The infection culminates in worms emerging from the sufferer's skin
Guinea worm disease may be eliminated within two years, former US president and anti-disease campaigner Jimmy Carter has said.
It would be only the second time in human history, after smallpox, that a disease had been completely wiped out.
Mr Carter says infections of the painful debilitating disease have dropped by 99%.
Guinea worm has been found across Africa from Mali to Ethiopia with most current cases in Sudan.
Only 4,410 cases were reported worldwide during the first ten months of this year, with 80% found in Sudan.
The Carter Center, established by the former president and his wife to help fight disease and champion voting and human rights around the world, says this is a dramatic drop from the 3.5m cases in 20 nations that were reported when the eradication campaign began in 1986.
The World Health Organisation reports that Guinea worm disease is now prevalent in only 13 countries in Africa including Sudan, Nigeria, Ghana, Burkina Faso, Niger, Togo and Ivory Coast.
Eight years ago it was completely eradicated from India.
Health experts hope that next year may see the last reported cases of the parasitic illness.
The disease is rarely fatal but may cause debilitating pain
Mr Carter also announced that the Bill and Melinda Gates Foundation had contributed $40m (£27m) toward the eradication effort, and the British government had pledged a further $15m (£10m).
Guinea worm occurs when people drink water contaminated with larvae.
Over a year, one or more of the larvae can grow to be a metre long.
Then they very slowly emerge through the skin, often causing searing, debilitating pain for months.
The disease is usually not fatal.
There is no vaccine or medicine for the parasite.
"It is a question of education," Craig Withers, operations director for the Carter Center, told the BBC.
"Our staff are having to wade through swamps, sometimes up to their necks, to reach remote villages in Southern Sudan."
Infection is prevented by filtering water and educating people how to avoid the disease.