Artemisin resistance: is disaster looming for key antimalarial?

26 May 2009

Paul Chinnock

Source: Bloomberg (see original article)

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The antimalarial drug artemisinin – used in the form of artemisinin combination therapy (ACT) – is now the recommended treatment for malaria, replacing older drugs to which the malaria parasite is now resistant. At present there are no other drugs for malaria in the development “pipeline”.

But the appearance of resistance to artemisinin in Southeast Asia (see previous report on TropIKA.net) has been described by malaria specialists as a “disaster”. They speak of a “doom scenario” in which artemisinin-resistant strains of the parasite develop throughout the malaria-endemic world, including Africa where most malaria cases and deaths occur.

A report from Cambodia and Thailand, published on Bloomberg Press, features an interview with Arjen Dondorp of the Wellcome Trust-Mahidol University Oxford Tropical Medicine Research Programme, based in Bangkok. He says a flood of counterfeit pills from China and elsewhere is helping to breed artemisinin resistance. This development threatens to unleash a global malaria disaster and undo the decades of work required to develop ACT. In Dr Dondorp’s view the present situation is a “time bomb”.

Doom

WHO has yet to launch the Gates Foundation-funded initiative it plans in Cambodia and Thailand to combat the spread of resistance – see the earlier TropIKA.net story. It is hoped that work will begin in June. Dr Dondorp speaks of a “doom scenario” if the action taken is not successful. This would involve migrant workers carrying the bug throughout Thailand, and on to Myanmar and India. Later the strain would spread to Africa.

“If we lose the artemisinins at this stage, just now when we dare to mention the word ‘eradication’ again, it would be a disaster for malaria control. It would cause millions of deaths, without exaggeration” said Dr Dondorp, lead author of an as yet unpublished study which demonstrates the extent of artemisinin resistance in the Pailin area of Cambodia, close to the Thai border.

Charles Delacollette, head of WHO’s Mekong Malaria Programme, which covers Cambodia, Laos, Myanmar, Thailand, Vietnam and part of China said, however, that the doom scenario may be a decade away from materializing, giving the world time to prevent it.

Fighting the fakes

Resistance to earlier antimalarials also seems to have first begun in Cambodia but the massive scale of substandard and fake products now entering the country increases the likelihood that artemisinin-resistant strains will develop and spread. Some of the counterfeits contain low doses of artemisinin and many are artemisinin monotherapy products. Both promote the development of resistance. (Artemisinin should only be used in combination with an older antimalarial as this reduces the possibility that resistance will appear.)

The efforts of the local health system and WHO to prevent the appearance of Dr Dondorp’s doom scenario must be accompanied by law enforcement to interrupt the supply of fake drugs.