Genes, bugs and radiation: WHO backs new weapons in Zika fight

Reuters

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A Brazilian soldier uses salt in an effort to kill off any larvae of the Aedes aegypti mosquito as he conducts an inspection at a house in Porto Alegre, Brazil, February 15, 2016. Photo: Reuters/Lunae Parracho A Brazilian soldier uses salt in an effort to kill off any larvae of the Aedes aegypti mosquito as he conducts an inspection at a house in Porto Alegre, Brazil, February 15, 2016. Photo: Reuters/Lunae Parracho

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Countries fighting the Zika virus should consider new ways to fight disease-carrying mosquitoes, including testing the release of genetically modified insects and bacteria that stop their eggs hatching, the World Health Organization said on Tuesday.
"Given the magnitude of the Zika crisis, WHO encourages affected countries and their partners to boost the use of both old and new approaches to mosquito control as the most immediate line of defense," it said.
The WHO also highlighted the potential of releasing sterile irradiated male mosquitoes, a technique that has been developed at the United Nations' International Atomic Energy Agency (IAEA).
Zika, which is now sweeping the Americas, is transmitted primarily by the Aedes aegypti mosquito, which the Geneva-based U.N. health body described as an "opportunistic and tenacious menace".
Many scientists believe Zika could be linked to microcephaly, or abnormally small heads, in newborns and a serious neurological disorder in adults called Guillain-Barre syndrome.
"If these presumed associations are confirmed, the human and social consequences for the over 30 countries with recently detected Zika outbreaks will be staggering," the WHO said.
Fighting the infection at source, by eliminating as far possible the mosquitoes responsible for transmission, is moving up the public health agenda, especially as the same insects also transmit dengue, chikungunya and yellow fever.
While spraying with insecticide can provide part of the solution, WHO experts said they also recommended evaluating newer tools, including a genetically modified prototype mosquito developed by Oxitec, the British subsidiary of Intrexon.
The male mosquitoes are modified so their offspring will die before reaching adulthood and being able to reproduce.
 Daniele Santos, 29, holds her son Juan Pedro who is 2-months-old and born with microcephaly, after bathing him at their house in Recife, Brazil, February 9, 2016. Photo: Reuters/Nacho Doce
The WHO said its Vector Control Advisory Group recommended further field trials of the technique, following promising previous tests in the Cayman Islands.
Another option involves the mass release of male insects that have been sterilised by low doses of radiation, which the IAEA has already used to control agricultural insect pests.
An alternative approach uses Wolbachia bacteria, which do not infect humans but cause the eggs of infected females to fail to hatch. Mosquitoes carrying Wolbachia have already been released to reduce dengue and the WHO said large-scale field trials would be initiated soon.
Much remains unknown about Zika, including whether the virus actually causes microcephaly. The WHO believes the suspected link could be confirmed within weeks.
Brazil is investigating more than 4,300 suspected cases of microcephaly. Researchers have confirmed more than 460 of these cases as microcephaly and identified evidence of Zika infection in 41 of them.
 

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