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.
AUDIE CORNISH, HOST:
The world is on the verge of a medical milestone. Guinea worm is on the brink of extinction. So far this year, there have been only two cases of the disease detected in the world. That's down from several million cases a year in the 1980s. In a moment, we'll hear from former President Jimmy Carter. He led efforts to eliminate Guinea worm. But first, here's NPR's Jason Beaubien.
JASON BEAUBIEN, BYLINE: I have to start by saying that Guinea worms are disgusting. If you're not familiar with them, they're like this long piece of spaghetti that erupts from under a person's skin. And it's usually on the foot or their leg, and they can be up to 3 feet long. The only treatment is to slowly pull or cut them out with a knife.
RINGO NAAH SULLEY: You have to put a knife in fire - fire it until it's red-hot.
BEAUBIEN: Ringo Naah Sulley remembers how in his home village in Ghana they used to cut open the Guinea worm blisters.
SULLEY: And the Guinea worm - it mate. Sometimes the Guinea worms even cut into pieces.
BEAUBIEN: The other common extraction method was to twist the worm around a small stick and slowly reel it out. Sulley worked on Guinea worm eradication in Ghana in the 1990s and early 2000s when Ghana had one of the highest number of cases in the world. He says in some remote villages you'd find hundreds of people infected with the worm.
SULLEY: It wasn't just a minor parasite. It was serious. In one person, about three, four worms can appear in - on any part of the body, and you have to extract one after the other until you get all the parasites out.
BEAUBIEN: And getting the worms out is painful. Guinea worm is known as the fiery serpent because of the burning sensation as it emerges. The person often tries to cool the wound by submerging it in a pond. The worm takes this opportunity to release a cloud of tens of thousands of larvae into the water. Other people eventually end up drinking that larvae-laden water, which in turn produces more worms inside more people.
David Agyemang who worked on Ghana's national guinea worm eradication program says the campaign wasn't built around a vaccine or a miracle drug.
DAVID AGYEMANG: Everything is about people - getting people to change their behavior, getting people to do the right thing.
BEAUBIEN: Ghana got rid of Guinea worm back in 2010. Now this year, there've only been two confirmed cases, and those were in Chad. And there's one suspect case in Ethiopia. Agyemang says the key in Ghana was to stop people with dangling worms from entering bodies of water, even if their legs felt like they were on fire. Some communities took forceful measures, posting guards at watering holes and handing out stiff fines.
Donald Hopkins is with the Global Guinea Worm Eradication program at the Carter Center in Atlanta. He says punishing people in the pursuit of public health is a tricky business and it can't come from outsiders.
DONALD HOPKINS: It's true. And in some communities, the eldest members have gotten together, and they have agreed that if anybody knowingly goes into a drinking water source with a Guinea worm coming out of their body, they will fine them a goat or something as a way of punishment. But the important thing is that it must be the community that puts those kinds of sanctions in place.
BEAUBIEN: Hopkins notes that a campaign centered around behavior change is a lot harder than just giving people a vaccine. But it's worked across a wide swath of Africa and South Asia. The Carter Center is now one of the driving forces behind Guinea worm eradication globally. Last year, former President Jimmy Carter declared I'd like the last Guinea worm to die before I do. And the way things have been going, the 91 year old might just get his wish. Jason Beaubien, NPR News. Transcript provided by NPR, Copyright NPR.