Three scientists were awarded the Nobel Prize in Physiology or Medicine for discovering “therapies that have revolutionized the treatment of some of the most devastating parasitic diseases,” the Nobel committee announced on Monday.
William C. Campbell and Satoshi Omura won for developing a new drug, Avermectin. A derivative of that drug, Ivermectin, has nearly eradicated river blindness and radically reduced the incidence of filariasis, which causes the disfiguring swelling of the lymph system in the legs and lower body known as elephantiasis. They shared the $900,000 award with Youyou Tu, who discovered Artemisinin, a drug that has significantly reduced death rates from malaria.
“These two discoveries have provided humankind with powerful new means to combat these debilitating diseases that affect hundreds of millions of people annually,” the committee said in a statement. “The consequences in terms of improved human health and reduced suffering are immeasurable.”
Parasitic worms afflict a third of the world’s population, particularly in sub-Saharan Africa, South Asia and Latin America. Malaria, a mosquito-borne disease caused by single-cell parasites that invade red blood cells, kills more than 450,000 people a year, most of them children.
“After decades of limited progress in developing durable therapies for parasitic diseases, the discoveries by this year’s laureates radically changed the situation,” the committee said.
Dr. Omura, a microbiologist, is an expert in isolating natural products. He collected and tested scores of soil samples for Streptomyces, bacteria that live in the soil and produce antibacterial agents. Dr. Omura isolated new strains of Streptomyces from soil samples and cultured them in the laboratory. From thousands of cultures, he selected about 50 of the most promising ones. One later turned out to be Streptomyces avermitilis, the source of Avermectin.
Dr. Campbell, an expert in parasite biology who worked for decades at the Merck Institute for Therapeutic Research, obtained cultures from Dr. Omura. He documented that one of the cultures yielded a substance that was remarkably effective against parasites in domestic and farm animals. He purified the substance and named it Avermectin, which was subsequently chemically modified to a more effective compound called Ivermectin. Further chemical tests produced Ivermectin that killed parasites in infected humans.
“Collectively, Omura and Campbell’s contributions led to the discovery of a new class of drugs with extraordinary efficacy against parasitic diseases,” the committee said.
Dr. Tu won a Lasker Award in 2011 for her discovery of Artemisinin. During the Cultural Revolution, in the 1960s, the Chinese government began a project to find a new malaria drug that could replace the standard treatment, quinine and chloroquine, which was losing effectiveness as malaria parasites developed resistance.
Dr. Tu and her colleagues pored over the literature on ancient Chinese remedies and collected 380 extracts from 200 herbs that offered promise. One of the plants they studied was sweet wormwood, or Artemisia annua, which was used by Chinese herbalists centuries ago to treat fever.
Because of inconsistencies in test results, Dr. Tu went back to ancient Chinese writings and discovered clues to identify and extract the active component of the Artemisia herb. “Tu was the first to show that this component, later called Artemisinin, was highly effective against the malaria parasite, both in infected animals and in humans,” the Nobel committee said.
Today, Artemisinin and its derivatives are typically coupled with other therapies as the “first-line treatment” to combat malaria.
Artemisinin, when used in combination therapy, is estimated to reduce mortality from malaria by more than 20 percent over all, and by more than 30 percent in children. In Africa alone, it saves more than 100,000 lives each year.
Although malaria parasites have developed resistance against Artemisinin in Asia — but not Africa — the committee said its award was for what the drug has done for humans to this point. Success in antimalarial therapy depends on how clever scientists are in using combinations of drugs.
Dr. Campbell, who was born in 1930 in Ramelton, Ireland, worked for decades at the Merck Institute. He is now a research fellow emeritus at Drew University in Madison, N.J. Dr. Omura, who was born in 1935 in Yamanashi Prefecture, Japan, is a professor emeritus at Kitasato University in Tokyo. Dr. Tu, born in 1930 in China, has been a scholar at the China Academy of Traditional Chinese Medicine, now known as the China Academy of Chinese Medical Sciences, since 1965.