U.S. health officials have concluded that infection with the Zika virus in pregnant women is a cause of the birth defect microcephaly and other severe brain abnormalities in babies.
"It is now clear, the CDC has concluded, that Zika virus does cause microcephaly," Tom Frieden, director of the U.S. Centers for Disease Control and Prevention, said in a conference call with reporters on Wednesday. "There isn't any doubt that Zika causes microcephaly."
U.S. and world health officials have been saying for some time that mounting scientific evidence points to the mosquito-born virus as the likely cause of the alarming rise in microcephaly in Zika-hit areas of Brazil. It had not been declared as the definitive cause until now.
Never before in history has a bite from a mosquito been seen as the cause of birth defects, Frieden said.