1.5 million Brazilians may have been infected with the mosquito-borne virus Zika. The USA. and other countries are reporting cases of news too. But what is exaclty the Zika virus? And why is a threat to pregnant women? Babies are born with birth defects.More 2,700 with microcephaly are born in Brazil in 2015. Brazilian health officials are convinced that this is related to the sudden outbreak of Zika virus. View the video to understand more about this virus .