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mosquito
Defeating the Curse

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Programme summary

NARRATOR (BILL PATERSON): This is the story of an epic battle between science and nature. A battle to destroy a disease that is one of the biggest killers on the planet, malaria. The stakes could not be higher. Everyday three thousand people, mainly children, die.

Dr MELINDA MOREE (Malaria Vaccine Initiative): It's like loading up seven jumbo jets full of children and ramming them in to the side of Mount Kilimanjaro. That's the number of kids that die everyday from Malaria.

NARRATOR: For a hundred years, science has fought this killer disease, and lost.

Dr STEPHEN HOFFMAN (US Naval Medical Research Institute): The best drug we that we ever had for malaria is almost useless.

NARRATOR: Every time scientists thought they were winning the disease has returned stronger, more virulent, more deadly. But now science is fighting back, its new weapons are the product of bitter cold war rivalries and of modern biotechnology.

Prof NICHOLAS WHITE (Welcome Trust, SE Asia): I think we can roll back malaria, we could, we can eradicate malaria.

NARRATOR: Tonight Horizon investigates, can science finally beat malaria?

NARRATOR: Malaria strikes without warning. It can kill within two days. Every year over a million people die from it. And this global slaughter is due to a single microscopic organism, the malaria parasite. It lives by eating the red blood cells of those it infects. The damaged blood cells then clog blood vessels causing major organ failure, brain damage and death. Throughout history this relentless killer has claimed more lives than any other disease.

Prof NICHOLAS WHITE (Welcome Trust, SE Asia): Malaria is a terrifying disease, it takes over your entire body, brain, your liver, your kidneys your lungs. All these fail and you die. Often in children they may be well one day and they may be dead the next.

NARRATOR: For years the battle against this deadly parasite has been a losing one, but now science is fighting back. Advantages in biotechnology are giving scientists new insights into their enemy. After six years work, in labs in both sides of the Atlantic, they have succeeded in decoding the parasite's DNA, the genes that make it what it is. They have discovered that the parasite has over five hundred genes dedicated to outwitting our immune system. It's a formidable fall, but scientists now believe they have found two new ways to attack the parasite. These new treatments are being tested in Thailand and Mozambique. It could be the start of a new era in our fight against this ancient and deadly disease. The story of science's attempts to defeat malaria began more than a hundred years ago. At this time all scientists knew was that the disease was caused by the malaria parasite. What they didn't know was how the parasite was transmitted from one person to another. For centuries it was believed that malaria was carried by foul smelling air.

Dr CHRIS HENTSCHEL (Medicines for Malaria Venture: The main theory in Europe was that it was a so-called miasma, which was some kind of an evil force that came out of swamps and transmitted itself to, to humans. But it clearly was not a very scientific theory.

NARRATOR: The breakthrough came in 1897, Ronald Ross, a British medical officer working in India, was following a new lead. He believed that mosquitoes might spread the parasite. Malaria experts dismissed the idea as ludicrous. But Ross set out to test the theory, in what would become one of the most important experiments in the history of medicine. He collected mosquitoes and fed them with the blood of people infected with malaria parasites. He wanted to see if it were possible that the parasite could survive inside a cold-blooded insect. He tried many different species of mosquito, but the parasite always died inside them. But when he dissected the anopheles mosquito he saw something no one had seen before. In its gut were malaria parasites. And as he looked closer he saw something amazing. The mosquito not only sucked the parasites in to its gut but this was also where they reproduced. Its offspring were a completely different rod like shape, especially adapted to burrow their way in to the mosquito's salivary gland. This incredible migration completed the parasites lifecycle. They were now ready to be squirted in to the blood of its next human victim.

Dr STEPHEN HOFFMAN (US Naval Medical Research Institute): This was really one of the first examples of, where an understanding of the lifecycle, meaning how a disease is transmitted could actually be applied to preventing that disease.

NARRATOR: Ross's discovery gave the world for the first time a way to fight malaria.

Prof NICHOLAS WHITE: The importance of this was, was tremendous, because it opened up a way of attacking malaria, of controlling malaria, because now we could attack the mosquito. Ross's message to the world was look, if you can control this mosquito, you can control malaria.

NARRATOR: And so an epic battle against the mosquito began. The first attack targeted its breeding grounds, marshes were drained and slow moving rivers were cleared. For the first time in history malaria was in retreat. But these simple measures didn't work everywhere. When the mosquito killers reached the vast jungles and swamps of the tropics they faced a battle on an altogether different scale, mosquitoes were breeding in vast numbers, three hundred and sixty five days of a year. What they needed was a new and far more deadly weapon, and they got it from the US military.

Prof NICHOLAS WHITE: In any tropical theatre of war you lose more soldiers to malaria than you do to bullets. And this ratio can be as much as ten soldiers down to malaria for every one shot. So a tremendous military importance. And that's why the military have been very important in research in to malaria.

NARRATOR: During the second world war the Americans set out to develop a powerful insecticide to kill mosquitoes. They began to test thousands of compounds and eventually they came up with a legend. It destroyed the nervous system of mosquitoes so completely that minute quantities were deadly. Sprayed on to surfaces it was still killing mosquitoes a year later, and it was cheap. Its name was Dichlorodiphenyltrichloroethane, DDT. When the war was over the newly formed World Health Organisation decided to use DDT to launch a bold plan, to eradicate malaria completely. They said malaria would be gone by the 1990s.

Prof NICHOLAS WHITE: This opened up the possibility that we could eradicate malaria. Eradicate malaria from the globe. And this was seriously taken up after the second world war.

NARRATOR: DDT was to consign malaria to the history books by wiping out the mosquitoes that spread the disease. It was a huge undertaking. No corner of the world was to be ignored. No home too humble to receive attention. It was the mosquito's darkest hour. Malaria was on the run.

Dr STEPHEN HOFFMAN: It was dramatically reduced in South America, it was dramatically reduced in India and Sri Lanka where it, where there had been in India eighty million cases prior to eradication, and they were able to reduce it down to fifty thousand cases.

NARRATOR: Victory seemed to be in sight, and malaria was being described as a disease of the past.

NEWS FOOTAGE: Our children will be the first generation free from the enslaving fever.

NARRATOR: But then the mosquito fought back. The weapon it used was evolution. Every day across the world millions upon millions of mosquitoes were being born. With each birth came the chance of a miracle, a mutant that would save the species from extinction.

Prof NICHOLAS WHITE: Because so much DDT was used, and so many mosquitoes were exposed, then a very occasional genetic mutation occurred which allowed one or two mosquitoes to survive the DDT. All the rest died and those few with these genetic mutations survived and there babies spread.

NARRATOR: This new breed of DDT resistant super mosquitoes were unstoppable, they quite literally took over the world. The scientists fought back developing new insecticides, but soon mosquitoes evolved resistance to them too. Before long scientists were locked in an arms race. They needed to develop new insecticides faster than the mosquitoes could evolve resistance to them. But each new chemical turned out to be more expensive than the last. With costs spiralling out of control, the mosquito killers realised they were fighting a losing battle. In 1969, utterly demoralised, the World Health Organisation gave up its war against the mosquito. The worldwide eradication plan was abandoned. After the spraying stopped across the developing world the mosquito returned with a vengeance, and so did malaria.

Dr STEPHEN HOFFMAN: One went from a situation where there were a handful of cases in Sri Lanka and thousands of cases in India to a situation where they went to millions of cases.

NARRATOR: After a twenty five year war against the mosquito the mosquito had won. Scientists would have to think of another way to defeat malaria. In 1979 they started work on the holy grail of malaria research, something that would stop anyone ever catching the disease, a vaccine. Once again the US military led the way. The first attempt used a classic technique, exposing volunteers to a weakened parasite. They took mosquitoes and blasted them with radiation, weakening the parasites inside of them. These weakened parasites wouldn't be strong enough to infect someone with malaria. But they would stimulate the immune system, teaching it to recognise and destroy the parasites. The key was getting the right dose of radiation.

Dr STEPHEN HOFFMAN: If you gave too little radiation to the mosquitoes the parasites weren't weakened enough and you actually infected the people when you exposed them to the mosquitoes. And if you gave too much of radiation the parasites became too weak and they didn't illicit a strong enough immune response to protect against malaria.

NARRATOR: Finally, they got the dose just right, and it seemed to work.

Dr STEPHEN HOFFMAN: The protection that one sees in individuals who are immunised with these irradiated parasites is almost one hundred percent. It lasts for at least nine months, and it works against parasite strains from all over the world.

NARRATOR: But there was one major drawback. This vaccine could not be delivered using a simple injection. Instead the weakened parasites had to be delivered using the bites of over a thousand mosquitoes.

Dr STEPHEN HOFFMAN: This was a completely impractical approach to preventing malaria because it is inconceivable that one could, could get people to be bitten by thousands of infected mosquitoes, which is what it takes, even if one could produce thousands of infected mosquitoes, which one can't do.

NARRATOR: This approach was a dead end. Once more malaria had defeated them. By the early 1980s scientists had failed to control mosquitoes and they had failed to produce a workable vaccine against the parasite. The only hope of controlling the disease now lay with anti-malarial drugs, but science was losing this battle too. The drug that the world had relied on for thirty years was Chloroquin.

Dr CHRIS HENTSCHEL: Chloroquin was in its heyday a very effective drug. It was also safe enough, and above all it was very cheap. And so it really got distributed on a massive scale.

NARRATOR: It was so effective that in the 1950s it was the most commonly taken drug in the world after Aspirin, and it saved millions of lives. But this widespread use of Chloroquin led to its downfall. Again, the problem was evolution, billions upon billions of subtly different parasites were being born every day. It was only a matter of time before a mutant emerged that was unaffected by the drug and produced offspring that were also resistant to it.

Dr STEPHEN HOFFMAN: Unfortunately beginning in Colombia and in Thailand in the late 1950s and early 1960s, resistance to Chloroquin began to develop. Resistance is now spread essentially over the entire globe.

NARRATOR: In a little over twenty years the offspring of just one malaria parasite spread from an area around Thailand across Asia. In 1978 it jumped to the east coast of Africa, and just twelve years later it had taken over the entire continent. Meanwhile in Colombia a separate Chloroquin resistant parasite emerged, it took just ten years to conquer South America. But Chloroquin was just the first of many drugs to fall to resistance.

Dr STEPHEN HOFFMAN: What we have found is that as soon as we develop a new drug, the parasite, this incredibly complex infectious agent, learns how to become resistant to that drug.

NARRATOR: As each drug failed a new one replaced it, and failed even quicker.

Dr ARNOLD BROSSI (World Health Organisation (1978-89)): At the end of the 1970s we got very much worried at the WHO steering committee, that we have no other drugs which could be recommended once resistance had been developed. And we were eagerly looking for something entirely new, something novel.

NARRATOR: By the beginning of the 1980s scientists were desperate for something to beat this parasite. What was needed was a new drug that could attack the parasite in a completely different way. Unbeknownst to most of the world that drug had already been found. It came from China, the trouble was the Chinese hadn't told anybody else it existed. In 1967 Dr Ying Li joined a group of young scientists who had answered the call from the Chinese leader Chairman Mau to solve the problem of malaria. But this would be no ordinary scientific project, because this research was driven by politics.

Prof YING LI (Shanghai Institute of Materia Medica): Even though we were given time to carry out scientific research, we were forced to take time of our work for political meetings and denunciations. We had to constantly read and sing Chairman Mau's thoughts.

NARRATOR: Mau considered everything western to be decadent including medicine. So instead the scientists looked to the Chinese past for inspiration. Ying Li and her team worked their way through two hundred herbs which had traditionally been used against malaria fevers. But none worked. Then they tried a herb called Qing Ha, known in the west as Artemisia. Ying Li and her colleagues followed an ancient recipe two thousand years old for making a kind of tea, that it was claimed could cure malaria. They distilled the tea and added chemicals to refine it until they had isolated the active compound. Then they made a drug called Artemisinin which they tried out on patients dying from malaria, the effect was remarkable.

Prof YING LI: Many of the doctors set by the patients, their sense of joy when they came round was indescribable. We had saved them from the clutches of death itself.

NARRATOR: Artemisinin cleared the blood of malaria parasites quicker than any drug in history. It looked like the Chinese had discovered what the world had been hoping for, a completely new and powerful drug against malaria. It should have been the answer, but communist China was not in the mood for sharing any new discovery with its cold war enemies. It would be another ten years until the word of the new wonder drug filtered out to the rest of the world. Where it was met by disbelief. The west distrusted Chinese science, a science inspired by the ideology of Chairman Mau.

Prof STEVEN MESHNICK (University of North Carolina): What you have to understand is that prior to this a lot of things that had been published in the Chinese literature were just rubbish. For example they had claimed that they had eradicated another tropical disease called schistisomiasis, when in fact they hadn't. There was another claim that they could cure malaria with acupuncture.

NARRATOR: But there was another reason that scientists were sceptical. The molecule of the drug was completely different from any other anti-malarial. So different that western scientists thought it couldn't work.

Dr ARNOLD BROSSI: It's a beautiful molecule to look at, and it caught the attention of many, many people.

NARRATOR: The key to Artemisinin is what chemists call an endoperoxide bridge, two oxygen molecules attach to each other. But usually this is a highly unstable combination.

Dr ARNOLD BROSSI: We never have seen in medicinal chemistry something useful from this type of compound.

Prof STEVEN MESHNICK: It's a compound that could fall apart in exposure to air. And here they were claiming to have a drug that was stable and could be, could be made in to a drug and would last in the body, and the general feeling was this compound couldn't possibly last long enough in the body to have an active effect.

NARRATOR: The only way western scientists were going to believe the Chinese claims was by seeing it for themselves. To do that they needed to get samples of the drug. Once again politics got in the way.

Prof YING LI: The foreigners seemed to be snooping. They were so arrogant and contemptuous. They were astonished that we Chinese had managed to achieve this amazing breakthrough when they had spent so much time and effort on it and failed.

Dr ARNOLD BROSSI: They basically didn't trust us, they thought we would like to exploit this new drug and bring it to the market in the western world.

NARRATOR: And there seemed good reason for the Chinese to be suspicious.

Prof STEVEN MESHNICK: Many of the members of the WHO steering committee that was responsible for anti-malarial drug development were members of the US military. The reason for this was that the US military has had a long and very productive history in anti-malarial drug development.

Dr ARNOLD BROSSI: It was certainly not very helpful to have American presentation on the steering board of the Word Health Organisation on malaria. And especially since some of them showed up in uniform which made very obvious where they were coming from. This didn't help in getting information we wanted to have on this exciting new drug.

NARRATOR: The Chinese refused to release the plant or the drug to the rest of the world. Fifteen years after its discovery the drug was still unavailable to millions who needed it.

Prof STEVEN MESHNICK: It was very frustrating in the 1980s because here was a promising compound that many people wanted to work on but yet we couldn't get it. It wasn't being sent out of China. So it became clear that we needed another source for the compound. And in order to have another source for the compound we had to find the plant somewhere outside of China. And this led to an effort by the US military to find the plant growing somewhere.

NARRATOR: If Artemisinin really was a new miracle malaria cure then the US military were going to make sure they had it too. They looked in scores of countries across the world, until they stumbled across it growing along the banks of a river, the Potomac river that runs through the heart of Washington DC.

Prof STEVEN MESHNICK: They initially found Artemisinin on the banks of the Potomac, but soon they were finding it everywhere, it was just a weed that grew in, in people's gardens.

NARRATOR: With their own supply of plants the Americans could now find out if the Chinese claims for the drugs were true. It took another ten years. But scientists not only confirmed the Chinese results, they also came up with a theory as to how Artemisinin worked. It was all to do with the unstable endoperoxide bridge.

Prof STEVEN MESHNICK: Artemisinin is like a bomb, and there's a trigger to this bomb, and the trigger turns out to be that endoperoxide bridge, those two oxygens. When those two oxygens come in contact with iron they fall apart and the whole molecule explodes.

NARRATOR: The malaria parasite is rich in iron which it gets from the red blood cells it feeds on. This iron sets off the endoperoxide trigger, destroying the parasite in the process. Scientists were now convinced that they had what they were looking for, a highly effective and completely new anti-malarial drug. After thirty years of secrecy and cold war politics they were ready to give the world a new weapon to fight malaria, it was desperately needed. By the late 1990s every other drug had failed and malaria was running riot. Artemisinin was the last hope. Could a drug based on an ancient Chinese herbal remedy really defeat malaria? Northern Thailand, the place where the malaria parasite first developed resistance, not just to Chloroquin but to a string of other anti-malarial drugs. This is the front line in science's battle with malaria. This clinic was set up to study anti-malarial treatments. It is currently testing the effectiveness of Artemisinin based drugs. The malaria cases that are seen here are perhaps the toughest test for any new drug.

Dr LIZ ASHLEY (Shoklo Malaria Research Unit): This border area of Thailand is a big problem area for malaria, particularly it harbours some of the most drug resistant malaria in the world. Most of our patients are coming over the border from Burma and they pick malaria up during the course of their work in forested areas.

NARRATOR: Dr Liz Ashley is supervising the trials, every day people flood in to the clinic with suspected malaria. This eleven year old boy, Tang Pong, is typical. He has a high fever and has been vomiting for three days, he's also suffering from severe headaches. A blood sample is taken and confirms that he has the disease. He lives in an area where multi-drug resistant malaria is rife. The old malaria drugs would be useless against these parasites. So he's given his first dose of Artemisinin. After an hours observation he's sent home to rest. The next morning he returns to the clinic. It is immediately obvious that the Artemisinin has worked.

Dr LIZ ASHLEY: The main thing is that his fever's gone. I think he's feeling better, he's starting to ease a little bit so, so things have improved from yesterday certainly.

NARRATOR: He must receive a further two doses to make sure that all the malaria parasites have been cleared from his body. But his recovery is not in doubt. His case is not unique, trials here and elsewhere in the world have all shown that Artemisinin is incredibly effective.

Dr LIZ ASHLEY: I can give you a figure, a ninety five percent cure for the people that we try them on, they're also pleasant to take and people get a resolution of their symptoms very, very quickly.

NARRATOR: And even better, since monitoring of Artemisinin first began several years ago, not a single case of resistance has been detected. Artemisinin seems to be a drug with real staying power. Last year, over thirty years after its discovery by the Chinese, Artemisinin became the basis of the World Health Organisation's fight against malaria. Finally it seems there is an effective anti-malarial drug that can be used anywhere in the world. There is just one problem, there isn't enough of it.

Dr CHRIS HENTSCHEL: No drug is perfect, this particular drug relies on a natural product, and that's quite a complicated process to produce, it's quite complicated to scale up.

NARRATOR: To make Artemisinin you need the Artemisia plant, and that means growing it. From planting the Artemisia seed to producing the drug takes eighteen months, the drug then has a shelf life of only two years. The World Health Organisation estimates that over a hundred forty million courses of Artemisinin based drugs are needed to treat malaria this year alone. And that figure will double by 2006. But last year, fewer than seven million courses were produced. Millions will suffer and many will die from a disease that is easily cured with this drug if only they could get it. What's desperately needed is a drug with the same qualities as Artemisinin but one that doesn't depend on the supply of a plant. Five years ago, in Omaha Nebraska, one man had already started working on a solution. A synthetic, or manmade version of Artemisinin. That could be produced in a simple chemical process and in vast quantities.

Prof JONATHAN VENNERSTROM (University of Nebraska): Our aim was to come up with a synthetic replacement for the Artemisinins. Something that would be cheaper to manufacture but would have the same anti-malarial properties.

NARRATOR: To kill malaria parasites this new drug would also need the crucial endoperoxide bridge.

Prof JONATHAN VENNERSTROM: Well we knew early on that the engine if you will of Artemisinin is the endoperoxide bridge. And this is an unstable bond chemically but it is absolutely necessary for the anti-malarial activity of Artemisinin.

NARRATOR: The challenge was to design a molecule that would protect this explosive chemical bond, making it stable enough to survive in the body until it met the parasite. So Vennerstrom chose to build his molecule around the most stable carbon based structure known, adamantine.

Prof JONATHAN VENNERSTROM: If this is the engine of the molecule we need to have a firm mounting. So this is what provided that necessary strength, this part called the adamantine. So this way it could kill the parasite but still have the necessary stability to stay together long enough to get to the parasite.

NARRATOR: The process used was called Ozonoloscence, and because of this the resulting compounds were called Oz. Vennerstrom produced several variants of the Oz molecule, each with a subtly different chemical composition. After just three attempts he'd created a near perfect drug, Oz 3. Tests in the lab showed that it killed malaria parasites more effectively than Artemisinin itself. There was just one problem, to be cheap and effective this drug would have to be a pill. A pill that dissolves in water and is absorbed by the stomach. But Oz 3 was an oil that did not dissolve in water. The solution should have been simple, Vennerstrom redesigned the molecule adding chemicals that made it dissolve in water, but this wasn't the answer.

Prof JONATHAN VENNERSTROM: Although we had achieved better water solubility we had lost the anti-malarial activity. So we had to keep going back to the drawing board time and time again before we really worked this out.

NARRATOR: Vennerstrom was caught in a trap. Every time he tried to make the molecule dissolve in water it lost its anti-malarial properties. And every molecule which killed malaria didn't dissolve in water.

Solving this paradox took another two and a half years and two hundred and seventy seven attempts. But when they finished they had a drug that dissolved in water and could be produced in vast quantities. And it also seemed to be highly effective at killing malaria parasites in the lab. But would this synthetic version of Artemisinin work as well as the original? The obvious place to test it was Thailand, home to some of the most resistant malaria strains on the planet. In January 2005 the first batch of this new drug arrived in Bangkok. It was the start of a major six month trial to test out its effectiveness. This is the first patient to take part in the trial. He contracted malaria in a remote border region, but has been brought to Bangkok where his condition and the effectiveness of the drug can be closely monitored. It's too early in the trial to tell if Oz 277 will be the answer, but hopes are high.

Dr CHRIS HENTSCHEL: The immediate hope for this drug of course is to show it's safe and effective in clinical trials. But beyond that we hope it can be produced on a huge scale, very cheaply, and that it can become a major weapon in the fight against malaria.

NARRATOR: If the trials are a success then it will mean that there will finally be enough a Artemisinin based drugs to take on malaria around the world. The shortages will be over. But scientists know that even if the trials are a success this is not the end of the story. One day the parasite could develop resistance even to Artemisinin based drugs.

Dr RIPLEY BALLOU (GlaxoSmithKline Biologicals): The malaria parasite has an uncanny ability to develop resistance to virtually every drug that has been thrown against it. And the few that we have, have a limited life span.

NARRATOR: Artemisinin has bought scientists time, it has given them a breathing space to work on new approaches to defeat malaria. And so they have returned to the dream that has always eluded them, a vaccine.

Dr RIPLEY BALLOU: In virtually every infectious disease for which there is a vaccine, vaccination has shown itself to be the most cost effective way of disease control. And it would, if it's true for the rest of the infectious diseases it's going to be true for malaria as well.

NARRATOR: All previous attempts of a malaria vaccine have ended in failure. And some believe the parasite is so sophisticated that a vaccine will never be possible. But now Ripley Ballou and his team are trying a new approach. Using the latest biotechnology they set out to try and discover the key to the parasites success. They realise that its greatest weapon was its incredible ability to evade the human immune system. And as they looked closer they found that its surface was covered in a special protein that acted as a kind of camouflage. This surface protein meant the immune system failed to recognise the parasite as an intruder, leaving it free to do its deadly work.

Dr RIPLEY BALLOU: So the protein on the surface of the parasite actually works as a decoy to the immune system. And that's been part of the key to solving the problem.

NARRATOR: It was a crucial breakthrough, because it opened up an entirely new approach. Instead of creating a vaccine against the whole parasite, they made one that targeted just the surface protein. To see whether it worked they used themselves as guinea pigs.

Dr RIPLEY BALLOU: We took mosquitoes, infected them with malaria and let them bite us. And to see if we would in fact develop malaria. And there were about eight of us in the group that volunteered to do this. I unfortunately was not protected and did develop malaria but one of my good friends, one of my colleagues, was completely protected from malaria. And that was, as they say, the talking bear, it was a fantastic observation that in fact this could be done.

NARRATOR: Although the principle had been proven the vaccine was far from perfect. In seven of the volunteers it had failed to provide any protection. They realised they had to find a better way of targeting the surface protein. Eventually they came up with an ingenious solution.

Dr RIPLEY BALLOU: Well after a lot of trial and error we came upon the idea of hooking the malaria protein to another protein that we knew in itself was a good vaccine.

NARRATOR: This new vaccine would combine the malaria surface protein with another protein that the immune system would recognise. This would re-programme the body's immune system to treat the malaria protein as an infection. When the body next saw the surface protein on the parasite it would now recognise it. The immune system would now be alerted to the presence of the parasite and destroy it. When they tried it in the lab it seemed to work. So they decided to put it to the test. Last year a full scale trial of this vaccine was carried out in Mozambique. The aim was to test the vaccine in those who were most at risk from malaria, children.

Dr MELINDA MOREE (Malaria Vaccine Initiative): In Mozambique one in five children doesn't live to see their fifth birthday. Malaria's the number one killer. So while there are hundreds of millions of cases of malaria around the world in people who suffer from that, death predominantly ninety percent of the deaths happen in kids under five. So what we're really looking to do is not necessarily with our first vaccine to wipe out malaria, but really to stop these kids from getting so sick and dying.

NARRATOR: Over a period of six months the vaccinated children were checked to see who had developed malaria. The results were reported in the press as a triumph. But a look behind the headlines showed a more complicated picture. In fact only thirty percent of the children were completely protected from getting malaria. The results were better when it came to the most severe life threatening forms of the disease. Here the protection was nearly sixty percent. So whilst the vaccine wasn't very good at stopping children catching malaria, it was much more effective at stopping the disease progressing in to a form that might kill them.

Dr MELINDA MOREE: So that to us while may be not perfection was really significant. Because you think about that, that means over half the kids would have had severe malaria didn't have it, and that's a pretty significant finding.

NARRATOR: A vaccine that gives full protection against malaria is still some way off, but it's no longer seen as impossible. More than a dozen teams around the world are now chasing this great prize.

Dr MELINDA MOREE: Does that mean we have a vaccine today? No. But it means that we're absolutely sure that it is possible, we just need to figure out the timing part of it.

NARRATOR: In the mean time Artemisinin, the Chinese wonder drug born of cold war politics holds out the promise of a cheap effective cure. For the first time in a generation science has delivered an effective weapon to once again declare war on malaria. It's a war that many scientists now believe we can win.

Prof NICHOLAS WHITE: Yes we can eradicate malaria, its' not going to be easy but it can be done and we have the tools now to do that, and we should use them.

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