Millions had this disease in the 80s. Jimmy Carter's goal to end it now in sight.

Fans of President Jimmy Carter say one of his lifetime goals is coming close to fruition. The 99-year-old, who has been in hospice care for more than a year, rallied during his vibrant post-presidential career to eradicate Guinea worm disease worldwide.

Over several decades, the former president, who turns 100 in two months, fought to end the disease that causes chronic pain and disabilities. The world has inched closer to vanquishing Guinea worm , a parasite that people and animals contract from contaminated water.

Public health programs in targeted regions have dedicated vast resources and made remarkable headway toward that goal. Just one human case of Guinea worm disease has been reported worldwide this year. At this time last year, three people became sick from it. That stands in stark contrast to the 3.5 million people who became ill in 1986.

Eradication, a taxing and years-long endeavor, has involved a joint effort between global health experts and local officials in remote African villages. The World Health Organization says Guinea worm disease is "on the verge of eradication" now that 200 countries have been certified as free from the painful disease whose symptoms include white worms bursting out of people's skin. But the fight isn't over.

“A guinea worm anywhere is a guinea worm everywhere,” Adam Weiss, director of the Carter Center ’s Guinea worm eradication program, told USA TODAY. “It has that potential to just keep transmitting back to humans.”

What is eradication?

Aside from smallpox , a virus that has a vaccine, no disease has been fully eradicated in humans. Polio, another virus with a vaccine, has nearly been eradicated, although it lurks in Afghanistan, India and evidence of the virus has recently been found in Gaza's wastewater amid Israel’s catastrophic offensive in the Palestinian territory following the Oct. 7 terrorist attacks by Hamas militants. There is no vaccine for Guinea worm disease.

Eradication is achieved when no people and animals are infected globally for three consecutive years, said Dr. Sharon Roy, a medical epidemiologist at the Centers for Disease Control and Prevention’s parasitic diseases and malaria division. Chad, Angola, Ethiopia, Mali, South Sudan and Sudan continue to report cases of animals being infected by Guinea worm disease. However, this year's single case is significant, given the logarithmic drop in human cases.

The near total reduction in cases now, Roy said in a statement, “is a testimony to President Carter’s bold vision and steadfast commitment to champion the eradication of this neglected tropical disease” that has no drug to treat it, nor a vaccine.

International health officials have heralded the Carter Center and its partners' joint response to Guinea worm for creating localized health responses that have helped impoverished and under-resourced countries by offering community education, investigations of the disease progression, specially designed drinking straws that filter water, and access to larvicide.

How does it spread?

Guinea worm takes refuge in a dwindling number of remote villages. It spreads when people drink unfiltered water that contains larvae.

People don’t develop symptoms of the parasite until about a year after they've ingested it. At that point, female white worms up to 3 feet long burst from people’s skin, usually from their legs or feet. People develop, fever, swelling and pain in the area where a worm is trying to exit their body and a worm erupts through a burning blister. This can result in infected wounds.

When the female worm escapes a person or animal's body, it lays thousands of larvae. The larvae become submerged in the water, repeating the Guinea worm's lifecycle.

While the disease is not fatal, it has had devastating effects on village communities and economies historically, preventing children from going to school and adults from tending to crops or cattle. For this reason, it's been called the “disease of the empty granary." And because of the pain the worms cause, it's also known as the "fiery serpent."

Crown emojis, memes celebrating Jimmy Carter

In recent posts on X , users highlighted recent data from the Carter Center showing there were zero reported cases through March 31 of this year, compared with 14 cases in 2023. Scores of posts, by Guinea worm insiders and casual observers, championed Carter with crown emojis and memes , lauding his decades-long effort to curb the debilitating disease.

Several public health callouts reminded people unfamiliar with the disease how devastating it once was.

“If you’ve never seen it or heard of Guinea worm disease, here’s why it matters. The worms can grow up to 3 ft long under skin & cause severely painful blisters via which worms emerge,” Dr. Tatiana Prowell, an associate professor of oncology at Johns Hopkins University School of Medicine, wrote in a post . “It caused great suffering & disability.”

The disease appeared to be waning until a case showed up this spring. In May, one person fell ill in Chad.

Guinea worm cases usually appear in the spring, during the rainy season. People typically get infected, months or a year before the worms emerge.

As human cases declined in the region, officials became worried about a lingering source of transmission. Dogs were not believed to be carriers of the disease, but recent evidence from Chad has shown worms can thrive in domesticated dogs and then spread disease in villages.

'Never going to be able to see it'

To tackle disease transmission between animals and humans, U.S. public health officials use the “ one health ” model, which can mean educating communities on the role dogs play in spreading diseases that are also harmful to people. Weiss, of the Carter Center, said improved surveillance of domesticated and wild animals will be necessary to eradicate guinea worm disease, which he said is still feasible.

The number of infected animals has significantly declined. In 2019, 2,000 animals were infected with the disease, Weiss said. The number this year has dropped to 162.

Jordan Schermerhorn, an infectious disease epidemiologist who has worked in rural Africa, said trying to prove a disease doesn’t exist is difficult. She compared it to trying to prove that a 6-year-old child doesn’t have an imaginary friend.

“You’re never going to be able to see it,” she said, which makes it complicated to know you've eradicated it. Keeping tabs on infections is even trickier than trying to track dogs or other animals, she added.

Yet progress toward ending the disease is evident. In the year President Carter could become a centenarian, international officials tracked just one person in the world with the parasite. The search for the last white worm continues in the world’s most remote villages. His birthday is Oct. 1.

This article originally appeared on USA TODAY: Millions had this disease in the 80s. Jimmy Carter's goal to end it now in sight.