Emerging Drug Resistance in Thailand Threatens Malaria Eradication

The Lancet recently published the results of a longitudinal study examining resistance by malaria parasite to the latest and most effective treatment for the disease, Artemisinin Combination Therapy (ACT) along the Thai-Myanmar border.

Parasite clearance rates increased from a mean half life of 2.7 hours in 2001 to 3.6 hours in 2010, indicating that resistance is growing. Resistance was originally observed on the western side of Cambodia, but has now either spread geographically to western Thailand or emerged on its own. The latter scenario is actually the more frightening possibility. If resistant strains emerge in Sub-Saharan Africa, it could be a major setback.

Though research to develop new drugs is ongoing, ACTs are presently the most effective treatment and a major part of the arsenal with which to stop transmission and prevent early childhood death. Past treatment strategies are now largely ineffective.

Vaccines are also in development (most notably the RTSS vaccine), though I have little confidence that it will be of much use for long. It is a long series of shots and difficult to deliver in areas where medical delivery is poor or non-existent and efficacy is strain and context specific. Malaria vaccines are nice in the popular press, but impractical on the ground.

That resistance is growing in this particular end of the world, is in itself significant. Both regions are notable for poor health delivery, sporadic armed conflicts and marginalized populations. Efforts to contain the spread of resistance are likely futile. Even in the best of times, adequate delivery of care and prevention strategies are near impossible. Displacement of people due to conflict always provide ample opportunities for infectious agents, poor health and death. Tens of thousands of people languish in refugee camps along the border.

The subject of resistance in this region comes up often in meetings of malaria researchers, though I am always struck at the absence of discussion of social factors and conflict and how they create conditions favorable for the spread of resistant pathogens. It is no accident that malaria occurs in the places it does, and no accident that resistant strains of Plasmodium are able to fester and evade efforts to reign it in. It is almost as if the malaria research world believes that genetic adaptation happens at random, which it does not.

Discussion of malaria eradication cannot proceed without discussion of how to eradicate worldwide conflict, entrenched poverty and proper delivery and access to basic health care and the global forces which create these conditions. Yet it does.

Medications, vaccines and preventative interventions cannot work if there is no way to delivery them, and people cannot access them unless there is a local economy with which to support such a system. Malaria research has to address this fundamental issue or we’re just talking in the wind.

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About Pete Larson

Assistant Professor of Epidemiology at the Nagasaki University Institute for Tropical Medicine

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