STEVE INSKEEP, HOST:
Malaria drugs are failing at an alarming rate. It's happening in Southeast Asia, where drug-resistant strains of malaria emerge. Researchers have published two new reports in the medical journal The Lancet. So what if this drug resistance spreads?
NPR's Jason Beaubien reports.
JASON BEAUBIEN, BYLINE: Global health officials get nervous when they see new strains of drug-resistant malaria developing in Southeast Asia because it's a dreaded pattern that they've seen before.
ARJEN DONDORP: Somehow antimalarial drug resistance always starts in that part of the world, especially western Cambodia is notorious.
BEAUBIEN: Arjen Dondorp leads malaria research at the Mahidol Oxford Tropical Medicine Research Unit in Bangkok.
DONDORP: In the past, chloroquine resistance originated there. Sulfadoxine-pyrimethamine, the next generation of very good antimalarial - resistance to that originated there.
BEAUBIEN: And now resistance to artemisinin-based drugs has erupted there. These are the drugs that are currently the World Health Organization's recommended treatment for the majority of malaria cases. These drugs have been credited with helping to bring global malaria deaths down to an all-time low. But now malaria parasites are becoming immune to them.
Dondorp was in the midst of a study comparing the conventional, first-line artemisinin drugs in the greater Mekong region to a new generation of antimalarials. And it was in the middle of that study that he and his colleagues saw the dramatic rise in drug resistance.
DONDORP: We noticed incredible high failure rates with the first-line treatment.
BEAUBIEN: The overall failure rate was 50%. But in some places, the drugs weren't working nine times out of 10. Dondorp says the resistance was even worse than they'd expected.
DONDORP: We knew already it was in Cambodia, but it had increased dramatically over the years. And what was new, that it was also present in northeastern Thailand and southern Vietnam.
BEAUBIEN: Health officials in Cambodia were aware that the drugs were failing and had switched back to an older medicine. Now Vietnam and Thailand are also moving away from the WHO's recommended first-line malaria treatment. Shunmay Yeung is an associate professor at the London School of Hygiene and Tropical Medicine who studies malaria and malaria drug resistance.
SHUNMAY YEUNG: It is really worrying. I mean, there's been massive success, really. In the last 15 years, we've halved the number of deaths due to malaria globally.
BEAUBIEN: That's also due to an increased use of bed nets and other efforts. But Yeung stresses that the artemisinin-based antimalarials have been, in her words, wonderfully effective drugs.
YEUNG: You know, three days' treatment and you're better. So they're really great drugs. So it's really worrying. If this emerged or spread to Africa, it would be a disaster.
BEAUBIEN: That's because the majority of malaria cases globally are in Africa. So far, the drug-resistant mutations haven't turned up in Africa, but the fear is that they could. Yeung says there are new antimalarials in the development pipeline. But if drug resistance spreads quickly, patients would have to rely, at least temporarily, on older, potentially less effective medicines. And that could be a major setback to global progress against the disease.
Jason Beaubien, NPR News.
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