It seems the number of cases of microcephaly in Brazil has increased, but only to 404 cases compared to the 25,000 cases in the US where there is no Zika virus.see here,in portuguese.
The increase in Brazil could be for many other health reasons, even due to under-reporting of cases. There is hardly any evidence of microcephaly victims who also have zika.
In Sao Paulo State, for example a big increase in microcephaly has been reported (compared to those reported in the past, 126 instead of 40), but nearly all in areas where Zika has not even been detected, never mind proved to have any relation.see here, in portuguese.
Also because Zika is a mild and difficult to detect virus it may well have existed in Brazil for decades and was only noticed in 2014.
The Free 