It's Official: Zika virus causes birth defects

US health officials say there's no longer any doubt that the Zika virus causes severe birth defects.

Experts had been cautious about making a definitive link despite a surge of babies born with a rare birth defect in Brazil during a Zika outbreak. The virus is mainly spread by mosquitoes, and no mosquito-borne virus had ever been known to cause birth defects.

But on Wednesday, the Centers for Disease Control and Prevention said there's enough evidence now to declare Zika the cause of a birth defect called microcephaly and other brain abnormalities.

CDC officials said their advice to pregnant women won't change. Pregnant women should avoid traveling to places where the Zika virus is spreading, mostly in Latin America and the Caribbean.