Researchers developing a vaccine against malaria have published results showing a high success rate in early stage clinical trials.
The scientists at an American biotech company irradiated mosquitoes to weaken the malaria-causing parasites they carry. The parasites were then injected into humans to trigger an immune response.
Researchers found the vaccine, which is being developed in the US, protected 12 out of 15 patients from the disease, when given in high doses. The research is published in the journal Science.
Lead author Dr Robert Seder, from the Vaccine Research Center at the National Institutes of Health, in Maryland, said scientists were excited by the result."But it is important that we repeat it, extend it and do it in larger numbers," he said.
It has been known for several decades that exposure to mosquitoes treated with radiation can protect against malaria, the BBC reports.
However, studies have shown that it takes more than 1,000 bites from the insects over time to build up a high level of immunity, making it an impractical method of widespread protection.
Instead, US biotech company Sanaria has taken lab-grown mosquitoes, irradiated them and then extracted the malaria-causing parasite (Plasmodium falciparum), all under the sterile conditions.
These living but weakened parasites are then counted and placed in vials, where they can then be injected directly into a patient's bloodstream.
A group of 57 volunteers took part in the vaccine trial. Researchers found that for participants not given any vaccine, and those given low doses, almost all became infected with malaria. For the small group given the highest dosage, only three of 15 patients became infected after exposure to malaria.