The World Health Organisation has warned that improper use of the malaria drug artemisinin could allow the parasite responsible to become resistant to the treatment, as has been the case with all earlier medicines for the illness.

Concerns are growing that the best weapon against the disease may be rendered useless if doctors in poorer countries continue to use it as a sole agent to fight the disease, rather than as part of the more expensive combination therapy, which is known to be a 95% effective cure.

Using artemisinin as a monotherapy not only means that the disease is not being fought effectively, but it also gives the malaria parasite a good chance of building up resistance to the drug. And this situation is being made even worse by the fact that many manufacturers, mainly from China, India and Vietnam, are instructing that artemisinin should be taken for just five days, but this dose is no where near enough to combat the illness.

“It is critical that artemisinin be used correctly,” Dr Lee Jong-wook, WHO’s Director-General, said in a statement. “We request pharmaceutical companies to immediately stop marketing single-drug artemisinin tablets and instead market artemisinin combination therapies only. The new treatment guidelines we are releasing today provide countries with clear and evidence-based direction on the best treatment options for malaria.”

And driving home the potential seriousness of the situation, Dr Arata Kochi, newly-appointed director of WHO's malaria department, remarked: “If we lose ACTs, we’ll no longer have a cure for malaria…and it will probably be at least ten years before a new one can be discovered.”

Malaria affects around half a billion people and claims more than 1 million lives worldwide every year, but the death toll will rise dramatically if the only available cure is lost.