JUBA, Sudan (Reuters) - Rheumy-eyed Chief Joseph Lokoi has lived through two civil wars in south Sudan, but the scars covering his body are not the relics of battle.
Each one marks the spot where a Guinea worm -- a spaghetti-like waterborne parasite up to one meter (3 feet) long -- pushed out of his skin.
After living inside its host for up to 14 months, the long worm, often known as the "fiery serpent," releases chemicals to soften the flesh, making a blistering, pus-filled wound. It then pushes out so it can deposit around a million larvae.
"The pain is great," said Lokoi, who lives in Sudan's dry Eastern Equatoria State, where most men carry a gun and where deadly cattle raids are common.
Burning pain sends many victims into the nearest available water for relief. For Lokoi's Toposa tribe, this is often one of the small stagnant hand-dug rainwater ponds or shallow wells the whole community depends on.
The Guinea worm spews a cloud of larvae into the water on contact and dies. Unless it is boiled or filtered, the water is likely to infect those who drink it.
Sudan is home to four-fifths of the world's cases of Guinea worm: a painful and soul-destroying yearly fixture that often afflicts people during the rainy season. But now, there is fresh hope the parasite can finally be eradicated.
Pastoralist communities like Lokoi's have not yet seen many health or education benefits from a 2005 peace deal that ended more than two decades of war between the northern government in Khartoum and southern rebels.
But peace and stability have improved access to some isolated areas -- although the western Darfur region is still gripped by its own rebellion -- and this has helped those fighting to rid Africa's largest country of Guinea worm.
The semi-autonomous southern government and the U.S. Carter Center, an aid group set up by former U.S. President Jimmy Carter, aim to eliminate Guinea worm from Sudan by 2009 as part of their goal of ridding the world of the disease by then.
This would be the first global eradication since smallpox was wiped out in 1977, and the first without vaccines or medicines.
"There is no silver bullet, no vaccine. When we eradicate Guinea worm in the world, it will be because people changed their behavior," said Steven Becknell, who heads south Sudan's Carter Center office.
"If you can keep everyone who has Guinea worm out of the water for one year, then it's gone," he added.
When the Carter Center first got involved with the disease in 1986, there were 3.5 million cases worldwide.
In 2006, only 25,217 cases were recorded and just over 20,000 of those were in Sudan. Ghana recorded around 4,000 cases that year, and the parasite, also known as dracunculiasis, is also holding on in Mali, Nigeria and Niger.
Since then, there has been dramatic improvement in Sudan, which registered only 5,815 cases in 2007. The end of the war meant the areas affected became accessible to a revamped government-led project distributing vital barriers against the disease. These include more than 1 million pipe filters and nearly half a million cloth filters.
The Carter Center distributes cloth filters and plastic drinking pipes with gauze at one end to block the larvae. These pipes are often seen hanging alongside beads around the necks of boys from the Toposa tribe.
Ponds are also treated with chemicals, and other agencies have drilled boreholes to provide clean drinking water. Over 25,500 volunteers monitor around 22,000 villages, counting worms that pop out of the skin, and doing "case management."
This means stopping infected people from going into the water, and pulling worms out of victims' bodies.
Volunteers use tools like a forked toothpick, which they roll between finger and thumb, twisting the worm around it. Often the worm is wrapped around the victim's muscles, making the process extremely painful.
"(It can take) sometimes minutes and sometimes many, many days," Field Officer Julias Lotubae explained.
The Carter Center says many believe this extraction process may be the origin of the symbol commonly associated with the medical profession: the snake-like animal wrapped around a stick.
Eradicating the disease would bring both social and economic gains, as well as easing individuals' suffering.
The Carter Center estimates rice farmers in southeastern Nigeria lost $20 million in one year because of outbreaks of Guinea worm which incapacitated workers.
The worm itself rarely kills, although secondary infections from the wound can be deadly. But the parasite drains energy and nutrients and hampers movement.
"People cannot cultivate, children cannot go to school," said Makoy Samuel Yibi, director of the southern government-led project to eradicate the disease.
Sometimes seen as a curse of the ancestors, the disease affects men and women almost equally, especially those aged between 16 and 35 years, the most productive age group.
Like Lokoi, many people get the worms every year.
"I have seen someone with 16 worms emerging at one time," Yibi said.
Guinea worms usually break out of the flesh in the legs or feet, but Lokoi has seen them growing in a person's head and emerging out of sexual organs and eyes.
In the red dust of Eastern Equatoria State, Toposa Kumoliang, a mother of five, says not a year goes by without one of her children contracting Guinea worm.
"It makes my children restless and unable to play, helpless, it is very painful," she said, sitting on the ground, wearing colorful layered necklaces and beads around her upper arms and wrists.
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