At the turn of the millennium, a new class of drugs derived from ancient Chinese herbal medicine revolutionized malaria care. Artemisinin's, as they're called, are based on extracts from the sweet wormwood plant. They arrived just as the drugs used since the 1970s were becoming useless for many, as the parasite that causes malaria evolved resistance.

"The deaths we saw in the late 1990s, the early 2000s — like 2 million a year — that was a direct result of drug failure," says George Jagoe , executive vice president of access and product management at Medicines for Malaria Venture, a non-profit. "No one ever wants to be behind the 8-ball again."

Artemisinins have saved millions of lives since then and are now the foundation of malaria treatment worldwide. But there are worrying signs

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