In 1973, Satoshi Ōmura discovered the extraordinary microorganism that produces the avermectins (from which ivermectin is derived) that originates from a single microbe unearthed from soil in Japan. It was sent to Merck laboratories to be run through a specialized screen for anthelmintics in 1974 and the avermectins were found and named in 1975.

Perhaps more than any other drug, ivermectin is a drug for the world’s poor. For most of this century, some 250 million people have been taking it annually to combat two of the world’s most devastating, disfiguring, debilitating and stigma-inducing diseases, Onchocerciasis (River Blindness) and Lymphatic filariasis (elephantiasis).

The first publications on avermectin appeared in 1979, describing it as a complex mixture of 16-membered macrocyclic lactones produced by fermentation of the actinomycete Streptomyces avermitilis—later re-classified as S. avermectinius. The avermectin family displayed extraordinarily potent anthelmintic properties. Marketed in 1981, it quickly became used worldwide to combat filarial and other infections and infestations in livestock and pets.

Registered for human use in 1987, ivermectin was immediately donated as Mectizan tablets to be used solely to control Onchocerciasis, a skin disfiguring and blinding disease caused by infection with the filarial worm Onchocerca volvulus, which afflicted millions of poor families throughout the tropics.