PASSENGERS travelling by air to Africa from South East Asia and South America should be screened for malaria to prevent the spread of drug-resistant strains of the disease, British scientists suggested yesterday.

New research has shown that a version of the parasite that is immune to two frontline treatments arose in Asia and then spread to Africa, probably carried by people travelling by air.

The introduction of the resistant Plasmodium falciparum strain to Africa has made both the inexpensive drugs used to treat the disease, chloroquine and sulfadoxine pyrimethamine (SP), largely ineffective in the region where malaria poses the greatest danger.

To prevent a repeat of this experience, public health officials need to take steps to stop people who are carrying drug-resistant parasites, from travelling to Africa.

The call comes the day after the Medicines for Malaria Venture announced promising results from a new anti-malarial drug that could transform the fight against the disease. OZ, a synthetic cousin of a traditional Chinese herbal medicine, is to begin clinical trials next year after trials with computer and animal models suggested that it would be highly effective.

In a study published today in the journal Science, researchers from the London School of Hygiene and Tropical Medicine traced the genetic origins of four mutations in the Plasmodium falciparum organism that make it immune to chloroquine and SP to South East Asia.

Malaria kills about one million people every year and infects up to 500 million. It is the second most deadly infection after Aids.