Ian Williams / NBC News
Testing for malaria in a village near Pailin, Cambodia.
PAILIN, Cambodia – The border crossing between Thailand and Cambodia at Pailin has a rather bleak feel about it at the best of times. In the heavy monsoon rain, the dingy checkpoints are reduced to gray smudges. But a little beyond, on the Cambodian side, the neon of a casino beckons those Thais willing to brave the downpour for gambling tables, illegal in their country.
Until the late 1990s, these border areas were the last holdout of the murderous Khmer Rouge, which was responsible for the deaths of an estimated 1.5 million Cambodians.
But this mosquito-infested area now has another sinister claim to fame – for deadly malaria. This is the region where resistance to just about every major anti-malarial drug has first taken hold.
And history shows that once resistance emerges, it can quickly spread worldwide, rendering the drugs useless in the fight against a mosquito-borne parasite that still kills nearly a million people worldwide each year, most of them in Africa.
The Khmer Rouge have now been defeated, but not drug-resistant malaria. The Pailin area is now the epicenter of a fight to contain a growing resistance to Artemisinin, which is the world's main anti-malarial drug.
"We've got to contain the parasite before it spreads throughout the region. If that happens it’s going to be a public health emergency," said Dr. Najibullah Habib, spearheading the containment project on behalf of the World Health Organization.
We met Habib not far from the border, where hundreds of health workers are moving from village to village, testing everybody, a pre-emptive strike to try to find, treat and monitor those with malaria symptoms.
"If we lose this first-line drug, this Artemisinin, then we are lost," said Christopher Raymond, an American drug specialist working with the project. He said that as of today there is no good backup if malaria becomes Artemisinin-resistant.
The alarm was first sounded by U.S. Army researchers, who showed that in the border areas Artemisinin was taking far longer to clear malaria than in the past.
Ian Williams / NBC News
Malaria victim at the public hospital in Anlong Veng, Cambodia.
"It was clear that the parasites are becoming less susceptible to the drug," said David Saunders of the Armed Forces Research Institute of Medical Sciences (AFRIMS), which has now extended its study further along the border.
"We've really come in at a crucial time," said Saunders' colleague Stuart Tyner. "We're fortunate to have identified this now," he added, "at a time when it’s just becoming an issue."
He says there is still time to fight it, and working with Cambodian health officials their aim now is to see if it is spreading, how fast, and to test different combinations of drugs to fight it.
"It's harder for parasites to develop resistance to multiple drugs," Tyner told me as he studied through a microscope parasites recently extracted from a patient in the public hospital at Anlong Veng, where AFRIMS has set up a state-of-the-art laboratory.
They also want to learn how the parasite develops its resistance.
While U.S. experts are playing a crucial role in the research and containment projects, USAID and the Gates Foundation are throwing millions of dollars into the battle.
But why this border? Why has resistance always started here?
Experts speculate that conflict, poverty and a lot of migrants moving across the border have all played a part.
Resistance also spreads when people don't take drugs properly, and counterfeit and sub-standard drugs are also to blame. They have been rife in the border areas.
"It's a race against time," said Christopher Raymond, an expert in counterfeit drugs, whose project is backed by U.S. Pharmacopeia and USAID. He's been part of a blitz on local pharmacies.
He says the fake drugs are often very good, though others contain just a pinch of the real thing.
"It's like putting out a fire with gasoline. It’s eventually going to explode into resistance because you are constantly under-treating it."
They have also banned the use of pure Artemisinin, figuring that the life of the drug can be better extended if it is used in combination with others.
Ian Williams / NBC News
After the rains. late afternoon near Pailin, the epicenter for drug-resistant malaria.
Officials say they are having an impact, though separately a Cambodian colleague said he was still able to buy banned anti-malarial drugs in three of six pharmacies he visited.
And before Christmas the WHO warned that a suspected drug-resistant strain of malaria has now been found along the Thai-Myanmar border and in a province of Vietnam – an ominous development.
Cambodia's rain-soaked border areas hardly look like the epicenter of anything, but the stakes are high: What happens here over coming months could impact the health of millions worldwide.