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The story that I'm going
to tell you today,
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for me, began back in 2006.
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That was when I first heard
about an outbreak of mysterious illness
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that was happening in the Amazon
rainforest of Peru.
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The people that were getting sick
from this illness,
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they had horrifying symptoms, nightmarish.
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They had unbelievable headaches,
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they couldn't eat or drink.
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Some of them were even hallucinating --
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confused and aggressive.
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The most tragic part of all
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was that many of the victims
were children.
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And of all of those that got sick,
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none survived.
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It turned out that what was killing
people was a virus,
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but it wasn't Ebola, it wasn't Zika,
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it wasn't even some new virus
never-before-seen by science.
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These people were dying
of an ancient killer,
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one that we've known about for centuries.
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They were dying of rabies.
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And what all of them had in common
was that as they slept,
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they'd all been bitten by the only mammal
that lives exclusively on a diet of blood:
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the vampire bat.
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These sorts of outbreaks
that jump from bats into people,
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they've become more and more common
in the last couple of decades.
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In 2003, it was SARS.
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It showed up in Chinese animal markets
and spread globally.
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That virus, like the one from Peru,
was eventually traced back to bats,
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which have probably harbored it,
undetected, for centuries.
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Then, 10 years later, we see Ebola
showing up in West Africa.
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and that surprised just about everybody,
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because according
to the science at the time,
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Ebola wasn't really supposed
to be in West Africa.
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That ended up causing the largest
and most widespread Ebola outbreak
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in history.
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So there's a disturbing trend here, right?
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Deadly viruses are appearing in places
where we can't really expect them,
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and as a global health community,
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we're caught on our heels.
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We're constantly chasing
after the next viral emergency
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in this perpetual cycle,
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always trying to extinguish epidemics
after they've already started.
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So with new diseases appearing every year,
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now is really the time
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that we need to start thinking
about what we can do about it.
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If we just wait for the next
Ebola to happen,
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we might not be so lucky next time.
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We might face a different virus,
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one that's more deadly,
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one that spreads better among people,
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or maybe one that just completely
outwits our vaccines,
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leaving us defenseless.
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So can we anticipate pandemics?
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Can we stop them?
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Those are really hard questions to answer,
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and the reason is that the pandemics --
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the ones that spread globally,
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the ones that we really
want to anticipate --
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they're actually really rare events.
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And for us as a species
that is a good thing --
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that's why we're all here.
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But from a scientific standpoint,
it's a little bit of a problem.
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That's because if something
happens just once or twice,
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that's really not enough
to find any patterns.
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Patterns that could tell us when
or where the next pandemic might strike.
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So what do we do?
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Well, I think one of the solutions
we may have is to study some viruses
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that routinely jump from wild
animals into people,
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or into our pets, or our livestock,
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even if they're not the same viruses
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that we think are going
to cause pandemics.
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If we can use
those everyday killer viruses
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to work out some of the patterns
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of what drives that initial, crucial jump
from one species to the next,
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and, potentially, how we might stop it,
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then we're going to end up better prepared
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for those viruses that jump
between species more rarely
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but pose a greater threat of pandemics.
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Now, rabies, as terrible as it is,
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turns out to be a pretty nice
virus in this case.
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You see, rabies is a scary, deadly virus.
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it has 100 percent fatality.
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That means if you get infected with rabies
and you don't get treated early,
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there's nothing that can be done.
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There is no cure.
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You will die.
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And rabies is not just
a problem of the past either.
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Even today, rabies still kills
50 to 60,000 people every year.
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Just put that number in some perspective.
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Imagine the whole West African
Ebola outbreak --
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about two-and-a-half years;
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you condense all the people
that died in that outbreak
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into just a single year.
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That's pretty bad.
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But then, you multiply it by four,
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and that's what happens
with rabies every single year.
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So what sets rabies apart
from a virus like Ebola
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is that when people get it,
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they tend not to spread it onward.
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That means that every single time
a person gets rabies,
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it's because they were bitten
by a rabid animal,
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and usually, that's a dog or a bat.
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But it also means that those jumps
between species,
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which are so important to understand,
but so rare, for most viruses,
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for rabies, they're actually
happening by the thousands.
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So in a way, rabies
is almost like the fruit fly
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or the lab mouse of deadly viruses.
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This is a virus that we can use
and study to find patterns
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and potentially test out new solutions.
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And so, when I first heard
about that outbreak of rabies
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in the Peruvian Amazon,
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it struck me as something
potentially powerful,
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because this was a virus that was jumping
from bats into other animals
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often enough that we might
be able to anticipate it ...
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Maybe even stop it.
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So as a first-year graduate student
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with a vague memory
of my high school Spanish class,
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I jumped onto a plane
and flew off to Peru,
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looking for vampire bats.
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And the first couple of years
of this project were really tough.
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I had no shortage of ambitious plans
to rid Latin America of rabies,
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but at the same time,
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there seemed to be an equally endless
supply of mudslides and flat tires,
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power outages, stomach bugs
all stopping me.
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But that was kind of par for the course,
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working in South America,
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and to me, it was part of the adventure.
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But what kept me going
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was the knowledge that for the first time,
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the work that I was doing
might actually have some real impact
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on people's lives in the short term.
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And that struck me the most
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when we actually went out to the Amazon
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and were trying to catch vampire bats.
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You see, all we had to do was show up
at a village and ask around.
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"Who's been getting bitten
by a bat lately?"
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And people raised their hands,
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because in these communities,
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getting bitten by a bat
is an everyday occurrence,
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happens every day.
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And so all we had to do
was go to the right house,
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open up a net
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and show up at night,
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and wait until the bats tried
to fly in and feed on human blood.
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So to me, seeing a child with a bite wound
on his head or blood stains on his sheets,
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that was more than enough motivation
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to get past whatever logistical
or physical headache
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I happened to be feeling on that day.
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Since we were working
all night long, though,
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I had plenty of time to think about
how I might actually solve this problem,
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and it stood out to me
that there were two burning questions.
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The first was that we know
that people are bitten all the time,
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but rabies outbreaks
aren't happening all the time --
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every couple of years,
maybe even every decade,
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you get a rabies outbreak.
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So if we could somehow anticipate
when and where the next outbreak would be,
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that would be a real opportunity,
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meaning we could vaccinate
people ahead of time,
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before anybody starts dying.
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But the other side of that coin
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is that vaccination
is really just a Band-Aid.
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It's kind of a strategy of damage control.
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Of course it's lifesaving and important
and we have to do it,
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but at the end of the day,
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no matter how many cows,
how many people we vaccinate,
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we're still going to have exactly the same
amount of rabies up there in the bats.
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The actual risk of getting bitten
hasn't changed at all.
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So my second question was this:
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could we somehow
cut the virus off at its source?
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If we could somehow reduce the amount
of rabies in the bats themselves,
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then that would be a real game changer.
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We've been talking about shifting
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from a strategy of damage control
to one based on prevention.
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So, how do we begin to do that?
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Well, the first thing
we needed to understand
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was how this virus actually works
in its natural host --
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in the bats.
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And that is a tall order
for any infectious disease,
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particularly one in a reclusive
species like bats,
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but we had to start somewhere.
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So the way we started
was looking at some historical data.
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When and where had these outbreaks
happened in the past?
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And it became clear
that rabies was a virus
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that just had to be on the move.
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It couldn't sit still.
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The virus might circulate in one area
for a year, maybe two,
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but unless it found a new group of bats
to infect somewhere else,
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it was pretty much bound to go extinct.
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So with that, we solved one key part
of the rabies transmission challenge.
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We knew we were dealing
with a virus on the move,
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but we still couldn't say
where it was going.
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Essentially, what I wanted was
more of a Google Maps-style prediction,
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which is, "What's
the destination of the virus?
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What's the route it's going
to take to get there?
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How fast will it move?"
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To do that, I turned
to the genomes of rabies.
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You see, rabies, like many other viruses,
has a tiny little genome,
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but one that evolves
really, really quickly.
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So quickly that by the time the virus
has moved from one point to the next,
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it's going to have picked up
a couple of new mutations.
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And so all we have to do
is kind of connect the dots
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across an evolutionary tree,
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and that's going to tell us
where the virus has been in the past
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and how it spread across the landscape.
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So, I went out and I collected cow brains,
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because that's where
you get rabies viruses.
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And from genome sequences that we got
from the viruses in those cow brains,
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I was able to work out
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that this is a virus that spreads
between 10 and 20 miles each year.
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OK, so that means we do now have
the speed limit of the virus,
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but still missing that other key part
of where is it going in the first place.
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For that, I needed to think
a little bit more like a bat,
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because rabies is a virus --
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it doesn't move by itself,
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it has to be moved around by its bat host,
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so I needed to think about
how far to fly and how often to fly.
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My imagination didn't get me
all that far with this
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and neither did little digital trackers
that we first tried putting on bats.
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We just couldn't get
the information we needed.
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So instead, we turned
to the mating patterns of bats.
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We could look at certain parts
of the bat genome,
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and they were telling us that some
groups of bats were mating with each other
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and others were more isolated.
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And the virus was basically following
the trail laid out by the bat genomes.
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Yet one of those trails stood out
as being a little bit surprising --
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hard to believe.
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That was one that seemed to cross
straight over the Peruvian Andes,
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crossing from the Amazon
to the Pacific coast,
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and that was kind of hard to believe,
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as I said,
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because the Andes are really tall --
about 22,000 feet,
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and that's way too high
for a vampire to fly.
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Yet --
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(Laughter)
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when we looked more closely,
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we saw, in the northern part of Peru,
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a network of valley systems
that was not quite too tall
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for the bats on either side
to be mating with each other.
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And we looked a little bit more closely --
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sure enough, there's rabies
spreading through those valleys,
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just about 10 miles each year.
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Basically, exactly as our evolutionary
models had predicated it would be.
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What I didn't tell you
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is that that's actually
kind of an important thing
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because rabies had never been seen before
on the western slopes of the Andes,
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or on the whole Pacific coast
of South America,
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so we were actually witnessing,
in real time, a historical first invasion
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into a pretty big part of South America,
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which raises the key question:
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"What are we going to do about that?"
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Well, the obvious short-term
thing we can do is tell people:
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you need to vaccinate yourselves,
vaccinate your animals;
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rabies is coming.
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But in the longer term,
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it would be even more powerful
if we could use that new information
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to stop the virus
from arriving altogether.
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Of course, we can't just tell bats,
"Don't fly today,"
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but maybe we could stop the virus
from hitching a ride along with the bat.
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And that brings us to the key lesson
that we have learned
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from rabies-management programs
all around the world,
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whether it's dogs, foxes,
skunks, raccoons,
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North America, Africa, Europe.
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It's that vaccinating the animal source
is the only thing that stops rabies.
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So, can we vaccinate bats?
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You hear about vaccinating dogs
and cats all the time,
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but you don't hear too much
about vaccinating bats.
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It might sound like a crazy question,
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but the good news is that we actually
already have edible rabies vaccines
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that are specially designed for bats.
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And what's even better
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is that these vaccines
can actually spread from bat to bat.
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All you have to do is smear it on one
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and let the bats' habit
of grooming each other
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take care of the rest of the work for you.
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So that means, at the very least,
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we don't have to be out there vaccinating
millions of bats one by one
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with tiny little syringes.
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(Laughter)
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But just because we have that tool
doesn't mean we know how to use it.
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Now we have a whole laundry
list of questions.
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How many bats do we need to vaccinate?
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What time of the year
do we need to be vaccinating?
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How many times a year
do we need to be vaccinating?
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All of these are questions
that are really fundamental
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to rolling out any sort
of vaccination campaign,
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but they're questions
that we can't answer in the laboratory.
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So instead, we're taking
a slightly more colorful approach.
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We're using real wild bats,
but fake vaccines.
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We use edible gels that make bat hair glow
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and UV powders that spread between
bats when they bump into each other,
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and that's letting us study
how well a real vaccine might spread
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in these wild colonies of bats.
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We're still in the earliest
phases of this work,
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but our results so far
are incredibly encouraging.
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They're suggesting that using
the vaccines that we already have,
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we could potentially drastically reduce
the size of rabies outbreaks.
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And that matters, because as you remember,
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rabies is a virus that always
has to be on the move,
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and so every time we reduce
the size of an outbreak,
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we're also reducing the chance
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that the virus makes it
onto the next colony.
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We're breaking a link
in the chain of transmission.
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And so every time we do that,
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we're bringing the virus
one step closer to extinction.
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And so the thought, for me,
of a world in the not-too-distant future
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where we're actually talking
about getting rid of rabies altogether,
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that is incredibly
encouraging and exciting.
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So let me return to the original question.
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Can we prevent pandemics?
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Well, there is no silver-bullet
solution to this problem,
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but my experiences with rabies
have left me pretty optimistic about it.
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I think we're not too far from a future
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where we're going to have genomics
to forecast outbreaks
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and we're going to have clever,
new technologies
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like edible, self-spreading vaccines
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that can get rid of these
viruses at their source
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before they have a chance
to jump into people.
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So when it comes to fighting pandemics,
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the holy grail is just to get
one step ahead.
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And if you ask me,
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I think one of the ways
that we can do that
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is using some of the problems
that we already have now,
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like rabies --
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sort of the way an astronaut
might use a flight simulator,
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figuring out what works and what doesn't,
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and building up our tool set
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so that when the stakes are high,
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we're not flying blind.
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Thank you.
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(Applause)