Dracunculiasis: A parasitic disease caused by the largest parasite that plagues people and bores into their tissues -- the guinea worm Dracunculus medinensis. Dracunculiasis is also called guinea worm disease and end-of-the-road disease because it is not seen in the big cities.

Once it infects a person, the guinea worm migrates through their body. It eventually emerges from the body (through the feet in 90% of cases) causing intensely painful edema (swelling), a blister and then an ulcer. Perforation of the skin by the guinea worm, which can be 6 feet long, is accompanied by fever and nausea and vomiting. Infected persons may remain sick for some months.

The disease is gotten by drinking water contaminated with the infected intermediate hosts of the parasite, called cyclops. The full-grown guinea worm begins to migrate throughout the infected person's body within about a year after ingestion. In areas where the disease is endemic (pervasive), it typically reappears every year during the agricultural season, with farmers in particular being affected.

There are no drugs to treat the disease. Prevention of the disease is based on effective surveillance systems; the provision of safe water including appropriate water supply systems, filtering devices and the chemical treatment of water to eliminate the vector; and health education.

Dracunculiasis is the only parasitic disease that may be eradicated from the globe in the near future. Although widely distributed at the beginning of the 20th century, it is now confined to sub-Saharan Africa. The countries known to harbor the guinea worm are Benin, Burkina Faso, Central African Republic, Ethiopia, Ghana, Ivory Coast, Mali, Mauritania, Niger, Nigeria, Sudan, Togo and Uganda. Two-thirds of the world's estimated 100,000 annual cases of dracunculiasis occur in war-torn Sudan, where peace is needed before aid workers can reach affected areas, mainly in the south.

The Bill & Melinda Gates Foundation gave $28.5 million in 2000 to help eradicate dracunculiasis by teaching people to boil water or strain it through cloth filters. The effort to finish off this disease is a project of WHO, World Bank and Jimmy Carter's Foundation.