Guinea worm disease, a debilitating parasitic infection that has ravaged African and Asian populations since antiquity, may be on the verge of being eradicated, says Jimmy Carter. The former president has helped lead the global effort to fight Dracunculiasis, or Guinea worm disease, through his work with the Carter Center, a foundation he and his wife, Rosalind, established for fighting disease and promoting human rights. Speaking at a recent press conference, Carter lauded the Bill and Melinda Gates Foundation for pledging $40 million to carry out the final stages of the eradication campaign. He also predicted Guinea worm disease would be stamped from human populations within two years, making it the second disease humankind has eliminated—the first being smallpox, which met its demise during Carter's presidency.

Guinea worm disease afflicts the poorest of the poor, those living in areas with poor sanitation and minimal access to primary health care. Often these populations are burdened by a variety of other devastating diseases, including malaria. The culprit in Guinea worm disease is a roundworm parasite called Dracunculus medinensis, whose larvae dwell in microscopic water fleas. People contract the disease by drinking unfiltered water harboring larvae-infected fleas. Once swallowed and passed through the stomach, these larvae burrow into the intestinal tissue and reproduce. The offspring are worms that migrate through the body tissues on a slow journey toward the skin. By the time the worm completes its trek (about one year later), it resembles a giant spaghetti noodle measuring as long as two or three feet. Victims of the disease sometimes see the worm moving beneath their skin as it prepares to break the surface. The worm eventually pushes its way out of the skin, causing an excruciating burning sensation.

One of the only ways to relieve this pain is by dipping the infected area in the local water source. Sadly, this only helps the worm perpetuate its life cycle. The worm releases millions of larvae into the water, which are then eaten by water fleas, the very critters responsible for transmitting the worm to the person in the first place.

Efforts to rid populations of Guinea worm disease have been hugely successful. Working with local governments and international health organizations, the Carter Center has helped slash the number of infections from 3.5 million in 1986 to fewer than 5,000 cases today (a 99.7 percent  decline). There once were 20 African and Asian countries afflicted by the Guinea worm. Today there are only six: Sudan, Ghana, Mali, Ethiopia, Niger, and Nigeria.

How does Guinea worm disease impact human health and what needs to be done to  stamp it out? We asked the Carter Center's Guinea worm disease expert Kelly Callahan, who has been involved in eradication efforts for 12 years.

How does Guinea worm disease manifest itself?
For the first nine-to-12 months, you don't know you have Guinea worm disease. The [first] symptoms are malaria-like: fever, nausea, chills, and absolutely no energy. [A few weeks later], the worm forms a large burning skin ulcer, causing intense, localized pain. As soon as the ulcer forms, you can barely move that part of the body. In the middle of the ulcer, a blister forms where the worm emerges. It takes at least 10 days for the worm to exit. It’s agonizing. There is no way you can walk if it's on the leg or the foot. You can have multiple worms coming out different places. You can wrap a stick around the worm and pull the worm every other day until it resists, pull it and coax it out. But if a worm pulls back inside the body, it can calcify, cut off blood supply, and cause paralysis.

Is there a treatment for Guinea worm disease?
There is no treatment.

How do you prevent it?
The most proven method is teaching people to filter water. The pipe filter, which looks and acts like a straw, is portable and easy to use. There is a filter cloth on the end of the straw far from the mouth [that sieves out the fleas carrying the Guinea worm larvae].

Other methods include teaching people to stay out of public water. Anyone who has an emergent guinea worm should not go into the water [because  he or she is shedding millions of Guinea worm larvae].

What kind of obstacles might interfere with this final push toward eradication?
The biggest problem is access. It is very difficult to access southern Sudan and northern Mali where sometimes there are no paved roads. [It's not easy] getting to some communities that have Guinea worm disease on regular visits.

Ten years ago, many health experts were confident that polio would be eradicated by now. How is guinea worm disease different?
There are several reasons Guinea worm disease is favored for eradication. First, it has a seasonal duration; we know when Guinea worm is going to come out of the body. When the rains start to come the worms begin emerging. People contract the disease during the rainy season and emit worms during the rainy season. (Polio, in contrast, is transmitted year round).

Second, preventing Guinea worm disease is community-based and community oriented. The community takes ownership; the people have carried out the eradication effort. (Polio prevention campaigns, on the other hand, are often carried out by visiting health workers administering vaccines).

Third, Guinea worm disease is easy to diagnose; the worm is coming out of the body. [whereas many polio infections are asymptomatic and thus virtually invisible to health workers].