By JOHN MURPHY

Bill & Melinda Gates Foundation/ www.impatientoptimists.org

Million Moms Challenge Contributor

Yim Pros, a 12-year-old boy in western Cambodia, waits for treatment for a severe case of malaria. His mother tries to bring down his high fever with a damp towel. (Courtesy of Bill & Melinda Gates Foundation.)

TA SANH, Cambodia–It’s a bumpy, muddy drive on rutted dirt roads, across fast moving rivers and through thick forests to reach this remote corner of Cambodia- so far away that it seems like it could hardly pose a threat to the outside world.

But a health risk has emerged here that could have an impact on millions of people worldwide: drug-resistant malaria.

In 2008, researchers working along the Thai-Cambodian border discovered that the parasite that causes malaria was showing signs of resistance to one of the best drugs we have to fight it.

Malaria, spread through mosquito bites, kills about 800,000 people each year. Most of those deaths occur among children in Africa, yet the disease still remains a fierce foe in Southeast Asia where there are more than 111 million suspected malaria cases each year.

Artemisinin is viewed as one of the most powerful anti-malarial drugs available. Used in combination with other drugs, artemisinin normally cures patients within 48 hours. But several years ago researchers noticed that malaria patients here were taking much longer to respond to the medication – sometimes a week or longer.

This is not the first time anti-malarial drugs have lost their potency in this part of the world. In the 1950s, chloroquine was the drug of choice for battling malaria. But the parasite evolved, developing a resistance to the drug along the Thai-Cambodia border before spreading to India and then Africa.

Now scientists fear that artemisinin will suffer the same fate.

“If we lose that drug there aren’t too many other drugs in the pipeline, and millions of people would be at risk,” Dr. Najibullah Habib of the World Health Organization told me during a visit to Cambodia in September.

In 2009, the World Health Organization, in partnership with the health ministries of Cambodia and Thailand, and other donors, including the Bill & Melinda Gates Foundation, launched an ambitious effort to contain the spread of drug resistant malaria by wiping out the disease altogether in Cambodia.

From the start, the team knew the job wouldn’t be easy in a region struggling with deep poverty, bad roads, and weak government infrastructure.  Adding to the challenge, Cambodia’s history of war and civil unrest has made it one of the most heavily mined areas in the world so travel is slow and hazardous.  For many years, one of the top causes of death here, after malaria, was land mine accidents.

What health officials needed in Cambodia was a new weapon against malaria.

They found it in villagers like Bun Hoy.

Hoy is one of 3,000 people living in this remote corner of western Cambodia who have been trained to diagnose malaria, provide treatment, and educate their communities about the disease. Before this effort, people suffering from malaria here would need to travel hours or sometimes several days to visit a health clinic.

Now volunteers like Hoy provide the first line of defense against malaria on their neighbors’ doorsteps.

On a recent afternoon, I traveled with Hoy as he cared for a farmer with a high fever, chills, and severe aches – the telltale symptoms of this disease. Hoy took the farmer’s temperature, gave him a malaria test, and then treated him with malaria drugs. He then provided follow up care for the next three days to ensure the farmer took his medicine properly and that his condition improved.

Thanks to this intensive health care at the village level, combined with bed net distribution and education efforts, Cambodia has experienced a dramatic turnaround in its fight against malaria.

Malaria cases have dropped by 37 percent in the highest risk area of Cambodia since 2009. Malaria deaths are down 65 percent.

Despite this success, researchers are still puzzled by some basic questions. Why did drug resistance malaria get started in the first place? And why has it always originated in this part of the world?

Poverty, poor medical care, and migration may all contribute to the spread of drug resistance. But experts believe one of the main causes is the widespread misuse of anti-malarial drugs in Cambodia.

Problems occur when patients don’t take the medicines properly or they use fake or substandard drugs. In both cases, if the malaria parasite is not wiped out completely during treatment, it can evolve and start developing resistance to the drugs.

In response, Cambodia is cracking down on the sale of substandard drugs and educating the public about the importance of using safe medicines.

While all of these anti-malaria efforts have helped reduce the threat of malaria in Cambodia, the government and its partners must keep up the momentum to achieve their goal of eliminating this deadly disease altogether.

At Ta Sanh Health Center, a remote medical outpost near the Thai-Cambodian border, health officials are optimistic about their chances. When Dr. Ses Sarim was appointed head of this clinic in 1999, he was treating hundreds of malaria patients each month. So many that they filled up every ward and spilled out onto the health center’s porch.

Today, he treats just two or three malaria cases each month.

Most of the beds once filled with malaria patients are now being used by young mothers giving birth. Given Cambodia’s recent progress against malaria, it’s more than just possible that those children will someday live in a country free of the disease.