William Campbell, Satoshi Ōmura, and Youyou Tu

William Campbell, Satoshi Ōmura, and Youyou Tu

Updated: Nobel Prize honors drugs that fight roundworms, malaria

Three scientists have been awarded the 2015 Nobel Prize in Physiology or Medicine for decades-old findings that led to “revolutionary treatments” for devastasting diseases in the developing world. William Campbell of Drew University in Madison, New Jersey, and Satoshi Ōmura of Kitasato University in Tokyo share half of the prize for discovering avermectin, a drug to kill roundworms that cause blindness and deformities. The other half of the prize goes to Youyou Tu of the China Academy of Chinese Medical Sciences in Beijing, who discovered and refined artemisinin, which has proved highly effective against severe cases of malaria.

“The global impact of the discovery and the impact on mankind is immeasurable,” Hans Forssberg, a neuroscientist and member of the Nobel Assembly, which selects the winners, said today at a press conference announcing the award. 

“It is extremely rewarding to know that people from the development community have been recognized for work that really helps people,” says David Molyneux, who heads the neglected tropical diseases program at the School of Tropical Medicine in Liverpool, U.K. Molyneux estimates that ivermectin, a derivative of avermectin, has been given more than a billion times, preventing more than 500,000 cases of blindness.

Ōmura, a microbiologist, was searching for useful compounds from soil bacteria in Japan, and he developed methods for large-scale culturing and studying of these microbes. From thousands of cultures of Streptomyces, he identified some 50 that appeared to be strong candidates for antimicrobial drugs. Studying these strains, Campbell found that one was particularly effective at killing roundworms in farm animals and pets. The active component was purified and named avermectin. Subsequent versions have been so effective at curing the parasitic diseases river blindness and lymphatic filariasis—which causes gross deformities—that the diseases have been nearly eradicated.

The key findings were described in these two papers, both published in 1979 in Antimicrobial Agents and Chemotherapy.

The prize came as a big surprise to Ōmura. ”I humbly accept it,” he told the media arm of the Nobel Foundation in a telephone interview today. "I'm still not sure it's quite right for me to receive this award," he said later in an interview with the Japanese broadcasting company NHK. "There are many talented researchers in Japan. What I do is just tedious labor. I never really expected myself to be a Nobel laureate. I've always been proud that my work helped people, I tried to help people. But that is different from being a Nobel laureate."

“I’m in shock,” Campbell told ScienceInsider. Unlike the Nobel Peace Prize, scientific Nobels cannot be awarded to more than three people, he notes, “so I assumed there was no way the prize could be given for this, because it was a group effort.” Although team efforts are standard in science, he says, “this was a team of teams.”

The path from Ōmura’s soil sample to a drug used in African villages was long, Campbell says, and there were few “Eureka” moments along the way. “One develops a very subdued form of excitement,” he says. “You don’t assume this is going to make it all the way to the marketplace or the clinic.”

Pharmacologist Youyou Tu also found an important drug from natural sources. Searching though historical records of traditional Chinese medicine, she noticed that sweet wormwood was in hundreds of recipes for treating malaria. When she tested extracts in mice, she saw hints of an effect, but the studies were inconclusive. A recipe in a 1700-year-old book led Tu to a new method to extract the active compound. This turning point led to the drug artemisinin, which acts effectively on the early stage of the parasite’s life cycle. The drug has “remarkably reduced the death toll during last decades” for hundreds of millions of people infected with severe malaria, Forssberg said.  

Tu won the Lasker Award in 2011 for her work on artemisinin—the first Chinese scientist to get that award. But many scientists in China were outraged that she was singled out; they argued that the discovery was a mass effort involving thousands of researchers and that credit should not be Tu’s alone. The drug was borne of Project 523 (named for the 23 May 1967 date of its founding), an ambitious research arm of the People’s Liberation Army working on orders from Chairman Mao Zedong to find a cure for malaria.

Historians say that Tu entered the research project later than other researchers, when many of her colleagues were exhausted by both their work and the ongoing political struggles that had engulfed China. Others defended Tu during the Lasker controversy, however. She has maintained a low profile herself.

With reporting by Dennis Normile, Kathleen McLaughlin, and Christina Larson.

*Update, 5 October, 10:32 a.m.: This story was updated with new information about Tu and comments from William Campbell and other researchers.