UNICEF calls for immediate action against Zika virus

"And we need to engage with communities on how to stop the mosquito that is carrying and and transmitting this virus," she said.

More than 4,000 registered cases of microcephaly in newborn babies in Brazil have been reported between October 22, 2015 and January 26, 2016, according to UNICEF, compared to just 147 cases in the whole country in 2014.

"Although there is still no conclusive evidence of the causal link between microcephaly and the Zika virus, there is enough concern to warrant immediate action," said Papowitz.

Babies born with microcephaly have much smaller heads than expected. Depending on how severe the microcephaly is, they may also have other problems including developmental delay, intellectual disabilities, and hearing and vision loss, according to the US Centre for Disease Control.

UNICEF is launching an appeal for nearly $9 million to limit the spread of the virus and provide support to mothers and babies at risk of microcephaly.

Although the sharp increase in microcephaly has only so far been reported in Brazil, UNICEF is also increasing its support to the countries surrounding Brazil, as a precaution.

The World Health Organisation (WHO) declared on Monday that the cluster of microcephaly cases and other neurologic disorders reported in Brazil constituted a public health emergency of international concern.