MADISON – William C. Campbell, a master’s and doctoral graduate of the University of Wisconsin-Madison, was awarded a share of the 2015 Nobel Prize in Physiology or Medicine.

Campbell was given half the prize along with Satoshi Omura for their work leading to the discovery of the drug avermectin, derivatives of which played an important role in dramatically lowering the incidence of the tropical diseases river blindness and lymphatic filariasis, commonly known as elephantiasis, and both of which afflicted tens of millions of people in the world’s tropical regions.

Working with cell cultures of different strains of the soil bacterium Strepotmyces, discovered and cultured by Omura, Campbell showed that a component of one of the cultures was remarkably effective against parasites in domestic and farm animals. Purified, the agent was named avermectin. A chemical modification of the drug, known as ivermectin, was later tested in humans and shown to safely and effectively control the microscopic parasitic larvae that cause serious human diseases in the tropics. Introduced for use in humans in 1982, the drug is highly effective and freely available worldwide.

“Ivermectin is absolutely critical to the effort to control these diseases and has helped millions of people in the developing world,” according to Bruce Christensen, a UW-Madison parasitologist who helped prepare materials in support of a UW-Madison honorary degree awarded to Campbell in 2005. “The populations that needed this drug the most are in some of the most destitute regions of the world.”

River blindness, explains UW-Madison pathobiological sciences Professor Tim Yoshino, has been nearly eradicated thanks to Campbell’s discoveries and the work of the Carter Center, which, working with the drug manufacturer Merck, has distributed more than 225 million free doses of the drug. “These drugs have made a tremendous impact on animal and human health,” says Yoshino. “They’ve been revolutionary in terms of the long-term prevention of heartworm in dogs and cats.”

The drug discovered by Campbell and Omura is used to control parasites in dogs, horses and other livestock. It was the efficacy of the drug on a horse parasite similar to the one that causes river blindness, notes Christensen, that inspired Campbell to seek testing of the drug in humans.

As an agent of importance to veterinary medicine, ivermectin has been used widely in small animal practice since the 1980s, according to Sandi Sawchuk, a clinical instructor at UW-Madison’s School of Veterinary Medicine. “Since ivermectin hit the small animal pharmaceutical market other avermectin drugs have been discovered – selemectin, moxidectin and milbemycin. All are used for heartworm prevention but also intestinal parasites and ear mites. These drugs have made a huge impact on veterinary practice and pet health. I can’t imagine practicing without them,” says Sawchuk.

[pullquote]The drug discovered by Campbell and Omura is used to control parasites in dogs, horses and other livestock. [/pullquote]

The citation from the Nobel Assembly at the Karolinska Institute, which annually confers the prestigious prizes, states that the “importance of ivermectin for improving the health and wellbeing of millions of individuals with river blindness and lymphatic filariasis, primarily in the poorest regions of the world, is immeasurable.”

A native of Ramelton, Ireland, Campbell came to the United States after earning his undergraduate degree from the University of Dublin’s Trinity College in 1952. He received his master’s degree in veterinary science in 1953 from UW-Madison and went on to earn a UW-Madison doctorate in zoology in 1957. From 1957 to 1990, Campbell worked at the Merck Institute for Therapeutic Research. He is currently research fellow emeritus at Drew University in Madison, New Jersey.

China’s YouYou Tu was awarded the other half of the medical Nobel for her discoveries related to the antimalarial drug artemisiner.