The key question in front of the world scientists today, after evidence has come in , is on whether the malaria parasites have become immune to the current treatments. If yes, the world is facing its biggest health crisis ever and the challenges for the scientists can be enormous.

In a small community in Western Cambodia, scientists are puzzling over why malaria parasites seem to be developing a resistant to drugs – and fearing the consequences.

Ten days ago, Chhem Bunchhin, a teacher in Battambang Province, became ill with chills, fever, headache and vomiting. At a nearby health centre he was treated with drugs considered a ‘silver bullet’ in the battle against falciparum malaria. This treatment with artesunate drugs was part of a clinical study being carried out by the US Armed Forces Research Institute of Medical Science (AFRIMS).

In the past, artesunates have always cleared malaria parasites from the blood in two or three days. But after four days of monitored treatment, Chhem Bunchhin was still testing positive for parasites. The anti-malarial drugs worked more slowly in Chhem Bunchhin. Dr Delia Bethell, an investigator working on the clinical trials, said he wasn’t alone. Out of about 90 patients included in the study so far, roughly a third to half were still positive for malaria parasites after three days, some even after four or five days.

“It appears that the artesunate is working more slowly than previously,” she said.

“It appears that the parasite probably is developing some kind of tolerance or is somehow less sensitive to the effects of the drug. But nobody knows why that might be.”

These early results need to be more thoroughly investigated, she said.

This has brought into focus the ability of the parasites to evolve resistance and the kind of challenges this could pose for us in terms of health.