ROBERT SIEGEL, HOST:
Zika - a little more than a year ago, most people had never heard of it. Then doctors in Brazil started to see lots of babies being born with malformed heads. They had microcephaly, a rare birth defect.
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UNIDENTIFIED MAN #1: (Speaking Brazilian Portuguese).
LOURDES GARCIA-NAVARRO, BYLINE: Normally, in a year, he tells me, you'd have maybe three or four cases. In 24 hours, when we asked around, there had been 11 in the city. And that was a shocking enough number, he says, that we realized something very serious was happening.
SIEGEL: That's NPR's Lulu Garcia-Navarro reporting last December. The virus became an international health emergency. It spread to our shores. Here's a father-to-be in Miami in August.
UNIDENTIFIED MAN #2: I want to be out planning to go baby shopping. And I'm waiting to see if my wife, who got sick with a rash after getting bitten by something on Miami Beach, has Zika or not.
SIEGEL: The more scientists learned about Zika, the more disturbing it seemed. NPR health correspondent Rob Stein joins us now to recap and tell us what to expect next year. And, Rob, let's start by taking a step back. What did scientists know about Zika a year ago?
ROB STEIN, BYLINE: Well, you know, Robert, I've been covering health for decades, and I had to google Zika when doctors in Brazil first started to raise alarm bells about it. Researchers really knew very little about the Zika. It was so obscure and was thought to be pretty harmless. It hadn't really been studied very much at all.
SIEGEL: Well, they've learned a lot about it since then. Bring us up to date about what's now known about the virus.
STEIN: When I went to Brazil last February, the key question was - was Zika causing microcephaly? And now we know for sure, yes, Zika can cause microcephaly. And that makes it the first virus that's spread by a mosquito that can cause a serious birth defect. And they also know how it does that. And the more scientists learn Zika, really, the more disturbing it becomes. They're really - it's becoming clear that microcephaly is probably just the tip of the iceberg.
SIEGEL: There are other problems caused by Zika.
STEIN: Lots of other problems. Babies can be born with deformed limbs. They can have seizures. They can be deaf - blindness. There's a whole range of problems that Zika can cause.
SIEGEL: Well, those are things that we know or scientists know about Zika now. What are some things that they still don't know?
STEIN: There are huge open questions. I mean, you know, a big one, obviously, is we're still trying to develop a vaccine. And there's some promising work going on there, but we're not there yet. There's no treatment for it, really. Another big question, I think, that a lot of women - pregnant women - have is - how risky is it, really? A lot of women catch Zika when they're pregnant, but their babies turn out fine. And the big question is - how often does it cause microcephaly and other birth defects?
Now there some recent research came out just last week that started to give us a hint of what the risk might be. One study from the United States found the risk to be about 4, 6 percent maybe for microcephaly and birth defects, maybe as high as 11 percent if women are infected in the first trimester. But then there was another study out of Brazil that found that maybe close to half of pregnancies could end up with some sort of problem if women get infected when they're pregnant. So the bottom line on that is we really don't know.
And another big question is - is it going to cause problems later in life? We've discovered recently that the virus can continue to reproduce in the brains of babies after they're born. That raises the possibility that could cause damage after they're born and even in young children if they get infected.
SIEGEL: And looking ahead to next year, Rob, what can we expect to be hearing about Zika?
STEIN: Yeah, so scientists are keeping a close eye now on Latin America to see what's going to happen. Are we going to see big epidemics, big outbreaks like last year? We might in places where we didn't see a lot of Zika this past year. Doctors are also worried about Puerto Rico, where we saw a lot of infections this past year. And the women who got infected are starting to give birth now. Will we see a big upsurge in microcephaly? That's a big concern. And also, you know, the question is on the continental United States - scientists think that we're probably will continue to see Zika come back year after year. It'll become kind of a chronic problem - not any big epidemics, but small clusters and outbreaks every year probably going forward for many years.
SIEGEL: OK. NPR health correspondent Rob Stein, thanks.
STEIN: Sure. Nice to be here.
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