Margaret Chan praised the Brazilian government's efforts to stamp out mosquitoes and its coordination with various international bodies, including the WHO and the International Olympic Movement, ahead of the Games' August 5 kickoff.

We must "make sure that people who come here either for the Games as a visitor, as a participant or athletes, will get the maximum protection they need," she said after meeting with President Dilma Rousseff and several ministers in the capital Brasilia.

"And I'm confident that the government can do it."

But Chan also said it will be a long, hard fight to stamp out the virus, which is strongly suspected of causing a serious birth defect in babies born to mothers infected while pregnant.

"The Zika virus is very tricky, very tenacious, very difficult. And so is the Aedes aegypti mosquito," Chan said.

"We have learnt lessons from dengue and from chikungunya outbreaks in the past, so we should expect to see more cases, we should expect this is going to be a long journey."

Brazil is at the center of a Zika outbreak, with 1.5 million people infected, and authorities have also recorded a spike in microcephaly, a congenital condition that causes abnormally small heads and hampers brain development.

"We reiterate our commitment to continued cooperation in the fight against diseases caused by the Aedes," Rousseff said on Twitter.

"We'll do so cooperating on vaccine development, and in collecting data and information that can help identify the precise link between the Zika virus and microcephaly."

(Extracts from AFP)