Three pregnant women in Florida and two in Illinois - all of whom had traveled to South America - have tested positive for the Zika virus. Governments in South America and the Caribbean have asked women to avoid getting pregnant, and the CDC now warns US women of childbearing age not to travel to countries where the disease is spreading. That's because the Zika virus has been linked to a condition called microcephaly, where babies are born with small heads and incomplete brain development.
Wonder why you never heard about Zika until recently? That's because scientists used to consider it fairly harmless. Vox.com will get you up to date:
