Zika

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Hi, I'm Wendy Zuckerman and you're listening to Science Versus
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from Gimlet Media. This is the show where we pit
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facts against friggin' mosquitoes.
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Today we're tackling one.
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Of the biggest science puzzles of 2016, the explosion of
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the Zika virus. This year was the first time that
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many people would have heard of the Zika virus.
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We got a sobering update on Zika.
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Zika virus.
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The Zika virus and its potentially devastating consequences continues to spread.
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Warning that the Zika virus appears to be a lot
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scarier than first thought.
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Photos of babies born with small heads, a condition called microcephaly,
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have been dominating the news all year.
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And the cause? Zika.
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Now, it's clear that this virus is spreading. Since 2015,
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there have been Zika outbreaks reported in 60 countries, most
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recently in Singapore and Thailand. This news has put a
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lot of questions into a lot of people's minds. So today,
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we're going to be discussing some of them. Firstly, where
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did Zika come from? Second, what happens when you get infected? Third,
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how worried should you be if you live infected? or
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are travelling to a Zika-affected part of the world? And finally,
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why has Zika become such a problem recently? Since a
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lot of the science on Zika is still underway, we're
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bringing you a very different kind of Science Versus episode
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this week. There are just so many unknowns that it's
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too soon to be bringing you conclusions, so you won't
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be hearing the old bam-bam or ding-ding-ding-ding-ding that we just
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love so much on Science Versus. Instead, we're going to
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have a series of conversations with experts who study Zika.
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These are scientists who look at how it spreads and
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how it attacks the human body. Okay, so let's start
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with Zika's origin story. New York Times reporter Donald McNeil Jr.
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wrote a book about the Zika epidemic earlier this year,
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and he's followed the recent outbreak very closely. We brought
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him in to talk about the discovery of Zika, and
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Donald told us, that Zika was first found by researchers
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in 1947 in the dense.
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Zika forest in Uganda.
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It was first spotted in a monkey that scientists had
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strategically placed as bait to attract mosquitoes.
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Here's Donald.
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In that forest, they had built a lot of towers
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which reached up into the treetops and they had monkeys
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suspended in cages in those towers. They had the monkeys
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up there basically to be bitten by mosquitoes. And then
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they took them down every day and took their temperatures
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and checked on their general health.
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So the monkeys were in the cages.
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Yes.
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On the treetops.
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At different heights.
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At different heights.
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Yep.
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Welcome to 1940s medical research.
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Absolutely.
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And this was completely ethical at the time. So Risu
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766 had a fever and they brought it down, took
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it to the lab and did a blood draw.
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This was a monkey with the poetically titled name.
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Yes.
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766.
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Oh, but, you know, virtually all research monkeys are known
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by their numbers.
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So they pulled down.
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They pulled down the monkey. It had a temperature. So
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they decided to start looking in its blood to see
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what it had. And The actual process of figuring out
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what this was and the fact that it wasn't something
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already known, it wasn't yellow fever, it wasn't dengue, it
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wasn't semliki forest virus, it wasn't bunyamera virus, it wasn't
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all these other viruses that they knew about, which nobody's
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ever heard of because they haven't come out of the
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forest and gotten us yet, but all.
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Of which could.
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To do that work took several years. Ultimately, they realized, hey,
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it's something new, and they named it Zika virus after
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the forest where the monkey had.
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Do we know who was the first human patient to
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get sick with Zika?
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Was there a patient zero?
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We know who the first human in whom the Zika
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virus was discovered. She was a 10-year-old girl in Nigeria.
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They did some interesting research then where they actually drew
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blood from an entire village near the lab in Nigeria
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to see if they had what we now know are
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antibodies to Zika, and like 60% of the village did.
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OK, so the fact that 60% of the village had
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antibodies to Zika suggests that those people were actually infected
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with the virus at one point in their lives.
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And Donald says that even though Zika.
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Wasn't discussed in the scientific community until around the 1950s,
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Zika has probably been around parts of Africa for thousands
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of years, infecting monkeys and people. But Donald says that
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Zika really wasn't considered to be so scary. That Nigerian girl,
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she had a headache and a fever, but that was
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about it.
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It was a relatively mild disease. There was a scientist
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who deliberately gave himself Zika in order to describe the effects.
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Europeans, they just got to make it about them, don't they?
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Yeah.
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He injected himself and then described the effects on himself.
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But it was a relatively mild disease.
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Okay, so after this buzz of research, no pun intended,
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some pun intended, For the next six decades, Zika was
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only mentioned about a dozen times in the scientific literature.
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And when it was, it was describing just a few
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people who were infected in Senegal, Pakistan, Indonesia, Cambodia. But
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no one got that sick, no deaths, no hospitalisations, just fever,
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rashes and chills. And again, not that many people got
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infected at once.
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But then in 2007, Zika turns up in a big way.
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on the island of Yap.
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Yap is a tiny island in the Pacific Ocean, just
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north of Papua New Guinea and east of the Philippines.
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So a doctor on Yap contacted the Centers for Disease
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Control and said, hey, we're having some sort of outbreak.
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Can you help me figure out what's going on? Here's
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Donald again.
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So a team went from the CDC there and they,
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you know, started seeing patients and pulled blood and said,
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this is Zika virus. It hit the island. It, it, um,
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hit 73% of the island population within six months and
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then disappeared. That was end of epidemic. And there hasn't
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been a case on Yap Island since.
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In Yap, did we start to see serious complications, microcephaly.
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Things like that?
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No.
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In Yap, it was considered a mild virus.
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So how did we get from hundreds of people on
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an island in the Pacific with just flu-like symptoms to
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the situation that we have now? Well, the first hint
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that Zika could become serious was when the infection hit
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French Polynesia. This was in 2013. It was estimated that 30,000 people,
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roughly 10% of the population, went to the doctor because
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of Zika infections. And it was during this outbreak that
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doctors started seeing an unusual increase in another condition, Guillain-Barre syndrome.
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This is a temporary and very rare disease which can
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lead to paralysis and it can come on very suddenly. Usually,
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maybe a couple of people on these islands might be
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affected by this in a year. But during the outbreak,
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41 people with Zika infections got it. Then we started
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hearing about Zika hitting Brazil. By the end of 2015,
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the Brazil Ministry of Health estimated that between 500,000 to 1.5
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million people.
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Were infected with Zika. And then things got worse. Their
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small faces number in the thousands in Brazil.
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Their mothers worried about developmental delay because of microcephaly.
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And how did the Brazil government, because they were the
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first to realize this connection.
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It was actually individual doctors in Brazil who noticed it.
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Doctors who worked in the pediatric intensive care units suddenly
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began saying to each other, hey, I've got five babies
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with microcephaly in my unit. And actually, one of them
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was a mother-daughter team. They were both pediatric intensive care
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specialists at different hospitals. And they began talking to each
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other and saying, I've got seven in my hospital. I
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normally don't see a baby with microcephaly more than once
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a year or once every couple of years. Something's going on.
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And so the doctors began consulting with each other. And
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they realized that something terribly alarming was going on.
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The doctors in Brazil started to suspect that Zika was
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causing the microcephaly pretty much because of the timing. A
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bunch of new cases of Zika, and then several months later,
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a bunch of new cases of microcephaly. So, to explain
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how a mother being bit by a mosquito can suddenly
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produce babies with abnormally small heads, we talked to Desiree Lebeau,
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an associate professor of paediatric infectious diseases at Stanford University.
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Desiree specializes in diseases spread by mosquitoes. And she loves
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her job and loves what she studies.
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I'm an arbovirologist. So all arbovirologists love their arboviruses.
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What exactly is an arbovirus?
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Yeah, so an arbovirus stands for arthropod-borne virus. So this
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is a virus that uses a blood-sucking arthropod to complete
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its life cycle. I study ones that are spread mainly
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by mosquitoes, but you can have other arboviruses that are
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spread by other arthropod vectors, like ticks and other insects.
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Now, tell me how exactly, I mean, I know there's
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lots of unknowns here, but what.
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Do we know?
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How exactly does the Zika virus cause microcephaly?
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So right now, the thinking is that when a woman
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is infected, she has the virus in her bloodstream. That
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virus can then cross over the placental barrier into the placenta.
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And then it travels into the developing fetus. And it
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has sort of what we call neurotropism. So it actually
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is sort of drawn to the neural structures of the
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developing fetal brain. And so it infects those structures. inhibiting
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their normal growth processes. Microcephaly is one aspect of the
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congenital Zika virus syndrome. But as time goes on, you know,
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we're starting to understand more and more of the entire
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bell-shaped curve.
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So when you say a bell-shaped curve, you mean there
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might be more subtle things going on rather than just microcephaly?
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Absolutely. So microcephaly is an easy thing to see, right?
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When the child is born and their head is very small,
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it's an easy thing for someone to pick up, but
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they're probably going to be more and more subtle. effects
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of Zika virus infection on babies. Probably not all those
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babies will have microcephaly. Maybe some will have hearing deficits.
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Some may have vision deficits. Some may have other learning
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problems or other deformities within the brain. And I wasn't
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around when the rubella virus was found to be a
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congenitally exposed virus and cause problems with babies whose moms
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happened to get rubella during pregnancy. But I was told
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in the 50s and 60s when that was going on, Yes, initially,
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you know, they saw microcephaly, but then as time went on,
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they started to realize, oh, there were other eye complications
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that are due to rubella. There are heart complications that
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are due to rubella and so forth. And so that
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came out later. And I think that's just what we'll
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find with Zika. I think microcephaly is sort of like
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the tip of the iceberg, and we'll probably find a
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lot of other longstanding complications from in utero exposure.
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And what about in adults?
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Are we seeing that Zika likes to attack the brains
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of adults as well?
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Many, many arboviruses are able to cause infection of the
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brain because a lot of them are so neurotropic. And
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so it's possible that Zika virus will join its friends,
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the other arboviruses, and be able to cause these sort
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of spectra of disease in adults. But what I can
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say is that it does look like Zika virus has
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been associated with increased risk of Guillain-Barre syndrome.
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Remember that rare form of paralysis, Guillain-Barre syndrome? Well, during
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the Zika outbreak in Brazil, they did see more of it.
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Still very rare, but it did pop up more and more.
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It's a reversible phenomenon. Usually you aren't left with long-standing
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health complications after you suffer from Guillain-Barre, but you do
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need to be supported during that time when you're most ill.
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Like, from the virus's perspective, why is it so attracted
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to the brain and the nerve system?
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What's it doing once it's there?
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I'm not sure if we know that exactly. At this time,
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there are lots of people working on, you know, how
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does it cross the placental barrier?
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Desiree told us that one.
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Of the big ideas about how Zika is causing microcephaly
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is this. Zika gets inside brain cells by unlocking what
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are called receptors on the cells of fetuses developing brains.
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You can think of receptors as little locks that protect
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the cells, and to get inside these cells, you need
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a key. Zika seems to have that key. And that
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means that Zika can get inside fetuses' brains and cause havoc.
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Yes, exactly. So it could be that, yeah, the Zika
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virus has the key and then all of these early
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brain cells have the lock and does the placenta. So
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the virus is actually able to use that key lock
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to get across the placental barrier and then set up
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shop in the developing brain.
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Is the Zika virus replicating in the brain cells as well?
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Yes.
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Can you take us through that process? Like, does it
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use human cells to make itself replicate?
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Yeah, that's usually what viruses do. So they sort of
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set up shop and make yourselves a viral factory. And
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then that, you know, that one cell will produce many, many,
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many viruses that will then go on to infect other
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cells and so forth. And in the case of Zika
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virus infection, unlike the herpes virus infections, it doesn't really
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stay behind and integrate in your host cell. genetic material.
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It doesn't integrate into your DNA. It just comes in,
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it sets up shop and it, you know, kills the
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cell that it set the shop up in.
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Tell me, there's lots of concern out there. How worried
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should people be? So what are the chances that your
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baby will get microcephaly if you're infected with Zika and
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you're pregnant?
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We don't know the numbers. You know, I can't say
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what the risk is. I would say for pregnant women
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here in the U.S., you want to avoid being in
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an area that's having Zika virus transmission right now, because
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we don't know those answers yet. And there isn't a
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100% way that you can protect yourself from mosquitoes. We
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can try and do our very best with protecting ourselves
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using personal protective equipment, wearing pants and long sleeves, wearing
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DEET or picaridin, some effective mosquito repellent, But, you know,
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there's not 100% chance that you're going to protect yourself completely, right?
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And so if you can avoid traveling to those places,
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you should, especially when you're pregnant. As for a healthy
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adult with a normal immune system, you know, if you
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get Zika virus infection, this is probably unlikely to do
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you great harm.
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Quick note, 80% of people infected with Zika don't even
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show symptoms. No outward physical signs at all.
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Okay, carry on, Desiree.
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You... are sick for a few days with fever, you
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might have an itchy rash and some red eyes, and
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you might feel unwell for a few days, but then
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your body clears the virus and you get back to
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your normal health after. You know, if you're one of
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the unlucky few who has a severe complication from Zika
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like Yann Baret, that will, you know, that is, it
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can lead to severe disease, but most people are going
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to just have the sort of easier week-long, you know,
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febrile syndrome from it.
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And so if you plan to get pregnant in one
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or two or three years, would it be a problem
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to be infected with Zika now?
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No, I don't believe so. Because if you're a healthy adult,
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you're just going to have virus in your bloodstream for
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a few days and then it'll go away. You'll clear
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the infection and you'll make antibodies that will protect you
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from future infections. And so you have actually you've protected yourself.
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It's not going to set up shop in your brain
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when you get infected and then be around years later
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when you want to.
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Have a baby.
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You will clear that virus within a week or two.
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So is it actually a good idea to get Zika
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now before you want to get pregnant so you have
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some kind of immunity?
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That's like when they have a Zika party like they
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used to throw chicken pox parties for kids back in
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the day. Yeah. Yeah. I wouldn't recommend that. I think
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you should protect yourself, avoid travel, and wait for effective
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vaccines and therapeutics to come out. I wouldn't suggest that
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everybody should throw a Zika party.
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Why not?
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Even though it's a relatively benign... viral infection when you're
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a healthy adult, it's still terrible to get sick for
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that long. And I think that the risk for maybe
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severe disease would still be there also. Even though it's small,
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it's still a risk. And so at this time, I
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think people should just be smart, travel wisely, and protect
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yourself from mosquitoes.
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And so you think there is really no need to
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be concerned about having a Zika infection now and that
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infection staying in your body until... even a month if
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you want to get pregnant, even a month after infection.
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The CDC has come out with recommendations for this. You probably,
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you know, want to wait three months after you've had
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your Zika virus infection to attempt to getting pregnant.
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And given there's quite a bit that we don't know
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about Zika, how can they be so confident with that recommendation?
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I think they're just looking at the evidence that they
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have now and trying to sort of give the best estimates.
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I think, you know, the reason why I can feel
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confident saying that Zika doesn't sit around, you know, and
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isn't ready to come and get your baby three years
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later is because, again, your body clears this virus. This
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is not a virus like a herpes virus that would
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stay with you, stay within your cells, and then rear
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its ugly head when you get stressed out, and then
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you get a cold sore. It's not that type of virus.
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It's not a DNA virus that's going to do that.
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This is a virus that's going to come in and,
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you know, kill the cells that it infects right then,
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and then your body is going to deal with it,
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and then it's over. With all the other arboviral infections,
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that's exactly what happens. You get the infection, your body
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clears the infection, and then you're protected from that infection.
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There have been studies that have shown that the people
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who have Zika, that you can't even get a positive
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test result for Zika virus in your bloodstream if it's
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been seven days since your initial fever. It's already gone
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out of your bloodstream. So there is evidence to support
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that the virus is gone pretty quickly after you get
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the infection.
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And so.
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I think that's why the CDC and others feel pretty
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confident saying that, you know, there isn't going to be
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any harm to a fetus further on down the line
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once you've cleared your Zika virus infection.
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Just to clarify, the CDC recommends that women should wait
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at least eight weeks after possible exposure to Zika before
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trying to get pregnant. But to be sure, Desiree recommends
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three months. Now, Desiree acknowledges that right now we don't
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have any long-term studies on people infected with Zika, which
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means that even though she and other people who study
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viruses think that if you are infected with Zika today
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and then get pregnant in a couple of months, your
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baby will be fine, there is no conclusive evidence of this.
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From her and other experts' understanding of these kinds of
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viruses in general, though, they do think this is the case.
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But there is always a chance that a virus could
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break the rules. And we won't know for sure if
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Zika is that bad boy until we study it fully.
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There are some signs that Zika might not play by
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the rules. In July, genetic material from the Zika virus
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was found in the mucus of a woman's vagina who
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had been infected by Zika. Now, it was found there
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11 days after her symptoms set in. At that point,
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there was no sign of the Zika virus in her
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blood or urine, just the genetic material of Zika in
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her vagina. which raised the possibility that Zika may stick
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around for longer than expected. And because this is all
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so new and when it comes to outbreaks of diseases,
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different experts, depending on their speciality, have different perspectives, we
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also spoke to Cathy Spong, an obstetrician and acting director
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of the National Institute for Child Health and Human Development.
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And we asked her about the CDC's recommendations to wait
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eight weeks after possible exposure to Zika before trying to
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get pregnant.
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If a woman has had Zika, we don't have any
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evidence to say that once that time period has passed,
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that she should have concerns for a future pregnancy. Then again,
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I would say we don't have a lot of data
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on it either.
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Are you.
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happy with the evidence that we have on that at
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the moment to give that?
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This is the best information we have available.
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How confident are you in it?
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It's the best information we have available.
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00:21:10.500 --> 00:21:11.140
Kathy.
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I mean, the CDC has, these are the guidance based
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on the best information we have available.
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Yeah.
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Depending on your perspective on life, you can take the
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unknowns and amplify them in your head or.
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You can underplay them.
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But when it comes to disease, we tend to overplay them.
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So, I mean, there's always unknowns in everything we do.
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And so I think, yes, this is an unknown that
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is a little more, a little heightened in the sense
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that this is something that is new that we don't
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have a lot of data on. That said, it's simply
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one of the many unknowns in pregnancy.
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After the break, Zika has been around for a very
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00:22:02.190 --> 00:22:05.529
long time. So why is it spreading and causing these
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00:22:05.609 --> 00:22:16.670
heartbreaking symptoms now? Hey, it's Wendy from Science Versus, and
424
00:22:16.690 --> 00:22:18.930
I want to tell you about a podcast that I.
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and wonderful world of science, from how concussions affect our
428
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brain to the inner secrets of a snake with a
429
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spider on its tale. It's a lot of news that
430
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you can use and some that you can't, but you're
431
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going to love anyway.
432
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It's hosted by Ira Flato and Flora Lichtman.
433
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Who is an old friend of the show and loves
434
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a pun as much as we do.
435
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Science Friday is on every day wherever you get your podcasts.
436
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Welcome back.
437
00:22:51.279 --> 00:22:55.059
So remember when those scientists first identified Zika in Uganda
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00:22:55.279 --> 00:22:57.490
in 1947 by putting the monkeys up in.
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The tree to get bit by mosquitoes? Well, if we've
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00:23:01.130 --> 00:23:01.950
known about.
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This disease since 1947, a disease that we just heard
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00:23:05.619 --> 00:23:08.619
can do some really scary things to us, especially in
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developing babies, why are we just starting to notice this
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disease now?
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How did we miss it?
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To help us answer this question, we turned to Andrew Haddow,
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00:23:20.490 --> 00:23:23.990
a researcher at the United States Army Medical Research Institute
448
00:23:24.309 --> 00:23:29.710
for Infectious Diseases. Now, Andrew's grandfather just happens to be
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00:23:29.890 --> 00:23:34.640
Alexander Haddow, one of the first scientists to isolate Zika
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back in the 1940s.
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The first time I heard about Zika was probably when
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I was about three or four years old from my
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father during my bedtime stories.
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And before we talk to Andrew about why we underestimated Zika,
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you need to know that he has carried on his
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grandfather's work by making another really big discovery about Zika.
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00:23:57.200 --> 00:24:01.000
a discovery made in the late 2000s in Senegal. And
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00:24:01.039 --> 00:24:04.279
it all started when his buddy Kevin, who's also a scientist,
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00:24:04.839 --> 00:24:07.779
was telling Andrew about this weird illness that he and
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00:24:07.799 --> 00:24:11.509
his mate got when they were working with mosquitoes. I
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00:24:11.529 --> 00:24:12.829
was imagining it was over beer.
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It was. It was over a beer. It was over
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00:24:15.549 --> 00:24:19.769
a beer. Yeah, kind of on a veranda looking out
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over a river. So I said, you know, Kevin, it
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sounds like you have both maybe had Zika virus. We
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need to test your blood. And then he kind of
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leans back in his chair and just says, well, there's
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something else. And I was just like, you know, what else? Because,
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I mean, it's just kind of like, what else could
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there be? And he's like, the other investigator's name was
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Brian Foy. And so he says, well, Brian, Brian's wife
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came down with the same signs and symptoms after he
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got back. And it's just like, what? And I mean,
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all of this together just kind of pointed to the
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likelihood of a sexual transmission event. There were some other
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00:24:58.039 --> 00:25:01.099
signs and symptoms that pointed to the possibility... Like the
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00:25:01.140 --> 00:25:03.119
fact they had sex? I'm sorry?
478
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Like the fact they had sex?
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00:25:04.940 --> 00:25:08.680
Yes. Brian had noticed that there had been blood in
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00:25:08.720 --> 00:25:11.710
his semen and that he had had... His prostate was
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00:25:11.789 --> 00:25:15.769
inflamed and his wife came down with classic... What we
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00:25:15.789 --> 00:25:20.970
would kind of call classic Zika signs and symptoms, fever, rash, etc. So.
483
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Just was kind of one of those things like, wow.
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I mean, I said, yeah, we really have to get your,
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her blood also. We need to, you know, we need
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to test this. And I said, you know, I really
487
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think that it's Zika.
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00:25:35.190 --> 00:25:38.970
Because is this, is this really uncommon for this sort
489
00:25:38.990 --> 00:25:39.859
of virus?
490
00:25:40.170 --> 00:25:45.900
Yes. So before this, this diagnosis, there were no reports,
491
00:25:46.759 --> 00:25:50.680
to my knowledge, of sexual transmission of an arbovirus in
492
00:25:50.700 --> 00:25:55.630
the literature. the closest was a report of Japanese encephalitis
493
00:25:55.670 --> 00:26:00.359
virus in the semen of boars. So this is just
494
00:26:00.420 --> 00:26:05.720
kind of way out there as things go. And so,
495
00:26:06.319 --> 00:26:08.940
you know, it was met with, I think I can say,
496
00:26:09.130 --> 00:26:11.650
a lot of skepticism in our community.
497
00:26:12.089 --> 00:26:15.910
Other studies have recently confirmed what Andrew first discovered, that
498
00:26:15.990 --> 00:26:18.829
Zika can be found in semen, and it stays in
499
00:26:18.890 --> 00:26:22.339
semen longer than it does in blood. In one report,
500
00:26:22.420 --> 00:26:25.740
a woman got infected with Zika through unprotected sex about
501
00:26:25.799 --> 00:26:29.339
a month after her partner showed symptoms of Zika infection.
502
00:26:29.960 --> 00:26:32.740
So that means the virus was alive in her partner's
503
00:26:32.779 --> 00:26:36.380
semen for at least that long. As a result, the
504
00:26:36.400 --> 00:26:40.839
World Health Organization recommends that men who travel to Zika-infected
505
00:26:40.980 --> 00:26:44.900
areas wait six months before having unprotected sex.
506
00:26:46.039 --> 00:26:49.109
Yep, six months. Got it?
507
00:26:50.230 --> 00:26:53.130
Now, Andrew doesn't just probe his mate's sex life for
508
00:26:53.170 --> 00:26:56.289
his research. He's also been studying the genetics of the
509
00:26:56.329 --> 00:26:57.849
Zika virus over time.
510
00:26:58.109 --> 00:26:59.819
So we had a lot of questions for him.
511
00:27:00.650 --> 00:27:04.400
First off, though, why did this outbreak with the microcephaly
512
00:27:04.519 --> 00:27:07.220
and the paralysis happen now?
513
00:27:07.900 --> 00:27:12.160
Maybe the virus could have always done these things, but
514
00:27:12.440 --> 00:27:14.920
first of all, they weren't detected. So I think as
515
00:27:14.960 --> 00:27:17.420
we're seeing more cases, we're just getting a better understanding
516
00:27:17.460 --> 00:27:20.349
of really what the virus is capable of doing. It's
517
00:27:20.410 --> 00:27:22.470
not that it wasn't doing it in the past. It
518
00:27:22.509 --> 00:27:26.490
may literally just be there weren't enough people studied to
519
00:27:26.549 --> 00:27:30.029
really know. The other part is in these areas where
520
00:27:30.089 --> 00:27:34.849
Zika virus is endemic, historically, women or girls would have
521
00:27:35.009 --> 00:27:37.660
likely been infected at a very young age before they
522
00:27:37.740 --> 00:27:41.700
ever even reached puberty. And what that means is they
523
00:27:41.740 --> 00:27:45.079
basically would have been immune when they were adults and
524
00:27:45.119 --> 00:27:48.430
when they were getting pregnant and having children. And that
525
00:27:48.470 --> 00:27:54.480
may also be a reason why we didn't see microcephaly
526
00:27:54.519 --> 00:27:59.119
in those regions before now. Honestly, I think that we
527
00:27:59.220 --> 00:28:03.730
owe a lot to a group of physicians in Brazil
528
00:28:04.210 --> 00:28:09.210
for really pushing the microcephaly, at the time it was
529
00:28:09.250 --> 00:28:14.599
a hypothesis, forward and really bringing widespread attention to this issue.
530
00:28:15.240 --> 00:28:18.650
At first, it was, I'll tell you, it was met
531
00:28:18.690 --> 00:28:22.150
with a lot of skepticism in the scientific community.
532
00:28:22.609 --> 00:28:25.029
Why was there so much skepticism?
533
00:28:26.150 --> 00:28:30.130
Well, I think what happens is we all get tunnel vision. And,
534
00:28:30.150 --> 00:28:33.269
you know, this is what the virus does, and that's
535
00:28:33.329 --> 00:28:35.910
all it does. And it was the same with what
536
00:28:35.950 --> 00:28:39.430
we know now, that the case of sexual transmission, that
537
00:28:39.490 --> 00:28:43.490
was met with skepticism. Then you have Guillain-Barre syndrome, met
538
00:28:43.509 --> 00:28:47.930
with skepticism, and microcephaly. met with skepticism, you know, we
539
00:28:47.990 --> 00:28:52.650
sometimes we get so used to what we would maybe
540
00:28:52.670 --> 00:28:56.109
the norm that we forget that things change and that
541
00:28:56.130 --> 00:28:59.529
we always have to be cognizant that these viruses aren't
542
00:28:59.549 --> 00:29:03.380
an evolutionary arms race and they are trying to adapt
543
00:29:03.779 --> 00:29:07.779
to infect more hosts. So we have to be cognizant
544
00:29:07.900 --> 00:29:10.720
just because something hasn't done anything for, you know, 70
545
00:29:10.720 --> 00:29:13.720
years that doesn't mean that it can't do it in
546
00:29:13.759 --> 00:29:14.220
the future.
547
00:29:14.240 --> 00:29:16.380
Do you think it's possible that the Zika virus is
548
00:29:16.440 --> 00:29:19.160
mutating in some way to make it easier to infect
549
00:29:19.259 --> 00:29:20.220
big populations?
550
00:29:21.200 --> 00:29:23.769
So there's just a lot we don't know about the virus.
551
00:29:23.809 --> 00:29:26.710
We're learning new things almost every week. But what I
552
00:29:26.789 --> 00:29:31.470
can say is it appears that the virus is overall
553
00:29:31.569 --> 00:29:32.369
pretty stable.
554
00:29:32.890 --> 00:29:37.029
So scientists have started tracking how Zika has changed genetically
555
00:29:37.190 --> 00:29:40.319
since it was first detected in 1947. And they have
556
00:29:40.480 --> 00:29:44.799
found minor differences in its genetic code. But so far,
557
00:29:44.880 --> 00:29:47.920
it's still not clear if Zika is evolving to become
558
00:29:48.099 --> 00:29:51.599
more dangerous necessarily, or if it's basically the same old
559
00:29:51.680 --> 00:29:54.480
virus that just happened to find a continent of people
560
00:29:54.539 --> 00:29:59.289
to make sick for the very first time. Okay, so
561
00:29:59.309 --> 00:30:02.349
what have we learnt? First, where did Zika come from?
562
00:30:03.009 --> 00:30:05.849
Researchers first found it in Africa and it's been there
563
00:30:05.930 --> 00:30:09.990
for probably thousands of years. Two, what happens when you
564
00:30:10.009 --> 00:30:13.720
get infected? There's rashes and fevers and while there are
565
00:30:13.759 --> 00:30:18.480
some complications, most of the time the disease is pretty mild.
566
00:30:18.559 --> 00:30:21.940
In fact, 80% of people who get infected don't even
567
00:30:22.039 --> 00:30:26.369
show symptoms. But when you are pregnant, the virus can
568
00:30:26.430 --> 00:30:29.589
make a beeline for the foetus. And we're still trying
569
00:30:29.630 --> 00:30:33.789
to work out the full consequences of this. Third, how
570
00:30:33.849 --> 00:30:36.049
worried should you be if you live or are travelling
571
00:30:36.089 --> 00:30:40.720
to a Zika-affected part of the world? Well, if you're
572
00:30:40.740 --> 00:30:43.039
not pregnant, you're not planning on getting pregnant and you're
573
00:30:43.059 --> 00:30:47.240
not planning on making anyone else pregnant anytime soon, there's
574
00:30:47.299 --> 00:30:50.890
probably no need to be that worried. But if you
575
00:30:51.029 --> 00:30:54.589
are thinking of getting pregnant, this is a real concern.
576
00:30:55.150 --> 00:30:58.450
Because we currently don't know the chance that your baby
577
00:30:58.509 --> 00:31:04.390
will have defects if you are infected. And finally, why
578
00:31:04.470 --> 00:31:08.720
has this new ugly side of Zika reared its head now?
579
00:31:10.119 --> 00:31:11.900
We don't exactly know.
580
00:31:12.299 --> 00:31:14.740
One theory is that people in parts of Africa where
581
00:31:14.759 --> 00:31:17.880
the virus has been around for ages are now immune
582
00:31:17.940 --> 00:31:20.259
to it. And it was only when the virus hit
583
00:31:20.319 --> 00:31:23.740
a large population that has never been exposed before that
584
00:31:23.839 --> 00:31:30.210
trouble struck. So now that we have this problem, the
585
00:31:30.230 --> 00:31:33.779
big question is, of course, how to stop it.
586
00:31:34.480 --> 00:31:36.440
There are a few things that scientists are working on.
587
00:31:36.680 --> 00:31:39.220
They're seeking out a vaccine and they're also trying to
588
00:31:39.279 --> 00:31:47.230
lower mosquito populations, potentially by releasing genetically modified mozzies. Male
589
00:31:47.369 --> 00:31:51.210
mosquitoes have been specifically crafted so that when they bonk
590
00:31:51.470 --> 00:31:56.170
female mosquitoes, the offspring will die young. That is, the
591
00:31:56.210 --> 00:31:58.750
mozzie babies won't be able to make it to adulthood
592
00:31:58.809 --> 00:32:02.720
and won't be able to create more mozzie babies. Theory
593
00:32:02.759 --> 00:32:06.019
goes that if you release enough of these genetically modified
594
00:32:06.259 --> 00:32:10.920
dud mosquitoes, the population of mozzies will drop to hopefully
595
00:32:10.940 --> 00:32:15.009
the point where the diseases won't spread anymore. Small trials
596
00:32:15.069 --> 00:32:18.690
conducted by the company that makes these mosquitoes, Oxitec, found
597
00:32:18.769 --> 00:32:22.250
that releasing these guys could reduce the mozzie population by
598
00:32:22.289 --> 00:32:27.329
around 90%. In August, the FDA approved plans to release
599
00:32:27.390 --> 00:32:30.569
them into Florida, but the community over there will have
600
00:32:30.609 --> 00:32:34.740
to decide whether they want it or not. Thing is,
601
00:32:35.440 --> 00:32:38.519
even if we can get rid of 90% of the mosquitoes,
602
00:32:38.680 --> 00:32:43.279
there are still that cheeky 10% hanging around. Plus, the
603
00:32:43.319 --> 00:32:47.099
virus can spread while we are having sex. So probably
604
00:32:47.200 --> 00:32:49.650
the only way to protect us against Zika in the
605
00:32:49.730 --> 00:32:54.910
long term is to develop a vaccine. As of 2016,
606
00:32:54.910 --> 00:32:58.269
29 different Zika vaccines were in development around the world.
607
00:32:58.529 --> 00:33:00.450
That's according to the World Health Organization.
608
00:33:00.849 --> 00:33:04.579
One trial started in humans back in June, another in August.
609
00:33:04.700 --> 00:33:07.119
But right now, scientists are just checking to see if
610
00:33:07.140 --> 00:33:09.359
the vaccine causes any bad side effects.
611
00:33:09.890 --> 00:33:12.099
That's what happens in the first batch of volunteers.
612
00:33:12.960 --> 00:33:16.119
Even with huge international efforts to make a good vaccine
613
00:33:16.220 --> 00:33:19.839
as soon as possible, the National Institutes of Health estimates
614
00:33:19.960 --> 00:33:26.670
that the earliest date we'll see a vaccine is in 2018. So,
615
00:33:27.569 --> 00:33:30.470
what can you do right now if you live in
616
00:33:30.509 --> 00:33:35.579
an area impacted by Zika? Scientists recommend that you try
617
00:33:35.640 --> 00:33:39.730
to keep mosquitoes away the best way you can. And
618
00:33:39.769 --> 00:33:43.069
that means getting rid of open water in containers or
619
00:33:43.109 --> 00:33:46.809
blocked drains. That's what the mozzies use to breed. Also,
620
00:33:46.890 --> 00:33:49.849
perhaps sleep beneath a net. You can pop on your
621
00:33:49.930 --> 00:33:53.619
air conditioner because mozzies don't like the cold. Also, wear
622
00:33:53.660 --> 00:33:57.779
long sleeves and use bug spray. OK, that's what we
623
00:33:57.819 --> 00:34:01.869
know for now. The research continues... as it always does,
624
00:34:02.230 --> 00:34:07.730
because this is science, and this was Science vs Zika.
625
00:34:12.889 --> 00:34:15.860
This episode has been produced by Diane Wu, Heather Rogers,
626
00:34:15.940 --> 00:34:19.739
Caitlin Kenney, Shruti Ravindran, and our senior producer is Caitlin Sori.
627
00:34:20.440 --> 00:34:23.760
Edited by Annie Rose Strasser and fact-checked by Michelle Harris.
628
00:34:24.320 --> 00:34:27.429
Sound design and music production by Matthew Boll, mixed by
629
00:34:27.510 --> 00:34:29.190
Martin Peralta and Bobby Lord.
630
00:34:29.750 --> 00:34:33.579
Music written by Martin Peralta and Bobby Lord. For key references,
631
00:34:33.719 --> 00:34:34.719
head to our webpage.
632
00:34:35.260 --> 00:34:39.340
Next week, we're tackling forensic science. On CSI, it looks
633
00:34:39.500 --> 00:34:40.139
so easy.
634
00:34:40.639 --> 00:34:41.719
But how much can you.
635
00:34:41.679 --> 00:34:45.210
Really trust the science that gets presented in courtrooms?
636
00:34:45.909 --> 00:34:47.789
I'm Wendy Zuckerman. Back to you next time.