Nobel Peace Prize winner Jimmy Carter spent decades waging war against an ancient parasite.

The Carter Center said Tuesday that only 13 human cases of Guinea worm disease were reported worldwide last year.

The U.S.-based Carter Center, which leads the eradication campaign, says just 27 cases were reported in 2020 in six countries in sub-Saharan Africa, or half the number of cases in 2019. Despite cuts to many programs worldwide, The Carter Center said its community-based program to eradicate Guinea worm remained up to 95% operational. “We’re reporting a 50% reduction in human cases, down to only 27 people in the world last year that had Guinea worm. Unlike other diseases that are controlled by medicines or vaccines, Guinea worm can be eradicated by training people to filter and drink clean water. Contracted by drinking infected water, Guinea worm disease affects some of the world’s most vulnerable people.