The Nobel Prize in Medicine has been jointly awarded to William C. Campbell and Satoshi Ōmura, for developing a therapy to treat infections from roundworm parasites, and Tu Youyou, for her discovery of a therapy to treat malaria. Tu, a Chinese medical scientist, becomes the 12th woman to win the Nobel Prize for medicine. The three scientists will share an award of 8 million Swedish Krona ($946,488).

Campbell and Ōmura each made discoveries that led to the development of new drugs that effectively treat river blindness and lymphatic filariasis (elephantiasis). Their work has also led to therapies that have proven effective against other parasitic diseases. Tu discovered the drug Artemisinin, which has significantly reduced mortality rates among patients suffering from malaria.

"The two discoveries have provided humankind with powerful new means to combat these debilitating diseases that affect hundreds of millions of people annually," the Nobel Prize Committee said Monday. "The consequences in terms of improved human health and reduced suffering are immeasurable."

Ōmura, a Japanese microbiologist, isolated new strains of Streptomyces, a group of soil-based bacteria that was known to produce antibacterial agents. He identified 50 strains as the most promising, and Campbell, an Irish scientist working in the US, later acquired them for further study. In one strain, Campbell identified a component that was particularly effective against parasites in domestic animals. The component was purified and named Avermectin, which was then modified to create a chemical compound called Ivermectin. Ivermectin was shown to wipe out parasite larvae in humans, giving rise to a new class of drugs to treat parasitic infections.

Tu, 84, used traditional herbal medicine to identify a component that was later called Artemisinin. She singled out the component after testing a range of herbal remedies in malaria-infected animals. She was the first to show that Artemisinin, an active component extracted from the plant Artemisia annua, was effective in treating the malaria parasite in both animals and humans.

Tu made the discovery while working at a secret drug development project launched by Mao Zedong during the 1960s and 1970s. The New Scientist published a profile of her in 2011, detailing how she was forced to leave her daughter to travel to the province of Hainan, where she saw the impacts of malaria first-hand. Today, the drug she discovered is used in all malaria-impacted parts of the world, where it has reduced mortality rates by more than 20 percent overall, and more than 30 percent in children.

"It is scientists' responsibility to continue fighting for the healthcare of all humans," Tu told The New Scientist in 2011, after she won the Lasker Prize for her work. She added: "What I have done was what I should have done as a return for the education provided by my country."