Without drugs your chances of surviving severe malaria are nil. With drugs you should make it but, worryingly, even many medicines are losing their effectiveness.
“Drug resistance is a major threat. We know from history that every time we think we have outsmarted malaria, we learn the humbling lesson that we are dealing with a very wily parasite,” says Dr Robert Newman, director of the World Health Organization’s (WHO) global malaria programme.
However, on 25 April 2012, World Malaria Day, there were many things to celebrate. Deaths from malaria had fallen more than 25 per cent over the last decade. For the first time ever, a malaria vaccine had reached the final stage of clinical trials. There were also a number of promising new weapons being developed to fight mosquitoes, ranging from lasers that zap the bugs mid-flight, to fungi that disable the malaria parasite.
“We have an incredible opportunity ahead of us,” says Robert Newman. “Through universal coverage with current methods, and with the new tools in development, we can save millions of lives in the near term, and may be able to eradicate malaria in the next 40 years.”
A Global problem
Today, around half of the world’s population are at risk of malaria, with sub-Saharan Africa being one of the worst affected regions. Over half a million people die from malaria each year, and more than two million become ill. ‘Airport malaria’ – malaria transmitted by stowaway mosquitoes — is expected to become more of a problem as global temperatures rise.
The tiny, single-celled parasite is a master of disguise. By altering the proteins on its surface, Plasmodium is able to change its appearance regularly to avoid being recognized by our immune system. And its 5,000 genes are constantly mutating, developing resistance to all the drugs we throw at it. As a result, malaria was once considered too hard to beat.
But now two groups of researchers are getting tantalizingly close to producing a vaccine. The first of these vaccines is based on a strange phenomenon that was discovered in the 1970s. Researchers noticed that if mosquitoes were exposed to a blast of radiation, it damaged the DNA of Plasmodium in the mosquitoes’ salivary glands. “People who were bitten by these irradiated mosquitoes developed immunity to malaria,” explains Dr Stephen Hoffman, chief executive of Sanaria, a biotech company dedicated to creating a malaria vaccine.
For the last decade, Stephen Hoffman has been trying to mimic this effect and create a vaccine, using Plasmodium extracted from the salivary juice of irradiated mosquitoes. The company started in Hoffman’s kitchen, but these days it has labs and US headquarters in Rockville, Maryland, and a team of highly-skilled staff — all proficient at dissecting mosquito saliva glands. “One person can dissect around 100 in one hour,” says Hoffman.
Results from its first clinical trial last year, in which 80 human volunteers were injected with the irradiated Plasmodium, were disappointing: just over five per cent of people achieved immunity. But a follow-up study in mice and monkeys resulted in over 70 per cent immunity, when it was injected directly into a vein. So Hoffman’s team is now conducting another clinical trial in humans, administering the vaccine intravenously.
Meanwhile, over at the GlaxoSmithKline labs in Belgium, Joe Cohen and his team are very close to producing a malaria vaccine too. Their potion, called Mosquirix, contains a fragment of Plasmodium from its blood-surfing stage inside the human body. When given the vaccine, our bodies learn to recognise the disguise worn by the parasite when it first enters, allowing us to arm our immune system ready to attack when the real thing arrives. “It only takes 30 minutes for Plasmodium to travel to the liver, so the body’s defences have to act very quickly,” says Dr Allan Pamba, a member of Cohen’s team.
“We are thrilled by these results – this vaccine could save hundreds of thousands of lives every year,” says Pamba.
A vaccine that confers 50 per cent immunity still leaves a lot of people vulnerable, however, and effective treatment would require more than just drugs. Currently, for example, malaria is often misdiagnosed because the initial symptoms are similar to a really bad case of the flu: fever, chills, headache, sickness and muscle pain.
Mobilising treatment
But if you’re infected by the most deadly species of the parasite -Plasmodium falciparum – the disease can progress exceedingly rapidly, causing death within days. Diagnosing and treating malaria swiftly is clearly key to saving lives -and one tool that could help tackle the disease is the humble mobile phone.
Until now, many countries have used a paper-based system to track their medical supplies. In countries such as Tanzania, in East Africa, this has meant that around 40 per cent of clinics were out of malaria diagnosis kits and medicine at any one time, with new supplies sometimes taking months to arrive.
Modern gadgets could overcome this problem. A pilot programme in Tanzania (backed by IBM, Novartis and Vodafone) is thought to have saved hundreds of lives in just a few months last year, thanks to text messages, Google Maps and cloud computing software to track inventories of life-saving medications at remote clinics. It ensures that supplies are restocked before they run low. Such technological innovations, along with novel ways to tackle mosquitoes and new vaccines, will improve the lives of millions.
Speaking at the Malaria Forum in October 2011, Bill Gates said, “Eventually, with relentless focus, we can eradicate malaria. We’ve already shrunk the malaria map considerably. We can make it disappear.” Excitingly, it looks like he could be right.
How to stop transmission of the malaria parasite
GENETIC MODIFICATION
One way of stopping malaria is to help mosquitoes fight off the Plasmodium parasite. This is exactly what George Dimopoulos, from John Hopkins University in Maryland, is trying to do.
Malaria is carried by over 40 different species of mosquito, however, and genetically engineering every species isn’t feasible. Instead, the researchers aim to use the GM insect in regions where there’s only one predominant species of malaria-carrying mosquito.
NOSE BLOCKING
Filippo Mancia from Columbia University and Vanessa Ruta from the Rockefeller University, both in New York, are using X-ray crystallography to reveal the atomic structure of the odour receptors on a mosquito’s antenna. After mapping out the exact shape and structure of the odour receptor, the scientists will then use Bayer CropScience’s database to search for chemicals with a mirror-image shape. These molecular mimics can latch onto the odour receptors, blocking the mosquito’s ‘nose’.
The end result will be the world’s most effective insect repellent. “Ultimately we should be able to develop something that will prevent any insect bite, which could be used to tackle not just malaria, but all insect-borne diseases,” says Dr Mancia.
KILLER FUNGUS
Mosquitoes are vulnerable to some types of fungus. Now researchers are taking advantage of this to genetically engineer a special fungus, designed to grab onto mosquitoes and block the exit route for Plasmodium falciparum – the most deadly form of the malaria parasite.
In lab-based tests, Plasmodium was nearly completely eradicated from the saliva glands of mosquitoes dosed with the fungus. The researchers are now arranging permits to set up field trials in Burkina Faso, West Africa. They plan to construct giant domes covered in fungus-impregnated net, with the aim of creating a malaria-free zone inside the dome. As well as protecting humans, it could also protect livestock.
ZAP ‘EM WITH LASERS
If all else fails, we could resort to frying mosquitoes using laser beams. Intellectual Ventures, the company belonging to Nathan Myhrvold, Microsoft’s former chief technology officer, has already made a prototype – cobbled together from parts found in printers, digital cameras and projectors.
Luckily the laser software is sophisticated enough to recognise its prey before shooting, preventing it from cooking butterflies, for example. It can even differentiate between male and female mosquitoes, ensuring that only the malaria-carrying females are killed. Myhrvold envisages using the laser to create protective ‘fences’ around people’s houses, doctor’s clinics, or perhaps even agricultural fields. They estimate that such a device could cost as little as USD 50.