The medicines they helped develop are credited with improving the lives of millions. And now three researchers working in the U.S., Japan and China have won the 2015 Nobel Prize in Physiology or Medicine. Among the winners: William C. Campbell of Drew University in Madison, N.J., for his work on the roundworm parasite.
Born in Ireland, Campbell shares half the prize with Satoshi Omura of Kitasato University in Japan, who has researched the same parasite. The other half of the award goes to Youyou Tu of the China Academy of Traditional Medicine in Beijing, China, for her work in developing therapies for malaria.
Taken together, the three "have transformed the treatment of parasitic diseases," according to the Nobel Prize committee. "The global impact of their discoveries and the resulting benefit to mankind are immeasurable."
All of the researchers were born in the 1930s; much of their key research was published around 1980. And their findings came after intense searches for existing natural components that might help fight diseases.
Working in Japan, Omura isolated novel strains of streptomyces bacteria from soil samples that not only had antibacterial components, but also had the potential to combat other harmful microorganisms.
In the U.S., Campbell explored the effects of Omura's streptomyces cultures and found that, as the Nobel committee says, "a component from one of the cultures was remarkably efficient against parasites in domestic and farm animals."
The active compound, called avermectin, was further developed to become ivermectin, which is now used around the world to protect people and animals from a range of parasites, from river blindness to lymphatic filariasis (also known as elephantiasis).
"I humbly accept this prize," Omura said when he was contacted by the Nobel committee Monday. Saying there are "many, many researchers" who are doing important work, he added, "I may be very, very lucky."
Anecdotes have long held that Omura found the life-changing soil sample while he was doing what he loved: playing golf. He clarified that a bit Monday, saying it had happened "very close to the golf course."
Tu revolutionized how malaria is fought by applying ancient techniques from China's traditional herbal medicine to isolate and purify a component from the plant Artemisia annua that could fight malaria in animals and people.
Tu used those insights to extract the component, now known as artemisinin, and to show that it could beat malaria. The Nobel committee says artemisinin represented "a new class of antimalarial agents that rapidly kill the malaria parasites at an early stage of their development, which explains its unprecedented potency in the treatment of severe malaria."
The plant that yielded the compound, Artemisia annua, is also known as qinghao, sweet wormwood and sweet Annie. Its use in traditional Chinese medicine dates back more than 2,000 years.
The work that led to the discovery of artemisinin began in the late 1960s, when China launched a large-scale effort to develop an antimalarial treatment to protect North Vietnamese soldiers from the deadly disease.
To illustrate how malaria works — and how humans have fought it — NPR's Adam Cole produced a video feature in 2012, explaining how that story ranges from the use of quinine (and the gin and tonic) to the Vietnam War.