President Jimmy Carter said Wednesday that his health is good enough that he hopes he will live to see the end of Guinea worm, a parasitical disease he has led the fight against since the 1980s.

He was at the Carter Center to talk about the opening of a new exhibit at the Jimmy Carter Library and Museum, “Countdown to Zero,” about the world’s efforts to eradicate a number of diseases.

Carter, in an exclusive interview with The Atlanta Journal-Constitution, said the cancer he battled and that he feared would take his life has not reappeared and he still hopes to see the end of the disease declared.

“Since last January the MRI scans of my liver and my brain have not revealed any remaining melanoma or cancer … I feel confident about it, yes,” he said. “I never really lost my confidence except about year and half ago when I thought was going to die for a few weeks.”

When the Carter Center targeted Guinea worm in the 1980s as a disease that the former president pledged to use his influence to eliminate, there were 3.5 million cases in 21 countries. Carter announced Wednesday that there are now only three countries where the disease remains, down from four last year. There were 25 reported cases in 2016 in remote villages in Ethiopia, Chad and South Sudan.

The disease is picked up by drinking water that contains larvae of the parasitical worm. After completing its life cycle in the human body, the long, thread-like worm, about the diameter of a kite string, erupts from the skin of the host and can take days or weeks to work itself out.

The Carter Center has worked with governments, health agencies and nonprofits across the world, with President Carter often opening doors that had been closed, to kill off the disease.

He is headed to Washington for the nomination of President-elect Donald Trump. He said he hopes to talk to people in the new administration about continuing U.S. support for disease-elimination programs.