The Zika virus was first discovered nearly 70 years ago, but only in this most recent outbreak has it caused so much worldwide concern.



The virus is transmitted via mosquito. It spread from Africa into Asia, and onto the Pacific Islands, before eventually reaching the Americas.

There have been outbreaks of Zika in the past. But the virus has never before been linked with microcephaly — a birth defect characterized by an abnormally small head that can cause developmental issues.



Here's a look at the timeline of the Zika virus, from discovery to worldwide concern:



