This is the VOA Special English Development Report.

Guinea worm disease usually does not kill, but it is extremely painful. It prevents people from caring for their farms, their homes and sometimes even themselves.

Guinea worms can grow up to one meter long

In nineteen eighty-six, an estimated three and one-half million people in Africa and Asia suffered from Guinea worm disease. There were cases in more than twenty countries.

Today, Guinea worm still exists. But in two thousand seven, fewer than ten thousand cases were reported in five countries.

International organizations made the difference. They worked to increase activism and donations to the Global Dracunculiasis Eradication Campaign. That is the technical name for Guinea worm disease. Local governments provided support for services.

The Carter Center in the United States led the efforts. The World Health Organization and UNICEF, the United Nations Children's Fund, also played central parts. So did the United States Centers for Disease Control and Prevention.

The C.D.C. says Guinea worm no longer strikes in Asia. Most remaining cases are in Sudan and Ghana. The other countries affected are Mali, Niger and Nigeria. All five are working to stop the disease.

The disease affects poor communities that do not have safe water to drink.

Guinea worms are parasites -- organisms that live in other organisms. The parasites enter the body when a person drinks water containing water fleas infected with Guinea worm larvae, the young form of the worm. "Water fleas" are not insects but copepods, a crustacean like lobsters and crabs but extremely small.

Almost a year passes without signs of the disease. But during that time the worm develops inside the person's body. Some reach lengths of one meter.

Then the worm makes its way toward the skin surface. A blister forms, usually on the legs or feet.

The person suffers greatly when the worm cuts through the skin and leaves the body. And it is not unusual for an infected person to have more than one Guinea worm.

The international campaign has worked to help communities improve their supplies of drinking water. For example, villagers have been taught ways to keep water clean and to take steps like running water through cloth to reduce the risk of infection.

There is no vaccine against Guinea worm and no totally effective treatment. But the disease can be managed to reduce pain and infection.

And that's the VOA Special English Development Report, written by Jerilyn Watson.