Science Vs - Zika

Episode Date: September 30, 2016

Since 2015 there have been Zika outbreaks reported in sixty countries. So, where did Zika come from? What happens when you get infected? How worried should you be?And why has Zika has become such a problem recently? To find out, we speak to Assoc. Prof. Desiree LaBeaud, Dr Cathy Spong, Dr Andrew Haddow, and New York Times health reporter Donald McNeil Jr. Credits This episode has been produced by Diane Wu, Wendy Zukerman, Heather Rogers, Caitlin Kenney, and Shruti Ravindran. Our senior producer is Kaitlyn Sawrey. Edited by Annie-Rose Strasser. Sound design and music production by Matthew Boll, mixed by Martin Peralta. Music written by Martin Peralta and Bobby Lord. Our Sponsors Prudential – Download the MapMyRun app and join the Prudential 4.01K challenge. When you do, pledge to save at least 1% or more of your annual income for retirement and run and log 4.01K to be eligible to win a prize. Squarespace – The easiest way to create a beautiful website, portfolio or online store. Use the offer code “SCIENCE VS” to get 10% off your first purchase. Wealthsimple – Investing made easy. Get your first $10,000 managed for free. Selected ReferencesFirst case of Zika reported in Nigerian girl N. McNamara, Trans R Soc Trop Med Hyg, 1954.Donald McNeil Jr’s recent book on Zika epidemic McNeil, DG “Zika: The emerging epidemic,” W. W. Norton and Co, 2016Interactive history of Zika from the World Health OrganizationZika virus may linger in the vagina Prisant, N et al “Zika virus in the female genital tract,” The Lancet 2016Estimated risk of microcephaly if you get zika when pregnant is between one and 13% Johansson, M et al “Zika and the Risk of Microcephaly,” New England Journal of Medicine, 2016First report that Zika can be spread through sex (confirming Andrew Haddow's hunch over a beer in Senegal) Foy, BD et al “Probable Non–Vector-borne Transmission of Zika Virus, Colorado, USA,” Emerging Infectious Diseases, 2011U.S. Centers for Disease Control recommendations on ZikaWorld Health Organization recommendations on Zika Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Think of it as your guide for all things AI, with the most human issues at the center. Join me every Wednesday for Pioneers of AI. And don't forget to subscribe wherever you tune in. Hi, I'm Wendy Zuckerman and you're listening to Science Versus from Gimlet Media. This is the show where we pit facts against friggin' mosquitoes. Today, we're tackling one of the biggest science puzzles of 2016, the explosion of the Zika virus. This year was the first time that many people would have heard of the Zika virus.

We got a sobering update on Zika. Zika virus. The Zika virus and its potentially devastating consequences continues to spread. Warning that the Zika virus appears to be a lot scarier than first thought. Photos of babies born with small heads, a condition called microcephaly,

have been dominating the news all year. And the cause? Zika. Now, it's clear that this virus is spreading. Since 2015, there have been Zika outbreaks reported in 60 countries, most recently in Singapore and Thailand. This news has put a lot of questions into a lot of people's minds. So today, we're going to be discussing some of them. Firstly, where did Zika come from? Second, what happens when you get infected? Third, how worried should you be if you live or are

travelling to a Zika-affected part of the world? And finally, why has Zika become such a problem recently? Since a lot of the science on Zika is still underway, we're bringing you a very different kind of Science Versus episode this week. There are just so many unknowns that it's too soon to be bringing you conclusions, so you won't be hearing the old bow-bow or ding-ding-ding-ding-ding that we just love so much on Science Versus. Instead, we're going to have a series of conversations with experts who study Zika. These are scientists

who look at how it spreads and how it attacks the human body. Okay, so let's start with Zika's origin story. New York Times reporter Donald McNeill Jr. wrote a book about the Zika epidemic earlier this year, and he's followed the recent outbreak very closely. We brought him in to talk about the discovery of Zika, and Donald told us that Zika was first found by researchers in 1947 in the dense Zika forest in Uganda. It was first spotted in a monkey that scientists had strategically placed as bait to attract mosquitoes. Here's Donald. In that forest, they had built a lot of towers,

which reached up into the treetops, and they had monkeys suspended in cages in those towers. They had the monkeys up there basically to be bitten by mosquitoes, and then they took them down every day and took their temperatures and checked on their general health. So the monkeys were in the cages on the treetops? At different heights. At different heights. Yep. Welcome to 1940s medical research. Absolutely. And this was completely ethical at the time. So Risu 766 had a fever and they brought it down, took it to the lab and did a blood draw. This was a monkey with the poetically titled name 766. Oh, but you know, virtually all research monkeys are known by their numbers.

So they pulled down. They pulled down the monkey. It had a temperature. So they decided to start looking in its blood to see what it had. And the actual process of figuring out what this was and the fact that it wasn't something already known, it wasn't yellow fever, it wasn't dengue, it wasn't Semliki forest virus, it wasn't Buñamaro virus, it wasn't all these other viruses that they knew about, which nobody's ever heard of because they haven't come out of the forest and gotten us yet, but all of which could. To do that work took several years.

Ultimately, they realized, hey, it's something new, and they named it Zika virus after the forest where the monkey had been infected. Do we know who was the first human patient to get sick with Zika? Was there a patient zero? We know who the first human in whom the Zika virus was discovered. She was a 10-year-old girl in Nigeria. They did some interesting research then where they actually drew blood from an entire village near the lab in Nigeria to see if they had what we now know are antibodies to Zika, and like 60% of the village did. Okay, so the fact that 60% of the village had antibodies to Zika suggests that those people were actually infected with the virus at one point in their lives.

And Donald says that even though Zika wasn't discussed in the scientific community until around the 1950s, Zika has probably been around parts of Africa for thousands of years, infecting monkeys and people. But Donald says that Zika really wasn't considered to be so scary. That Nigerian girl, she had a headache and a fever, but that was about it. It was a relatively mild disease. There was a scientist who deliberately gave himself Zika in order to describe the effects. Your opinions. They just got to make it about them, don't they?

Yeah. He injected himself and then described the effects on himself. But it was a relatively mild disease. Okay, so after this buzz of research, no pun intended, some pun intended, for the next six decades, Zika was only mentioned about a dozen times in the scientific literature. And when it was, it was describing just a few people who were infected in Senegal, Pakistan, Indonesia, Cambodia. But no-one got that sick.

No deaths, no hospitalisations, just fever, rashes and chills. And again, not that many people got infected at once. But then in 2007, Zika turns up in a big way on the island of Yap. Yap is a tiny island in the Pacific Ocean just north of Papua New Guinea and east of the Philippines. So a doctor on Yap contacted the Centers for Disease Control and said, hey, we're having some sort of outbreak. Can you help me figure out what's going on? Here's Donald again.

So a team went from the CDC there and they, you know, started seeing patients and pulled blood and said, this is Zika virus. It hit the island. It hit 73% of the island population within six months and then disappeared. That was it, end of epidemic. And there hasn't been a case on Yap Island since.

In Yap, did we start to see serious complications, microcephaly, things like that? No. In Yap, it was considered a mild virus. So how did we get from hundreds of people on an island in the Pacific with just flu-like symptoms to the situation that we have now? Well, the first hint that Zika could become serious was

when the infection hit French Polynesia. This was in 2013. It was estimated that 30,000 people, roughly 10% of the population, went to the doctor because of Zika infections. And it was during this outbreak that doctors started seeing an unusual increase in another condition, Guillain-Barre syndrome. This is a temporary and very rare disease which can lead to paralysis and it can come on very suddenly. Usually, maybe a couple of people on these islands might be affected by this in a year. But during the outbreak, 41 people with Zika infections got it. Then we started hearing about Zika hitting Brazil. By the end of 2015, the Brazil Ministry of Health estimated

that between 500,000 to 1.5 million people were infected with Zika. And then things got worse. Their small faces number in the thousands in Brazil. Their mothers worried about developmental delay because of microcephaly. And how did the Brazil government, because they were the first to realize this connection.

It was actually individual doctors in Brazil who noticed it. Doctors who worked in the pediatric intensive care units suddenly began saying to each other, hey, I've got five babies with microcephaly in my unit. And actually, one of them was a mother-daughter team. They were both pediatric intensive care specialists at different hospitals. And they began talking to each other and saying, I've got seven in my hospital. I normally don't see a baby with microcephaly more than once a year or once every couple of years. Something's going on.

And so the doctors began consulting with each other and they realized that something terribly alarming was going on. The doctors in Brazil started to suspect that Zika was causing the microcephaly pretty much because of the timing. A bunch of new cases of Zika and then several months later, a bunch of new cases of microcephaly. So to explain how a mother being bit by a mosquito can suddenly produce babies with abnormally small heads, we talked to Desiree Lebeau, an associate professor of paediatric infectious diseases at Stanford University. Desiree specialises in diseases spread by mosquitoes, and she loves her job and loves what she studies. I'm an arborologist. So all arborologists love their arboviruses. What exactly is an arbovirus? Yeah, so an arbovirus stands for arthropod-borne virus. So this is a virus that uses a blood-sucking

arthropod to complete its life cycle. I study ones that are spread mainly by mosquitoes, but you can have other arboviruses that are spread by other arthropod vectors, like ticks and other insects. Now, tell me how exactly, I mean, I know there's lots of unknowns here, but what do we know? How exactly does the Zika virus cause microcephaly? So right now the thinking is that when a woman is infected, you know, she has the virus in her bloodstream, that virus can then cross over the

placental barrier into the placenta, and then it travels into the developing fetus, and it has sort of what we call neurotropism. So it actually is sort of drawn to the neural structures of the developing fetal brain. And so it infects those structures, you know, inhibiting their normal growth processes. Microcephaly is one aspect of the congenital Zika virus syndrome. But as time goes on, you know, we're starting to understand more and more of the entire bell-shaped curve. So when you say a bell-shaped curve, you mean there might be more subtle things going on rather than just microcephaly? Absolutely. So microcephaly is an easy thing to see, right? When the child is born and their head is very small, it's an easy thing for someone to pick up. But there are

probably going to be more and more subtle effects of Zika virus infection on babies. Probably not all those babies will have microcephaly. Maybe some will have hearing deficits, some may have vision deficits, some may have other learning problems or other deformities within the brain. And I wasn't around when the rubella virus was found to be a congenitally exposed virus and cause problems with babies whose moms happened to get rubella during pregnancy. But I was told in the 50s and 60s when that was going on that yes, initially they saw microcephaly, but then as time went on, they started to realize,

oh, there were other eye complications that are due to rubella. There are heart complications that are due to rubella and so forth. And so that came out later. And I think that's just what we'll find with Zika. I think microcephaly is sort of like the tip of the iceberg, and we'll probably find a lot of other long-standing complications from in utero exposure. And what about in adults? Are we seeing that Zika likes to attack the brains

of adults as well? Many, many arboviruses are able to cause infection of the brain because a lot of them are so neurotropic. And so it's possible that Zika virus will join its friends, the other arboviruses, and be able to cause these sort of spectra of disease in adults. But what I can say is that it does look like Zika virus has been associated with increased risk of Guillain-Barre syndrome. Remember that rare form of paralysis, Guillain-Barre syndrome? Well, during the Zika outbreak in Brazil, they did see more of it. Still very rare, but it did pop up more and more.

It's a reversible phenomenon. Usually you aren't left with long-standing health complications after you suffer from Guillain-Barre, but you do need to be supported during that time when you're most ill. Like from the virus's perspective, why is it so attracted to the brain and the nerve system? What's it doing once it's there? I'm not sure if we know that exactly. At this time, there are lots of people working on, you know, how does it cross the placental barrier? Desiree told us that one of the big ideas about how Zika is causing microcephaly is this. Zika gets inside brain cells

by unlocking what are called receptors on the cells of fetuses developing brains. You can think of receptors as little locks that protect the cells and to get inside these cells, you need a key. Zika seems to have that key. And that means that Zika can get inside fetuses' brains and cause havoc. Yes, exactly. So it could be that, yeah, the Zika virus has the key and then all of these early brain cells have the lock and does the placenta. So the virus is actually able

to use that key lock to get across the placental barrier and then set up shop in the developing brain. Is the Zika virus replicating in the brain cells as well? Yes. Can you take us through that process? Like, does it use human cells to make itself replicate? Yeah, that's usually what viruses do. So they sort of set up shop and make your cells a viral factory. It doesn't integrate into your DNA. It just comes in, it sets up shop and it kills the cell that it set the shop up in. Tell me, there's lots of concern out there. How worried should people be? So what are the chances that your baby will get microcephaly if you're infected with Zika and you're pregnant? We don't know the numbers. I can't say what the risk is.

I would say for pregnant women here in the U.S., you want to avoid being in an area that's having Zika virus transmission right now because we don't know those answers yet. And there isn't a 100% way that you can protect yourself from mosquitoes. We can try and do our very best with, you know, protecting ourselves using personal protective equipment, wearing pants and long

sleeves, wearing DEET or picaridin, you know, some effective mosquito repellent. But, you know, there's not 100% chance that you're going to protect yourself completely, right? And so if you can avoid traveling to those places, you should, especially when you're pregnant. As for a healthy adult with a normal immune system, if you get Zika virus infection, this is probably unlikely to do you great harm. Quick note, 80% of people infected with Zika don't even show symptoms. No outward physical signs at all. Okay, carry on, Desiree. You are sick for a few days with fever. you might have an itchy rash and some red eyes and you might feel unwell for a few days, but then your body clears the

virus and then and you get back to your normal health after. You know, if you're one of the unlucky few who has a severe complication from Zika like Yann Baret, that will, you know, that that is it can lead to severe disease, but most people are going to just have the sort of easier week-long, you know, febrile syndrome from it. And so if you plan to get pregnant in one or two or three years, would it be a problem to be infected with Zika now? No, I don't believe so. Because if you're a healthy adult, you're just going to have virus in your bloodstream for a few days, and then it'll go away. You'll clear the infection, and you'll make antibodies that will protect you from future infections.

And so you've actually protected yourself. It's not going to set up shop in your brain when you get infected and then be around years later when you want to have a baby. You will clear that virus within a week or two. So is it actually a good idea to get Zika now before you want to get pregnant so you have some kind of immunity? That's like, like have a, like a Zika party, like they used to throw chicken pox parties for kids back in the day. Yeah. I wouldn't recommend that. I think you should protect yourself, avoid, you know, avoid travel and, and wait for effective, you know, vaccines and, and therapeutics to come out. I wouldn't, I wouldn't suggest that everybody

should have a, throw a Zika party. Why not? Even though it's a relatively, you know, benign viral infection when you're a healthy adult, it's still terrible to get sick for that long. And I think that, you know, the risk for maybe severe disease would still be there also, even though it's small, it's still a risk. And so at this time, I think people should just, you know, be smart, travel wisely and protect yourself from mosquitoes. And so you think there is really no need to be concerned about having a Zika infection now and that infection staying in your body until even a month, if you want to get pregnant, even a month after infection? The CDC has come out with recommendations for this.

You probably want to wait three months after you've had your Zika virus infection to attempt to getting pregnant. And given there's quite a bit that we don't know about Zika, how can they be so confident with that recommendation? I think they're just looking at the evidence that they have now and trying to sort of give the best estimates. I think, you know, the reason why I can feel confident saying that Zika doesn't sit around, you know, and isn't ready to come and get your baby three years later is because again, your body clears this virus. This is not a virus like a herpes virus that would stay with you, stay within your cells and then rear its ugly head

when you get stressed out and then you get a cold sore. It's not that type of virus. It's not a DNA virus that's going to do that. This is a virus that's going to come in and, you know, kill the cells that it infects right then and then your body's going to deal with. This is a virus that's going to come in and, you know, kill the cells that it infects right then, and then your body's going to deal with it, and then it's over. With all the other arboviral infections, that's exactly what happens. You, you know, you get the infection, your body clears the infection, and then you're protected from that infection. There have been studies that have shown that the people who have Zika, that you can't even get a positive test result for Zika virus in your bloodstream, you know, if it's been seven days since your initial fever. It's already gone out of your

bloodstream. So there is evidence to support that the virus is gone pretty quickly after you get the infection. And so I think that's why the CDC and others feel pretty confident saying that, you know, there isn't going to be any harm to a fetus further on down the line once you've cleared your Zika virus infection. Just to clarify, the CDC recommends that women should wait at least eight weeks after possible exposure to Zika before trying to get pregnant. But to be sure, Desiree recommends three months. Now, Desiree acknowledges that right now we don't have any long-term studies on people infected with Zika, which means that even though she and other people who study viruses think that if you are infected with Zika today

and then get pregnant in a couple of months, your baby will be fine, there is no conclusive evidence of this. From her and other experts' understanding of these kinds of viruses in general though, they do think this is the case. But there is always a chance that a virus could break the rules and we won't know for sure if Zika is that bad boy until we study it fully. There are some signs that Zika might not play by the rules. In July, genetic material from the Zika virus was found in the mucus of a woman's vagina who had been infected by Zika. Now, it was found there 11 days after her symptoms set in.

At that point, there was no sign of the Zika virus in her blood or urine, just the genetic material of Zika in her vagina, which raised the possibility that Zika may stick around for longer than expected. And because this is all so new and when it comes to outbreaks of diseases, different experts, depending on their speciality, have different perspectives. We also spoke to Cathy Spong, an obstetrician and acting director of the National Institute for Child Health and Human Development. And we asked her about the CDC's recommendations to wait eight weeks after possible exposure to Zika

before trying to get pregnant. If a woman has had Zika, we don't have any evidence to say that once that time period has passed that she should have concerns for a future pregnancy. Then again, I would say we don't have a lot of data on it either. Are you happy with the evidence that we have on that at the moment to give that? This is the best information we have available. How confident are you in it?

It's the best information we have available. Kathy. I mean, the CDC has, these are the guidance based on the best information we have available. Depending on your perspective on life, you can take the unknowns and amplify them in your head or you can underplay them. But when it comes to disease, we tend to overplay them. So, I mean, there's always unknowns in everything we do. And so I think, yes, this is an unknown that is a little more, a little heightened in the sense that this is something that is new

that we don't have a lot of data on. That said, it's simply one of the many unknowns in pregnancy. After the break, Zika has been around for a very long time. So why is it spreading and causing these heartbreaking symptoms now. Welcome back. So, remember when those scientists first identified Zika in Uganda in 1947 by putting the monkeys up in the tree to get bit by mosquitoes? Well, if we've known about this disease since 1947, a disease that we just heard can do some really scary things to us,

especially in developing babies, why are we just starting to notice this disease now? How did we miss it? To help us answer this question, we turned to Andrew Haddow, a researcher at the United States Army Medical Research Institute for Infectious Diseases. Now, Andrew's grandfather just happens to be Alexander Haddow, one of the first scientists to isolate Zika back in the 1940s.

The first time I heard about Zika was probably when I was about three or four years old, from my father during my bedtime stories. And before we talk to Andrew about why we underestimated Zika, you need to know that he has carried on his grandfather's work by making another really big discovery about Zika. A discovery made in the late 2000s in Senegal. And it all started when his buddy Kevin, who's also a scientist, was telling Andrew about this weird illness that he and his mate got when they were working with mosquitoes. I was imagining it was over beer. It was. It was over a beer. It was over a beer. Yeah, kind of on a veranda looking out over a river. So I said, you know, Kevin, it sounds like you have both maybe had Zika virus.

We need to test your blood. And then he kind of leans back in his chair and just says, well, there's something else. And I was just like, you know, what else? Because I mean, it's just kind of like, what else could there be? And he's like, the other investigator's name was Brian Foy. And so he says, well, Brian, Brian's wife came down with the same signs and symptoms after he got back. And it's just like, what? And I mean, all of this together just kind of pointed to the likelihood of a sexual transmission event. There were some other signs and symptoms that pointed to the possibility. Like the fact they had sex? I'm sorry? Like the fact they had sex? Yes. Brian had noticed that there had been blood in his semen and that he had had, you know,

his prostate was inflamed and his wife came down with classic, what we would kind of call classic Zika signs and symptoms, fever, rash, et cetera. So this was kind of one of those things like, wow. I mean, I said, yeah, we really have to get your, her blood also. We need to, you know, we need to test this. And I said, you know, I really think that it's Zika. Because is this, is this really uncommon for this sort of virus? Yes. So before this, this diagnosis, there were no reports, to my knowledge, of sexual transmission of an arbovirus in the literature.

The closest was a report of Japanese encephalitis virus in the semen of boars. So this is just kind of way out there as things go. And so, you know, it was met with, I think I can say, a lot of scepticism in our community. Other studies have recently confirmed what Andrew first discovered, that Zika can be found in semen, and it stays in semen longer than it does in blood. In one report, a woman got infected with Zika through unprotected sex

about a month after her partner showed symptoms of Zika infection. So that means the virus was alive in her partner's semen for at least that long. As a result, the World Health Organisation recommends that men who travel to Zika-infected areas wait six months before having unprotected sex. Yep, six months. Got it?

Now, Andrew doesn't just probe his mate's sex life for his research. He's also been studying the genetics of the Zika virus over time. So we had a lot of questions for him. First off, though, why did this outbreak with the microcephaly and the paralysis happen now? Maybe the virus could have always done these things, but first of all, they weren't detected. So I think as we're seeing more cases, we're just getting a better understanding of really what the virus is capable of doing. It's not that it wasn't doing it in the past. It may

literally just be there weren't enough people studied to really know. The other part is in these areas where Zika virus is endemic, historically, women or girls would have likely been infected at a very young age before they ever even reached puberty. And what that means is they basically would have been immune when they were adults and when they were getting pregnant and having children. And that may also be a reason why we didn't see microcephaly in those regions before now. Honestly, I think that we owe a lot to a group of physicians in Brazil for really pushing the microcephaly, you know, at the time it was a hypothesis, forward and really bringing widespread attention to this issue. At first, it was, I'll tell you, it was met with a lot of skepticism in the, you know, scientific community. Why was there so much skepticism in the, you know, scientific community. Why was there so much skepticism?

Well, I think what happens is we all get tunnel vision. And, you know, this is what the virus does, and that's all it does. And it was the same with what we know now, that the case of sexual transmission, that was met with skepticism. Then you have Guillain-Barre syndrome, met with skepticism, then you have Guillain-Barre syndrome met with skepticism, and microcephaly met with skepticism. You know, we sometimes, we get so used to what we would maybe the norm that we forget that things change, and that we always have to be cognizant that these viruses aren't an evolutionary arms race, and they are trying to adapt to infect more hosts. So we have to be cognizant just because something hasn't done anything for, you know, 70 years doesn't mean that it can't do it in the future. Do you think it's possible that the Zika virus is mutating in

some way to make it easier to infect big populations? So there's just a lot we don't know about the virus. We're learning new things almost every week. But what I can say is it appears that the virus is overall pretty stable. So scientists have started tracking how Zika has changed genetically since it was first detected in 1947, and they have found minor differences in its genetic code. But so far, it's still not clear if Zika is evolving to become more dangerous necessarily or if it's basically the same old virus that just happened to find a continent of people

to make sick for the very first time. OK, so what have we learnt? First, where did Zika come from? Researchers first found it in Africa, and it's been there for probably thousands of years. Two, what happens when you get infected? There's rashes and fevers, and while there are some complications, most of the time the disease is pretty mild. In fact, 80% of people who get infected don't even show symptoms. But when you are pregnant, the virus can make a beeline for the foetus, and we're still trying to work out the full consequences of this.

Third, how worried should you be if you live or are travelling to a Zika-affected part of the world? Well, if you're not pregnant, you're not planning on getting pregnant and you're not planning on making anyone else pregnant anytime soon, there's probably no need to be that worried. But if you are thinking of getting pregnant, this is a real concern because we currently don't know the chance that your baby will have defects if you are infected. And finally, why has this new ugly side of Zika reared its head now? We don't exactly know.

One theory is that people in parts of Africa where the virus has been around for ages are now immune to it. And it was only when the virus hit a large population that has never been exposed before, but trouble struck. So, now that we have this problem, the big question is, of course, how to stop it. There are a few things that scientists are working on. They're seeking out a vaccine

and they're also trying to lower mosquito populations, potentially by releasing genetically modified mozzies. Male mosquitoes have been specifically crafted so that when they bonk female mosquitoes, the offspring will die young. That is, the mozzie babies won't be able to make it to adulthood and won't be able to create more mozzie babies. Theory goes that if you release enough of these genetically modified dud mosquitoes, the population of mozzies will drop to hopefully the point where the diseases won't spread anymore. Small trials conducted by the company that makes these mosquitoes, Oxitec,

found that releasing these guys could reduce the mozzie population by around 90%. In August, the FDA approved plans to release them into Florida, but the community over there will have to decide whether they want it or not. Thing is, even if we can get rid of 90% of the mosquitoes, there are still that cheeky 10% hanging around. Plus, the virus can spread while we are having sex. So probably the only way to protect us against Zika in the long term is to develop a vaccine. As of 2016, 29 different Zika vaccines were in development around the world. That's according to the World Health

Organization. One trial started in humans back in June, another in August. But right now, scientists are just checking to see if the vaccine causes any bad side effects. That's what happens in the first batch of volunteers. Even with huge international efforts to make a good vaccine as soon as possible, the National Institutes of Health estimates that the earliest date we'll see a vaccine is in 2018. So, what can you do right now if you live in an area impacted by Zika? Scientists recommend that you try to keep mosquitoes away the best way you can, and that means getting rid of open water in containers or blocked drains.

That's what the mozzies use to breed. Also, perhaps sleep beneath a net. You can pop on your air conditioner because mozzies don't like the cold. Also, wear long sleeves and use bug spray. OK, that's what we know for now. The research continues, as it always does, because this is science and this was Science vs Zika. This episode has been produced by Diane Wu, Heather Rogers,

Caitlin Kenney, Shruti Ravindran, and our senior producer is Caitlin Sorey. Edited by Annie Rose Strasser and fact-checked by Michelle Harris. Sound design and music production by Matthew Boll Mixed by Martin Peralta and Bobby Lord Music written by Martin Peralta and Bobby Lord For key references, head to our webpage Next week, we're tackling forensic science

On CSI, it looks so easy But how much can you really trust the science that gets presented in courtrooms? I'm Wendy Zuckerman. Back to you next time.