Guinea worm disease — a terrible parasite that once affected millions in developing countries — may not be long for this world.

The Carter Center announced Wednesday it documented just 22 cases of Guinea worm in 2015. That's an 83 percent decline from the 126 infections in 2014 — the largest annual decline the group has ever seen.

Guinea worm is a painful, debilitating disease

Guinea worm disease (dracunculiasis) is a painful infection, and it's been around for thousands of years. Once the parasite enters the body it begins to grow, sometimes reaching an entire meter long. From afar, it looks as though it could be a long, thin cord. Removing a Guinea worm has traditionally involved pulling it out of an opening in the skin over several weeks and spooling the parasite around a stick as though it were a string. It’s a tedious process that can result in a secondary infection at the site of the wound.

This is also how Guinea worm spreads: An infected person feels a painful blister forming, typically on the foot. The foot is soaked in water, but that causes the worm to exit the body and burst, leaving hundreds of thousands of larvae in its wake. If this happens in a communal source of water, the cycle begins all over again.

Guinea worm, on its own, is not a fatal disease. But it’s an arduous one that keeps infected individuals from performing daily tasks and supporting themselves. The Carter Center has spent the past three decades implementing community-based education in the affected countries.

Guinea worm used to exist in thousands of African villages. Not anymore.

According to the numbers, these efforts have paid off. In the past year, only four countries reported cases of infection in 20 total villages: Chad, Ethiopia, Mali, and South Sudan. In 1993, 23,735 villages experienced the disease.

Ethiopia reported three Guinea worm cases last year, and there's optimism that there won't be any in 2016. In Chad, there have been reports of domestic dogs contracting Guinea worm. This is unusual since the parasite is typically not found in dogs. But it seems like dogs have been eating raw fish infected with Guinea worm larvae.

Humans cause other challenges too. "Guinea worm reductions in South Sudan and Mali in 2015 are even more remarkable because both countries have significant insecurity or civil unrest and had the largest number of cases in 2014," said Dr. Ernesto Ruiz-Tiben, director of the Carter Center's Guinea Worm Eradication Program, in a press release.

Jimmy Carter is the person to thank

After President Jimmy Carter left the Oval Office, his foundation, the Carter Center, began a campaign to eradicate Guinea worm disease. Since there is no current treatment or vaccine for Guinea worm disease, the center focused on public health preventive strategies to stop the disease from spreading in the first place.

It implemented filtering to make sure water is free from larvae, and the organization employed community members to ensure infected people were not going near any water sources. When reported cases do occur, the center prevents the infection from spreading by keeping close watch on outbreaks.

Today the end is near, and Carter is close to reaching the goal he set three decades ago. Experts are hopeful that there will soon come a time when reports of infection come to a complete stop. Once this happens, Guinea worm would be the first parasitic disease that has ever been eradicated — an amazing public health feat for the 21st century.