Brasilia: Brazil is losing the battle against the mosquito spreading the Zika virus, President Dilma Rousseff said, calling for a national effort to eradicate the insect.

‘We do not have a vaccine for Zika yet. The only thing we can do is fight the mosquito,’ she told reporters during a visit to a command center for the Zika crisis.

The virus has been linked to thousands of cases of babies being born in Brazil with microcephaly-meaning they have abnormally small heads and brains that have not developed properly.

Rousseff said tests for the development of a vaccine will begin next week at the Butantan Institute, one of Brazil’s leading biomedical research centers in Sao Paulo.

Experts say it could take years to come up with a vaccine for Zika given the lack of medical knowledge about the virus, though one leading developer said on Thursday that a vaccine for emergency use could be ready before year-end.

Rousseff called on Brazilians to eliminate still water in puddles and open storage tanks in their homes where the insect breeds.

On 13 February, more than 200,000 soldiers will join a nationwide effort to eliminate mosquito infestations.

The Aedes aegypti mosquito that carries Zika also spreads the dengue virus, which infected 1.65 million people in Brazil last year, 863 of whom died, in the country’s worst outbreak of the tropical disease.

Brazil eradicated the mosquito in the 1950s using chemicals that are now banned, officials said.