Beating Malaria

Last summer, I traveled to the Thai-Burmese border to report on the pioneering physicians who have been on the front lines of developing artemisinin, the World Health Organization's drug of choice for combating malaria. That trip is now the cover story in The Scientist magazine, which can be viewed here (subscription required).

Here's an excerpt:

If a research team led by Francois Nosten and his mentor, Nicholas White of Mahidol University in Bangkok (whom many consider the world's leading malariologist), lead the way to better protocols for treating pregnant women and others with artemisinin-combination therapy (ACT), it won't be the first time that the duo has used the tools of clinical science to teach the world new methods for combating this age-old scourge. In 2001, the World Health Organization (WHO) declared ACT the preferred method for treating malaria, especially the most deadly form of the parasite, Plasmodium falciparum, which in most parts of the world has evolved resistance to older drugs such as chloroquine. WHO's 2001 decision was based largely on clinical trials that SMRU had conducted during the early 1990s.

This breakthrough came despite the fact that artemisinin's mechanism is poorly understood. When the parasite invades a red blood cell to reproduce, it destroys the hemoglobin and frees up iron. In the presence of artemisinin, this free iron forms highly reactive oxygen radicals that some scientists believe inhibit the parasite's ability to digest more hemoglobin, thus breaking the chain in its lifecycle. By contrast some older drugs such as chloroquine disrupt membrane function, thus disabling the invaded blood cell's ability to disgorge the newly formed parasites.

Not knowing the chemistry hasn't stopped the drug's deployment in the field, though. Early in this decade, Nosten and colleagues at the Shoklo Malaria Research Unit spearheaded a joint public health program with the Thai government that trained rural health workers, most of them recruited from local villages, to use test kits to diagnose malaria and then administer ACT. The campaign also attacked the Anopheles mosquito that spreads the disease by conducting indoor home spraying with deltamethrin, a pyrethroid ester insecticide considered one of the safest in the world. (DDT, recently resuscitated by WHO, was banned in Thailand in 1997.) Distribution of insecticide-treated bed nets was also part of the campaign.

The result? Malaria in mountainous Tak province was reduced by 34% and mortality was cut in half. Though the program was cut short when the Thai government's funds were depleted, it proved that even in remote areas, where people live exposed to the elements and have no formal healthcare system, it is possible to roll back malaria.

That's the goal of the campaign that world health officials launched in 1998 to cut the incidence of malaria in half by 2010. The campaign has so far fallen woefully short of expectations. This year will see an estimated 500 million cases of malaria, two-thirds more than the 300 million cases estimated in 1999. Somewhere between one and two million people will die of the disease, most of them children under the age of five in sub-Saharan Africa.

To Nosten, who has devoted his life to fighting the resurgence of drug-resistant malaria, it's inexplicable that global health officials and policymakers haven't moved faster to deploy the knowledge and tools that he helped to create - especially the three-day regimen of ACT. (Two combinations tested by Nosten and colleagues included artemether-lumefantrine and mefloquine-artesunate, both of which proved more than 96% effective against P. falciparum.) "The death toll is enormous. It's like five jumbo jets filled with children crashing every day," he says. "By 2010, there could be twice as much malaria. That, to me, is a failure."