The development of a vaccine against malaria looks to have come a step closer. Research carried out at the St Radboud University Medical Centre in Nijmegen has shown how easy it is to offer people complete protection against a malaria infection.

The researchers chose to adopt a new strategy to fight malaria, by testing whether it's possible to make people immune to the disease more quickly – and that seems to have been proven.

Every year millions of people suffer the consequences of malaria, especially children who haven't built up sufficient resistance against the disease. The majority of the victims live in Africa.

Breakthrough
Malaria is spread by the mosquito, that places the malaria parasite into the human bloodstream. Volunteers who had never had malaria, and possessed no immunity to the disease, were stung several times by the mosquito, while simultaneously being given the well-known anti-malaria medicine chloroquine. They developed an immune reaction and were not sick. A few months later they were stung again, without the protection of chloroquine. The built-up immunity provided sufficient protection, says research professor Robert Sauerwein from the Medical Parasitology section at the St Radboud University Medical Centre in Nijmegen.

According to the researchers, the secret lies in a specific group of defensive cells, the co-called multifunctional T-cells, which make hostile proteins harmless. An unusual aspect of the Nijmegen approach is that volunteers are 'vaccinated' with the whole parasite in place of the unhealthy protein. The ultimate goal is to use a mild parasite to create immunity, in the same way that a mild flu virus is used for a flu vaccine.

Effective
In particular, the speed with which the resistance seemed to be built up in the Nijmegen experiment is a major breakthrough, according to Professor Sauwerwein:

"What we have done is used a malaria parasite to immunise people. We’ve done that the conventional way with mosquito stings. So it’s also important to say that we still haven’t found a malaria vaccine, but certainly a new method that produces malaria immunity a lot faster."

Immunity
The research emulated the natural circumstances in which people become infected and build up immunity. In total, the volunteers were stung 45 times over a period of three months. Professor Sauerwein says that in the tropics people are sometimes stung one hundred times a night by mosquitoes, and thus they develop their immunity, but it takes five to ten years.

Some volunteers experienced for themselves what others would consider to be normal. One volunteer who was stung by a mosquito without the protection of chloroquine developed real malaria, but Professor Sauerwein says that after treatment she recovered without complications.

Lame parasite
According to parasitologist Dr Petra Mens from the Biomedical Research Centre of the Royal Institute for the Tropics, the discovery is a step forward. The big challenge now lies in the development of a vaccine that offers long-lasting protection. The current research doesn’t extend beyond one month after infection.
 

"So that means you really only have one month’s guaranteed protection. The question now is naturally how long this protection will last, because in Africa people are continuously infected by mosquitos. And if a new vaccination must be given, for example, every six months, that' s not really realistic. Certainly not in huge regions like Africa, Southeast Asia and South America."

According to Dr Mens, the research is not only helping scientists in Europe, but also the people around the world who catch malaria every year, resulting in a million deaths and 30 million sick. The Nijmegen research can' t help them yet, but researcher Professor Sauerwein says that the vaccine has come a step closer:

"What we must do now is stop using the mosquito as a natural injection, but we want to have the parasite in a needle so that it can be administered by injection. We're already in contact with an American company that has the necessary technology. And the other thing is that we don’t want to use chloroquine any more to weaken the malaria parasite, because in Africa there’s a lot of resistance towards that medicine, so we want to weaken the malaria parasite by another method. That could be, for example, by making it lame through genetic manipulation or through radiation treatment."

Resistance
According to Professor Sauerwein, an injection with a weakened parasite works just as effectively as a mosquito sting under the protection of an anti-malaria medicine. The vaccine offers a way out of the growing problem that people have become resistant to particular anti-malaria medicines. Under normal circumstances, the parasite disappears from the body after three days. In Africa, chloroquine is not prescribed any more as a medicine, because the parasites have also become resistant to it. A more resistant variant can always emerge while the vaccine is teaching the body to combat the disease.