
In February, the World Health Organization declared Zika a global
health emergency. The connection between Zika and microcephaly came
to light last year in Brazil.
Brazil has now confirmed more than 1,800 cases of babies with
microcephaly that it considers are linked to Zika infections in the
mothers.
The Wolbachia bacteria is occurs naturally in many insect species
worldwide, and research has shown that it can significantly reduce
the capacity of mosquitoes to transmit viruses to humans.
But it doesn't occur naturally in Aedes aegypti, the mosquito
species largely responsible for transmitting a range of diseases
including Zika, dengue, chikungunya and yellow fever.
Over the past decade, international researchers working with the
Australian-led non-profit Eliminate Dengue Program (EDP) have found
a way to transfer Wolbachia into Aedes aegypti mosquitoes and get
them to pass it on to their offspring.
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When mosquitoes with Wolbachia are released into an area, they breed
with local mosquitoes and pass the bacteria on to future
generations. Within a few months, the majority of mosquitoes carry
Wolbachia and the effect is then self-sustaining.
Since 2011, field trials using this method have been carried out in
five countries and show that when a high proportion of mosquitoes in
an area carry Wolbachia, local transmission of viruses is halted.
Trevor Mundel, head of the Gates Foundation's global health
division, said he hoped the large-scale campaigns had the potential
to show Wolbachia as a "revolutionary form of protection against
mosquito-borne disease".
"It's affordable, sustainable, and appears to provide protection
against Zika, dengue, and a host of other viruses," he said in a
statement. "We're eager to study its impact and how it can help
countries."
(Reporting by Kate Kelland; Editing by Tom Heneghan)
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