Three researchers who exploited naturally occurring compounds to fight parasitic diseases have shared the Nobel Prize in Physiology or Medicine. William Campbell, an American, and Satoshi Omura, from Japan, discovered avermectin, a compound extracted from naturally occurring bacteria that quickly kills parasitic worms. A derivative of avermectin, ivermectin, is now the first-choice medicine against worm-caused diseases, such as river blindness and lymphatic filariasis. Tu Youyou, a Chinese scientist, was honoured for discovering artemisinin, a potent anti-malarial drug. She isolated artemisinin, which is derived from sweet wormwood, a common plant, in the 1960s while working on a Chinese military research project that screened traditional medicines for anti-malarial potential. Thanks partly to discoveries like these, the global burden of parasitic disease is easing. The World Health Organisation calculates that deaths from malaria have fallen by half since 2000, to (a still-dreadful) 438,000 expected this year, mostly children. There is talk of eradicating river blindness altogether.