Hadyn Parry: Re-engineering mosquitos to fight disease

95,695 views ・ 2013-01-03

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Translator: Joseph Geni Reviewer: Morton Bast
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So I'd like to start by focusing on
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the world's most dangerous animal.
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Now, when you talk about dangerous animals,
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most people might think of lions or tigers or sharks.
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But of course the most dangerous animal
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is the mosquito.
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The mosquito has killed more humans
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than any other creature in human history.
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In fact, probably adding them all together,
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the mosquito has killed more humans.
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And the mosquito has killed more humans than wars
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and plague.
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And you would think, would you not,
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that with all our science, with all our advances in society,
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with better towns, better civilizations, better sanitation,
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wealth, that we would get better at controlling mosquitos,
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and hence reduce this disease.
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And that's not really the case.
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If it was the case, we wouldn't have
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between 200 and 300 million cases of malaria every year,
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and we wouldn't have
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a million and a half deaths from malaria,
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and we wouldn't have a disease
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that was relatively unknown 50 years ago
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now suddenly turned into
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the largest mosquito-borne virus threat that we have,
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and that's called dengue fever.
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So 50 years ago, pretty much no one had heard of it,
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no one certainly in the European environment.
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But dengue fever now, according to the World Health Organization,
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infects between 50 and 100 million people every year,
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so that's equivalent to the whole of the population
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of the U.K. being infected every year.
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Other estimates put that number at roughly double
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that number of infections.
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And dengue fever has grown in speed quite phenomenally.
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In the last 50 years, the incidence of dengue
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has grown thirtyfold.
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Now let me tell you a little bit about what dengue fever is,
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for those who don't know.
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Now let's assume you go on holiday.
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Let's assume you go to the Caribbean,
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or you might go to Mexico. You might go to Latin America,
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Asia, Africa, anywhere in Saudi Arabia.
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You might go to India, the Far East.
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It doesn't really matter. It's the same mosquito,
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and it's the same disease. You're at risk.
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And let's assume you're bitten by a mosquito
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that's carrying that virus.
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Well, you could develop flu-like symptoms.
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They could be quite mild.
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You could develop nausea, headache,
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your muscles could feel like they're contracting,
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and you could actually feel like your bones are breaking.
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And that's the nickname given to this disease.
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It's called breakbone fever,
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because that's how you can feel.
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Now the odd thing is, is that once you've been bitten
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by this mosquito, and you've had this disease,
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your body develops antibodies,
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so if you're bitten again with that strain,
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it doesn't affect you.
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But it's not one virus, it's four,
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and the same protection that gives you the antibodies
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and protects you from the same virus that you had before
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actually makes you much more susceptible to the other three.
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So the next time you get dengue fever,
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if it's a different strain, you're more susceptible,
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you're likely to get worse symptoms,
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and you're more likely to get the more severe forms,
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hemorrhagic fever or shock syndrome.
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So you don't want dengue once,
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and you certainly don't want it again.
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So why is it spreading so fast?
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And the answer is this thing.
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This is Aedes aegypti.
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Now this is a mosquito that came, like its name suggests,
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out of North Africa, and it's spread round the world.
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Now, in fact, a single mosquito will only travel
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about 200 yards in its entire life. They don't travel very far.
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What they're very good at doing is hitchhiking,
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particularly the eggs.
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They will lay their eggs in clear water, any pool, any puddle,
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any birdbath, any flower pot,
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anywhere there's clear water, they'll lay their eggs,
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and if that clear water is near freight, it's near a port,
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if it's anywhere near transport,
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those eggs will then get transported around the world.
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And that's what's happened. Mankind has transported
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these eggs all the way around the world,
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and these insects have infested over 100 countries,
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and there's now 2.5 billion people living in countries
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where this mosquito resides.
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To give you just a couple of examples
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how fast this has happened,
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in the mid-'70s, Brazil declared, "We have no Aedes aegypti,"
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and currently they spend about a billion dollars now
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a year trying to get rid of it, trying to control it,
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just one species of mosquito.
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Two days ago, or yesterday, I can't remember which,
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I saw a Reuters report that said
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Madeira had had their first cases of dengue,
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about 52 cases, with about 400 probable cases.
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That's two days ago.
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Interestingly, Madeira first got the insect in 2005,
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and here we are, a few years later,
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first cases of dengue.
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So the one thing you'll find is that where the mosquito goes,
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dengue will follow.
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Once you've got the mosquito in your area,
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anyone coming into that area with dengue,
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mosquito will bite them, mosquito will bite somewhere else,
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somewhere else, somewhere else,
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and you'll get an epidemic.
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So we must be good at killing mosquitos.
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I mean, that can't be very difficult.
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Well, there's two principle ways.
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The first way is that you use larvicides.
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You use chemicals. You put them into water where they breed.
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Now in an urban environment, that's extraordinarily difficult.
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You've got to get your chemical into every puddle,
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every birdbath, every tree trunk.
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It's just not practical.
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The second way you can do it
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is actually trying to kill the insects as they fly around.
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This is a picture of fogging.
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Here what someone is doing
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is mixing up chemical in a smoke
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and basically spreading that through the environment.
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You could do the same with a space spray.
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This is really unpleasant stuff,
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and if it was any good, we wouldn't have this massive increase
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in mosquitos and we wouldn't have this massive increase in dengue fever.
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So it's not very effective, but it's probably
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the best thing we've got at the moment.
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Having said that, actually, your best form of protection
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and my best form of protection is a long-sleeve shirt
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and a little bit of DEET to go with it.
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So let's start again. Let's design a product,
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right from the word go, and decide what we want.
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Well we clearly need something that is effective
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at reducing the mosquito population.
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There's no point in just killing the odd mosquito here and there.
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We want something that gets that population right the way down
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so it can't get the disease transmission.
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Clearly the product you've got has got to be safe to humans.
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We are going to use it in and around humans.
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It has to be safe.
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We don't want to have a lasting impact on the environment.
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We don't want to do anything that you can't undo.
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Maybe a better product comes along in 20, 30 years.
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Fine. We don't want a lasting environmental impact.
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We want something that's relatively cheap, or cost-effective,
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because there's an awful lot of countries involved,
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and some of them are emerging markets,
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some of them emerging countries, low-income.
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And finally, you want something that's species-specific.
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You want to get rid of this mosquito that spreads dengue,
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but you don't really want to get all the other insects.
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Some are quite beneficial. Some are important to your ecosystem.
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This one's not. It's invaded you.
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But you don't want to get all of the insects.
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You just want to get this one.
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And most of the time, you'll find this insect
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lives in and around your home,
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so this -- whatever we do has got to get to that insect.
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It's got to get into people's houses, into the bedrooms,
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into the kitchens.
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Now there are two features of mosquito biology
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that really help us in this project,
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and that is, firstly, males don't bite.
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It's only the female mosquito that will actually bite you.
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The male can't bite you, won't bite you,
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doesn't have the mouth parts to bite you.
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It's just the female.
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And the second is a phenomenon
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that males are very, very good at finding females.
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If there's a male mosquito that you release,
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and if there's a female around, that male will find the female.
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So basically, we've used those two factors.
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So here's a typical situation,
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male meets female, lots of offspring.
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A single female will lay about
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up to 100 eggs at a time,
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up to about 500 in her lifetime.
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Now if that male is carrying a gene
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which causes the death of the offspring,
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then the offspring don't survive,
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and instead of having 500 mosquitos running around,
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you have none.
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And if you can put more, I'll call them sterile,
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that the offspring will actually die at different stages,
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but I'll call them sterile for now.
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If you put more sterile males out into the environment,
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then the females are more likely to find a sterile male
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than a fertile one, and you will bring that population down.
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So the males will go out, they'll look for females,
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they'll mate. If they mate successfully, then no offspring.
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If they don't find a female, then they'll die anyway.
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They only live a few days.
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And that's exactly where we are.
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So this is technology that was developed
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in Oxford University a few years ago.
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The company itself, Oxitec, we've been working
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for the last 10 years, very much on a sort of similar
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development pathway that you'd get with a pharmaceutical company.
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So about 10 years of internal evaluation, testing,
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to get this to a state where we think it's actually ready.
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And then we've gone out into the big outdoors,
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always with local community consent,
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always with the necessary permits.
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So we've done field trials now in the Cayman Islands,
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a small one in Malaysia,
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and two more now in Brazil.
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And what's the result?
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Well, the result has been very good.
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In about four months of release,
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we've brought that population of mosquitos
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— in most cases we're dealing with villages here
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of about 2,000, 3,000 people, that sort of size,
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starting small —
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we've taken that mosquito population down
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by about 85 percent in about four months.
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And in fact, the numbers after that get,
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those get very difficult to count, because there just aren't any left.
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So that's been what we've seen in Cayman,
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it's been what we've seen in Brazil
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in those trials.
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And now what we're doing is we're going through a process
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to scale up to a town of about 50,000,
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so we can see this work at big scale.
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And we've got a production unit in Oxford,
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or just south of Oxford, where we actually produce these mosquitos.
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We can produce them,
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in a space a bit more than this red carpet,
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I can produce about 20 million a week.
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We can transport them around the world.
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It's not very expensive, because it's a coffee cup --
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something the size of a coffee cup
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will hold about three million eggs.
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So freight costs aren't our biggest problem. (Laughter)
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So we've got that. You could call it a mosquito factory.
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And for Brazil, where we've been doing some trials,
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the Brazilian government themselves have now built
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their own mosquito factory, far bigger than ours,
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and we'll use that for scaling up in Brazil.
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There you are. We've sent mosquito eggs.
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We've separated the males from the females.
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The males have been put in little pots
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and the truck is going down the road
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and they are releasing males as they go.
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It's actually a little bit more precise than that.
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You want to release them so that
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you get good coverage of your area.
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So you take a Google Map, you divide it up,
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work out how far they can fly,
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and make sure you're releasing such that you get
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coverage of the area, and then you go back,
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and within a very short space of time,
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you're bringing that population right the way down.
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We've also done this in agriculture.
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We've got several different species of agriculture coming along,
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and I'm hoping that soon
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we'll be able to get some funding together so we can get back
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and start looking at malaria.
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So that's where we stand at the moment,
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and I've just got a few final thoughts,
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which is that this is another way in which biology
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is now coming in to supplement chemistry
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in some of our societal advances in this area,
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and these biological approaches are coming in
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in very different forms,
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and when you think about genetic engineering,
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we've now got enzymes for industrial processing,
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enzymes, genetically engineered enzymes in food.
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We have G.M. crops, we have pharmaceuticals,
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we have new vaccines,
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all using roughly the same technology, but with very different outcomes.
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And I'm in favor, actually. Of course I am.
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I'm in favor of particularly where the older technologies
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don't work well or have become unacceptable.
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And although the techniques are similar,
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the outcomes are very, very different,
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and if you take our approach, for example,
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and you compare it to, say, G.M. crops,
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both techniques are trying to produce a massive benefit.
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Both have a side benefit,
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which is that we reduce pesticide use tremendously.
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13:27
But whereas a G.M. crop is trying to protect the plant,
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for example, and give it an advantage,
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what we're actually doing is taking the mosquito
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and giving it the biggest disadvantage it can possibly have,
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rendering it unable to reproduce effectively.
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So for the mosquito, it's a dead end.
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Thank you very much. (Applause)
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