The world’s number-one treatment for malaria is on the brink of failure because of a new strain of drug-resistant parasites — unless health policymakers take action. Professor Sir Nicholas White says that the mosquito-borne parasite responsible for severe malaria is now showing resistance to the prime treatment, Artemisinin Combination Therapy (ACT), across South-East Asia. If this resistance jumps to Africa, he warns, the tragedy will be on a massive scale.