The Zika Virus Grew Deadlier With a Small Mutation, Study Suggests

By PAM BELLUCK and DONALD G. McNEIL Jr.SEPT. 28, 2017

Pedro Miguel Firmo de Lima, born with microcephaly in northeastern Brazil in October 2015, receiving a kiss from his grandmother, Fatima. Scientists believe the deadly strain of the Zika virus, which causes microcephaly, might be traced to a single genetic mutation that arose in the virus in 2013. Credit Adriana Zehbrauskas for The New York Times

It remains one of the great mysteries of the Zika epidemic: Why did a virus that existed for decades elsewhere in the world suddenly seem to become more destructive when it landed in Latin America?
Why did the Zika virus cause thousands of babies to be born with microcephaly, unusually small and damaged brains, when previous outbreaks in Africa and Asia seemed to cause much less harm? Read more.