TEDxMaastricht
Bart Knols: 3 new ways to kill mosquitoes
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We can use a mosquito's own instincts against her. In a rather unforgettable presentation, Bart Knols demos the imaginative solutions his team is developing to fight malaria -- including Limburger cheese and a deadly pill.
Bart Knols - Malariologist
Bart Knols is a doctor committed to killing mosquitoes and ending malaria. Full bio
Bart Knols is a doctor committed to killing mosquitoes and ending malaria. Full bio
Double-click the English transcript below to play the video.
00:16
(Mosquito buzzing)
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(Swat)
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Gotcha.
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Mosquitos. I hate them.
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Don't you?
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That awful buzzing sound at night around your ears
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that drives you absolutely crazy?
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Knowing that she wants to stick a needle in your skin
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and suck out your blood? That's awful, right?
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In fact, there's only one good thing I can think of
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when it gets to mosquitos.
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When they fly into our bedroom at night,
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they prefer to bite my wife.
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But that's fascinating, right?
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Why does she receive more bites than I do?
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And the answer is smell, the smell of her body.
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And since we all smell different and produce chemicals
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on our skin that either attract or repel mosquitos,
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some of us are just more attractive than others.
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So my wife smells nicer than I do, or I just
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stink more than she does.
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Either way, mosquitos find us in the dark
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by sniffing us out. They smell us.
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And during my Ph.D, I wanted to know exactly
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what chemicals from our skin mosquitos used,
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African malarial mosquitos use to track us down at night.
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And there's a whole range of compounds that they do use.
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And this was not going to be an easy task.
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And therefore, we set up various experiments.
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Why did we set up these experiments?
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Because half the world's population runs the risk
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of contracting a killer disease like malaria
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through a simple mosquito bite.
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Every 30 seconds, somewhere on this planet,
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a child dies of malaria, and Paul Levy this morning,
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he was talking about the metaphor of the 727 crashing into the United States.
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Well, in Africa, we have the equivalent of seven jumbo 747s
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crashing every day.
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But perhaps if we can attract these mosquitos to traps,
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bait it with our smell, we may be able to stop transmission
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of disease.
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Now solving this puzzle was not an easy thing,
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because we produce hundreds of different chemicals on the skin,
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but we undertook some remarkable experiments
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that managed us to resolve this puzzle very quickly indeed.
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First, we observed that not all mosquito species
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bite on the same part of the body. Strange.
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So we set up an experiment
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whereby we put a naked volunteer in a large cage,
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and in that cage we released mosquitos
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to see where they were biting on the body of that person.
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And we found some remarkable differences.
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On the left here you see the bites
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by the Dutch malarial mosquito on this person.
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They had a very strong preference for biting on the face.
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In contrast, the African malarial mosquito
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had a very strong preference for biting the ankles and feet of this person,
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and that of course we should have known all along
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because they're called mosqui-toes, you see? (Laughter)
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That's right. (Applause)
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And so we started focusing on the smell of feet,
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on the smell of human feet,
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until we came across a remarkable statement in the literature
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that said that cheese smells after feet
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rather than the reverse. Think of it.
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And this triggered us to do a remarkable experiment.
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We tried, with a tiny little piece of Limburger cheese,
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which smells badly after feet,
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to attract African malaria mosquitos.
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And you know what? It worked.
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In fact, it worked so well that now we have a synthetic mixture
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of the aroma of Limburger cheese that we're using in Tanzania
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and has been shown there to be two to three times
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more attractive to mosquitos than humans.
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Limburg, be proud of your cheese,
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as it is now used in the fight against malaria.
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(Applause)
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That's the cheese, just to show you.
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My second story is remarkable as well.
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It's about man's best friend. It's about dogs.
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And I will show you
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how we can use dogs in the fight against malaria.
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One of the best ways of killing mosquitos
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is not to wait until they fly around like adults
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and bite people and transmit disease.
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It's to kill them when they're still in the water as larvae.
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Why? Because they are just like the CIA.
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In that pool of water, these larvae are concentrated.
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They're all together there. They are immobile.
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They can't escape from that water. They can't fly.
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And they're accessible. You can actually walk up
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to that pool and you can kill them there, right?
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So the problem that we face with this is that,
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throughout the landscape, all these pools of water
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with the larvae, they are scattered all over the place,
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which makes it very hard for an inspector like this
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to actually find all these breeding sites and treat them with insecticides.
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And last year we thought very, very hard,
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how can we resolve this problem? Until we realized
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that just like us, we have a unique smell,
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that mosquito larvae also have a very unique smell.
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And so we set up another crazy experiment,
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because we collected the smell of these larvae,
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put it on pieces of cloth, and then did something very remarkable.
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Here we have a bar with four holes,
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and we put the smell of these larvae in the left hole.
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Ooh, that was very quick.
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And then you see the dog. It's called Tweed. It's a border collie.
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He's examining these holes, and now he's got it already.
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He's going back to check the control holes again,
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but he's coming back to the first one,
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and now he's locking into that smell,
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which means that now we can use dogs
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with these inspectors to much better find
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the breeding sites of mosquitos in the field,
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and therefore have a much bigger impact on malaria.
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This lady is Ellen van der Zweep. She's one of the best dog-trainers in the world,
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and she believes that we can do a lot more.
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Since we also know that people that carry malaria parasites
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smell different compared to people that are uninfected,
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she's convinced that we can train dogs
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to find people that carry the parasite.
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That means that in a population where malaria
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has gone down all the way, and there's few people remaining with parasites,
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that the dogs can find these people,
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we can treat them with anti-malarial drugs, and give the final blow to malaria.
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Man's best friend in the fight against malaria.
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My third story is perhaps even more remarkable,
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and, I should say, has never been shown to the public until today.
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Yeah.
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It's a crazy story, but I believe it's perhaps the best
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and ultimate revenge against mosquitos ever.
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In fact, people have told me that now they will enjoy
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being bitten by mosquitos.
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And the question of course is, what would make someone
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enjoy being bitten by mosquitos?
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And the answer
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I have right here in my pocket,
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if I get it.
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It's a tablet, a simple tablet,
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and when I take it with water,
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it does miracles.
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Thank you.
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(Drinking)
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Now let me show you how this works.
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Here in this box I have a cage
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with several hundred hungry
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female mosquitos
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that I'm just about to release. (Laughter)
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Just kidding, just kidding.
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What I'm going to show you is I'm gonna stick my arm into it
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and I will show you how quickly they will bite.
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Here we go.
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Don't worry, I do this all the time in the lab.
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There we go. Okay.
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Now, on the video, on the video here,
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I'm going to show you exactly the same thing,
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except that what I'm showing you on the video
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happened one hour after I took the tablet.
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Have a look. That doesn't work. Okay. Sorry about that.
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I'm sticking in my arm, I'm giving them a big juicy
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blood meal, I'm shaking them off, and we follow them through time
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to see these mosquitos get very, very sick indeed,
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here shown in fast motion,
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and three hours later what we see at the bottom
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of the cage is dead mosquitos,
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very dead mosquitos, and I'm going to say, ladies and gentlemen,
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we have swapped the cards with mosquitos.
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They don't kill us. We kill them.
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(Applause)
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Now — (Laughter) —
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Maastricht, be prepared.
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Now think of what we can do with this.
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We can actually use this to contain outbreaks
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of mosquito-born diseases, of epidemics, right?
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And better still, imagine what would happen if,
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in a very large area, everyone would take these drugs,
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this drug, for just three weeks.
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That would give us an opportunity to actually eliminate
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malaria as a disease.
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So cheese, dogs and a pill to kill mosquitos.
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That's the kind of out-of-the-box science that I love doing,
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for the betterment of mankind,
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but especially for her, so that she can grow up
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in a world without malaria. Thank you. (Applause)
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ABOUT THE SPEAKER
Bart Knols - MalariologistBart Knols is a doctor committed to killing mosquitoes and ending malaria.
Why you should listen
Bart Knols is a malariologist with eleven years of experience managing large-scale research programs in East and Southern Africa. He’s worked at the United Nations (IAEA), served as a consultant for the World Health Organization, and acted as a Board Member of the UBS Bank Optimus Foundation in Switzerland. He has published over 140 peer-reviewed research articles and received the Ig Nobel Prize and an IAEA Special Service Award in 2006 and became a laureate of the Eijkman medal in 2007. He is currently the Managing Director at In2Care BV, Science Director & Managing Partner at Soper Strategies, and serves as Chair of the Advisory Board of the Dutch Malaria Foundation.
Bart Knols | Speaker | TED.com