To prevent a recurrence with artemisinin therapies, the United States has put aside political considerations and approved a malaria monitoring center in military-run Myanmar, formerly Burma. The Bill and Melinda Gates Foundation, one of the largest donors to malaria research, is giving $14 million to the Thai and Cambodian governments to help pay for a containment program.

That program includes efforts to supply the area with mosquito nets, a screening program for everyone living in affected areas and follow-up visits by health workers to assess the effectiveness of the drugs, said Dr. Duong Socheat, director of Cambodia’s National Malaria Center. On the Thai side of the border, the government has “motorcycle microscopists” who take blood samples from villagers and migrant workers, analyze them on the spot and distribute antimalaria drugs.

But some experts would like to see an even more aggressive approach.

“Many of us think this should be treated on the same order as SARS,” said Col. Alan J. Magill, a researcher at the Walter Reed Army Institute of Research in Maryland. “This should be a global emergency that is addressed in a global fashion.” SARS, the respiratory disease that spread rapidly through Asia and beyond in 2003, killed more than 700 people.

The falciparum parasite is one of four types of malaria and by far the most virulent. It enters the bloodstream through a mosquito bite, and after incubating about two weeks, it multiplies and takes over red blood cells. There it causes fever, chills, headaches and nausea, among other symptoms. If untreated, the infected cells can block blood vessels and fatally cut off blood supply to vital organs.

The recent studies show that artemisinin-based drugs are becoming less effective in removing the parasite from the bloodstream. While a few years ago it took the drugs 48 hours to clear the bloodstream of parasites, it now can take 120 hours.

“What our study demonstrates is that therapy for some patients fails  the malaria goes away and comes back,” said Lt. Col. Mark M. Fukuda, a United States Army doctor whose study was published in The New England Journal of Medicine in December.

Different regions rely on different artemisinin combinations. The Cambodian government recommends that artemisinin be combined with mefloquine, which was developed by the American military and is known commercially as Lariam. Artemether, a derivative of artemisinin, is often combined with another antimalarial drug, lumefantrine. This was recently judged to be the most effective combination in a study of children in Papua New Guinea.