Malaria Shows Its Soft Spot

Lucky finding. The Plasmodium parasite--seen here in the gut of a mosquito--can be killed with a common antibiotic.

An antibiotic that helps fight zits and bad breath may be able to prevent a much more serious disease. In the February issue of Nature Medicine, researchers report that triclosan, often used in mouthwash and acne creams, can cure mice of malaria. The study also describes a new biochemical pathway in the malaria parasite that could be the target of several other drugs.

With 2.7 million deaths per year, malaria remains one of the most ruthless killers of the tropics. And because the parasite tends to evolve resistance to every drug, scientists are running out of ideas for curing the disease. Searching for alternatives, Namita and Avadhesha Surolia, of the Jawaharlal Nehru Centre for Advanced Scientific Research in Jakkur, India, infected mice with the malaria parasite and then injected them with triclosan. "We just thought we'd give it a try," says Namita Surolia. The two researchers were surprised to see that the animals were all cured within 4 days and stayed healthy, while other malaria-infected mice died after a week.

The success was intriguing, because triclosan attacks one of the enzymes that help produce fatty acids--the stuff that cell membranes are made of--in plants and bacteria. But the Plasmodium parasite that causes malaria is an entirely different single-celled organism, and until recently researchers thought it didn't have the biochemical pathways to produce fatty acids. (Instead, they presumed that Plasmodium borrowed its fatty acids from its animal host.)

The Surolias went on to show that, like in bacteria, triclosan is the wrench that jams Plasmodium's fatty acid machinery; it inhibits one of the key enzymes in the biochemical conveyor belt. This brings the fatty acid cycle to a grinding halt, and the parasite cannot divide for want of new cell membranes.

Triclosan is normally used externally and might be dangerous to swallow in high doses. But if it turns out to be safe, it could be tested as a malaria treatment in humans, says James Beeson, a malaria researcher at the University of Melbourne, Australia. What's more, all the other enzymes involved in the production of fatty acids have suddenly become potential targets, he says, giving science a much-needed push in the arms race with Plasmodium.

Related sites
World Health Organization malaria fact sheets