1.5 million Brazilians may have been infected with the mosquito-borne Zika virus. The U.S. and the other countries are reporting news cases also. But what exaclty is the Zika virus? And why it is a threat for pregnant women? The babies are born with birth defects.More than 2,700 are born in Brazil with microcephaly in 2015. Brazil's health officials are convinced that this is linked to the sudden outbreak of the Zika virus. Lets watch the video to understand more about this virus.