Villages that used to boast a few ponds or a wide well as their water source can wipe out the infection by switching to a type of well that you don’t stick your feet into. Methods like this brought infection rates down from 40 million in the middle of the twentieth century to 3.5 million in 1986, when the World Health Organization and the Carter Center began an anti–guinea worm campaign, and to just 22 reported cases in 2015.
