STEVE INSKEEP, HOST:
This is a story about making sure we know what we think we know. The World Health Organization says there is now strong scientific consensus that the Zika virus can cause microcephaly in infants. In the United States, the Centers for Disease Control and Prevention agrees there is a link. Now, sure, we've been talking about this for months, but it has also taken months of work to confirm the link between Zika and brain damage in babies. Let's start our coverage with NPR's Michaeleen Doucleff.
MICHAELEEN DOUCLEFF, BYLINE: Last fall, Brazil reported a startling increase in babies born with extremely small heads. There's been growing evidence that Zika is involved, that the virus damages fetuses during pregnancy. But so far, all the evidence is circumstantial.
Scientists have found virus in the brains of affected babies, and during pregnancy, a Zika infection appears to raise the risk a baby will have microcephaly. But the big question has been is Zika really the culprit? Now, the World Health Organization and the Centers for Disease Control and Prevention say there's enough evidence to say, yes, Zika is linked to microcephaly.
ANN SCHUCHAT: At this point, the most pressing question people want answered is, if I get Zika infection during pregnancy, what are the chances my baby's going to be affected?
DOUCLEFF: That's Ann Schuchat, the deputy director of the CDC.
SCHUCHAT: And we really feel a sense of urgency to both answer that question and to help stop the spread of the virus.
DOUCLEFF: She says Zika may be linked to other types of birth defects, miscarriages and stillbirths. But more research is needed to figure out how much danger a fetus is in if a pregnant woman becomes infected. Michaeleen Doucleff, NPR News.
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