RIO DE JANEIRO (AFP) - Brazilian researchers said on Monday (Feb 15) that the discovery of Zika in the brains of babies with microcephaly adds to growing evidence of a link between the mosquito-transmitted virus and the birth defect.

"We have detected its presence in the brain tissue," Lucia Noronha, a pathologist from the Brazilian Society of Pathology, told AFP.

"The Zika virus caused brain damage and that reinforces evidence of a relationship between Zika and microcephaly," she said.

Earlier, Noronha's team at the PUC-Parana University was the first to discover Zika in the amniotic fluid of pregnant women - raising alarm over a link between the virus and microcephalic babies, who are born with damaged brains and abnormally small heads.

"We received samples of brain tissue from the Oswaldo Cruz Foundation. They're the same samples that were sent to the United States, where researchers at the Centers for Disease Control came to the same conclusion: that there is Zika in the fetus' brain," she said.

Brazil is hardest hit by a huge outbreak of Zika, with some 1.5 million people infected. Although in most cases there are few symptoms, the fear is that pregnant women who become infected risk having babies with the birth defect.

The Health Ministry says that between October and February there were 462 cases of microcephaly, up from an average of 150 previously. Another 3,852 cases are suspected.