New York Times Examines Drug-Resistant Malaria Along Thai-Cambodian Border

The New York Times on Tuesday examined recent research indicating that Plasmodium falciparum malaria parasites near Cambodia's border with Thailand have shown signs of resistance to artemisinin-based combination therapies. According to the Times, although the studies found "relatively early signs of resistance" to artemisinin, researchers have expressed concern that the drug-resistant strain could spread worldwide, particularly because the Thai-Cambodian border has been a "starting point" for the spread of other drug-resistant malaria strains.

For one study, published in December 2008 in the New England Journal of Medicine, researchers found that artemisinin failed to treat malaria among two patients but that those patients eventually were treated successfully. However, the recent studies also found that artemisinin can take up to 120 hours to clear parasites from the bloodstream, compared with 48 hours a few years ago. Mark Fukuda, U.S. Army physician and a co-author of the December study, said the research demonstrates "that therapy for some patients fails" because "the malaria goes away and comes back."

Although the December study used treatments that contained only artemisinin, health officials typically recommend that physicians prescribe combination therapies that contain other malaria treatments that remain in the bloodstream longer to eliminate artemisinin-resistant parasites. However, if resistance to artemisinin spreads, "there are no new drugs to take the place" of ACTs and no "immediate prospects under development," the Times reports. Pascal Ringwald, malaria coordinator at the World Health Organization and co-author of an upcoming study on the topic, said artemisinin-resistant malaria "could spread in any direction," adding, "[W]e have to make sure it doesn't." Timothy Ziemer, head of the President's Malaria Initiative, called the apparent rise in drug resistance "significant," adding, "This is something we can't just slide under the carpet."

According to Fukuda, Cambodia's border with Thailand is the "canary in the coal mine" for drug-resistant parasites. Resistance to the malaria drug chloroquine began in this area in the 1950s, and chloroquine now is considered ineffective against malaria in most regions of the world. Several factors could account for the history of drug resistance in this region, including the movement of migrant workers, civil unrest, counterfeit medications and a lack of funding. In addition, a widespread use of malaria drugs could lead to an increase in drug resistance, John MacArthur, infectious disease expert at USAID in Bangkok, said. However, Nicholas White, malaria expert and chair of a joint research program between Oxford University and Mahidol University in Thailand, said that despite reports of rising drug resistance, artemisinin "still works in Cambodia, maybe not as well as before," adding, "This is not the death knell of artemisinin."

To help combat a rise in artemisinin resistance, the U.S. has approved a malaria monitoring center in Myanmar and the Bill & Melinda Gates Foundation has granted $14 million to the Cambodian and Thai governments to establish a malaria containment program. According to Duong Socheat, director of Cambodia's National Malaria Center, the program will include insecticide-treated net distribution, malaria screenings for high-risk populations and follow-up visits by health workers to evaluate drug effectiveness. In addition, the government will employ "motorcycle microscopists" to take blood samples, analyze them and distribute malaria treatments. Alan Magill, researcher at the Walter Reed Army Institute of Research, said health experts should address the issue more aggressively, adding that drug-resistant malaria "should be a global emergency that is addressed in a global fashion" (Fuller, New York Times, 1/27).