Illustration of the Irish-US parasitologist William C Campbell (born 1930). Campbell is best known for his discovery of avermectins, a group of drugs that treat parasitic infections including river blindness and elephantiasis. He isolated the compounds from a soil bacterium discovered by Satoshi Omura. Avermectins have treated hundreds of millions of people. Campbell was awarded a share of the 2015 Nobel Prize in Physiology or Medicine along with Omura for their work on avermectins and Tu Youyou for her work on antimalarial drugs.