World Health Organization declares Zika outbreak in the Americas a health emergency

Detected in a number of returning travelers in the U.S. over the past month, the mosquito-transmitted Zika virus is rampant in Brazil, present in a number of Central American countries, and linked to birth defects in babies. The W.H.O. has declared it a world health emergency.

Read key facts about the disease here from the CDC. The CDC has travel warnings also.