Zika virus: new ways to fight mosquitoes needed after dengue failure, WHO says

At the conclusion of a three-day Zika research and developmentmeeting on Wednesday, WHO's Marie-Paule Kieny said that "evidenceis missing" that the classical ways of fighting dengue have madeany substantial dent in cases. She says the same challenge mightapply to Zika.

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"Everything that was done in the country to control [mosquitoes]apparently didn't work," said Jorge Kalil, director of the ButantanInstitute in Sao Paolo, Brazil, who attended the meeting.

"Theproblem right now is it's very difficult to fight the [mosquito],there are billions and billions of insects."

Kalil said Brazilian officials may try a more targeted approachcalling for more involvement from villages and individuals. Kalilwas also optimistic that the coming winter season might help reducemosquito populations.

"Certainly it is worth continuing to try to use this method forthe lack of other interventions, but what the scientists said isthat there is an urgent need to also put in place studies toevaluate whether it has a benefit or not," Kieny said.

Kieny also noted another possible complication: that othermosquito species beyond Aedes aegypti might spread Zika. She saidthat while scientists have observed that other mosquito species cancarry the virus, it's unclear if they can actually infect people.

Last month, WHO declared the explosive spread of Zika in theAmericas to be a global emergency, due to its link to the spike inthe number of babies born with abnormally small heads and the risein a rare neurological syndrome that can cause paralysis and death.

So far, Zika has triggered outbreaks in 41 countries, althoughconfirmed cases linking Zika to babies with birth defects have onlybeen seen in Brazil and French Polynesia. Nine countries havereported a spike in cases of Guillain-Barre syndrome, a neurologicalcondition that typically affects people after infections.

She said work is being done by more than 30 companies to developa better diagnostic Zika test, since current tests often mix up Zikaand dengue infections.