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Mosquito Week

What It Takes to Wipe Out Malaria

My visit to Cambodia, which is trying to eliminate the disease for good.


Many tourists know Siem Reap, Cambodia, as the base for exploring the beautiful 12th-century ruins at Angkor Wat. But when Melinda and I stopped there last week, we weren’t thinking about visiting a historic site. In fact we may have been the first visitors who ever passed through Siem Reap and skipped the temples completely.

We were on our way to see another piece of history in the making—Cambodia’s effort to eliminate malaria from within its borders. What we saw may eventually point the way toward a goal that’s shared by many of us in the global health community: eradicating malaria.

Malaria is one of the biggest killers of children on the planet, and Cambodia has made phenomenal progress fighting it over the past decade or so. Deploying an army of more than 3,000 village malaria workers who administer tests, give out medicine, and distribute bednets, they have reduced malaria from about 130,000 cases in 2000 to about 2,000 in 2012. Now the goal is to build on this progress by wiping out malaria entirely within Cambodia.

From Siem Reap, Melinda and I traveled to the remote province of Pailin in western Cambodia, near the border with Thailand, where researchers are running a pilot project to explore the best way to eliminate malaria.

They face a number of obstacles in their work. One is a kind of arms race, as drug-resistant strains of the malaria parasite keep emerging. For reasons that are not entirely clear, some of the most effective drugs against malaria have been rendered useless in Cambodia. There’s the potential for a real nightmare scenario here. If a strain of malaria that’s resistant to artemisinin were to spread to Africa—where artemisinin is the most commonly used anti-malarial drug—it would be the worst disaster ever in malaria control. But if we can eliminate malaria in Cambodia, we can not only save the lives of Cambodians, we can also prevent any new drug-resistant strains from developing and spreading to other places.

Another obstacle to eliminating malaria is that people can be infected by the parasite without showing any symptoms. Because the parasite is in their blood, they can transmit it to other people via mosquitoes, and those people can get very sick or die. The parasite is sort of like a James Bond villain who finds a secret lair from which he can carry out his deadly plot, undetected. So we need to treat everyone who’s infected, even if they don’t look or feel sick.

The project in Pailin is designed to try to get over these obstacles. The idea is to test everyone in the community to see who’s carrying the parasite and how much of it they’re carrying. Anyone who tests positive is given free treatment with the latest drugs. Here’s a video where I explain how it works:

Of course, there are downsides to this approach. People who don’t feel sick can be reluctant to get tested or take medicine. It’s also hard to keep people participating in the project, because they have to give blood every three months. So it was great to hear that Pailin’s village malaria workers, who have spent years building up trust in the community, are helping the project get over these hurdles.

Melinda and I met one of them, a man named Long Vuthy. He has been a village malaria worker since 2003 and is also the village leader. He told us he decided to join the program after watching the disease devastate his community. He proudly showed us his malaria kit—a tackle box containing tests, medications, and a log book where he records each case he encounters.

After meeting Mr. Vuthy, we walked to a local school where the screening is taking place. That morning, about 120 people had come to get their blood drawn and tested for the malaria parasite. They also answered a few questions designed to find out whether they might have been exposed to the parasite (e.g., “Do you work in the forest?”). For their trouble, they were paid a day’s wages, the equivalent of about $2.50, and got a free lunch.

As you might imagine, a project this involved would be hard to scale up using the drugs and diagnostics we have today. For example, the blood samples have to be shipped 250 miles to a lab in Bangkok that can run more-sensitive tests; that’s one reason our foundation is investing in a highly sensitive test that could be used in the field. We’re also funding research on new drugs that would cure malaria with one dose instead of the several doses now required. The fewer the doses, the more likely it is that patients will take all of them, and the more likely that the parasite will be killed off completely, which prevents drug resistance.

A lot more work needs to be done in the years to come. But I left Cambodia thinking that if we can be successful there, it will be a giant step toward the long-term goal of wiping out malaria everywhere.