In the 1970s, microbiologist Satoshi Ōmura at Japan's Kitasato Institute isolated a soil bacterium that produced compounds effective against parasitic worms. Working under a partnership with Merck, parasitologist William C. Campbell's team refined these compounds into ivermectin, a veterinary treatment approved in 1981 and later adapted into Mectizan, approved for human use in 1987 to treat river blindness. Merck committed to donating Mectizan indefinitely to combat the disease, and Ōmura and Campbell shared the 2015 Nobel Prize in Physiology or Medicine for the discovery.