Guinea worm is going down. Way down.
From more than 3 million cases of Guinea worm disease a year in the 1980s, the world tally in 2016 stands at just two confirmed cases.
Both are in Chad and are believed to have been contained before they had a chance to spread. (There are also two suspected cases, one in Chad and one in Ethiopia.)
If Guinea worm is pushed into extinction, then Guinea worm disease would be just the second human disease to be eradicated after smallpox.
It's not a fatal condition but it's pretty horrible. There's a good reason the Guinea worm's nickname is "fiery serpent."
Guinea worm larvae live in fresh water. When people drink from contaminated ponds and other bodies of stagnant water, they can become infected with the parasite.
The larvae turn into worms that can grow to be up to 3 feet long. After about a year, the worm creates a blister, typically on the legs or feet, for its slow and painful exit.
When the worm first erupts, the person suffers a burning sensation and often seeks comfort by submerging the wound in a lake or a stream. The worm takes this opportunity to release a cloud of tens of thousands of larvae into the water. Other people end up drinking that larvae-laden water, which starts the cycle all over again.
There's no medication to kill the worms. The only treatment is to slowly pull or cut the worm out of the infected person's body.
Ringo Naah Sulley, the district director of Asante Akim South District Health Services, worked on Guinea worm eradication campaigns in Ghana in the late 1990s and early 2000s. He recalls how people used to extract the worms in his home village in Ghana.
"They have to put a knife in fire until it's red hot," he says.
"Then they would incise it [the blister]. Usually the pus would open and the Guinea worm emerged. Sometimes the Guinea worm is even cut into pieces."
The other common extraction method was to twist the worm around a small stick to slowly reel it out.
"It wasn't just a minor parasite. It was serious," Sulley says. "In one person about three or four worms could appear on any part of the body. You have to extract one after the other until you get all the parasites out."
Often the wounds from incising the blisters or yanking out the worms became infected.
Sulley is now with the health department in the Asante Akim South District in central Ghana. He says back in the 1990s in some remote villages, half the residents had Guinea worm. One of the reasons it spread so quickly is that people didn't realize how the worm spread.
David Agyemang, who is the now program manager for Sightsavers' Ghana office, used to worked on Ghana's national Guinea worm eradication program.
"Guinea worm has no cure," he says. "So everything was about getting people to change their behavior. Getting people to do the right things."
In the short term that means stopping people who had a worm dangling from their foot or leg from entering bodies of water for that momentary relief.
The longer-term solution is to get people access to clean drinking water.
Agyemang says education was the key in the drive against Guinea worm in Ghana, which eliminated the disease in 2010.
In Ghana, as soon as people learned how the worms spread, most would stay out of the rivers and lakes, says Agyemang. Even if their leg felt like it was on fire.
But to completely stop the cycle of transmission, you can't just rely on people doing the "right thing."
Communities posted guards at watering holes and new laws were put into place.
"You are not supposed to a water source if you have Guinea worm," Agyemang says. "People who did that were punished. So bylaws helped us a lot." Public health officials stress that anti-Guinea worm measures should not be imposed by outsiders.
That's the perspective from the Carter Center in Atlanta, which has been almost obsessively devoted to eliminating Guinea worm.
"The key thing is to engage the community," says Donald Hopkins, who's been working on the center's eradication program for decades. "Because it would be a disaster for outsiders, and by that I mean people from other countries, or even people from outside the community, to come in and demand that people do one thing or another."
He adds that it's crucial is to explain to the community that this parasite is coming from their drinking water and convince them that they have the power to stop it.
"And then let them figure out what to do," he says.
In his view, having a local plan is critical. "It's true that in some communities, the village elders got together and agreed that if anyone knowingly goes into a drinking water source with a Guinea worm coming out of their body, they will fine them a goat or something else as a way of punishment, but the important thing is that it must be the community that puts those sanctions in place."
Hopkins notes that an eradication program like this based on getting people to change is far more complex than a one-shot vaccination campaign. Yet the Guinea worm strategy — including the use of punishments in some communities — has been working.
Prior to the global eradication effort, which began in earnest in the 1990s, Guinea worm was spread all across the mid-section of Africa, parts of the Middle East and South Asia.
Last year, in a nod to just how close the world is to being Guinea worm-free, former President Jimmy Carter declared, "I'd like the last Guinea worm to die before I do."
The way things have been going, the 91-year-old might just get his wish.