Polio（小兒麻痹癥）is a disease of the muscles and the nervous system. It is caused by a virus and spreads through human waste. Health workers believe they may soon be able to end polio forever. The key to ending polio is preventing the disease in children.

There are many cases of polio in only six countries. They are Afghanistan, Egypt, India, Niger, Nigeria and Pakistan. Health ministers in these countries have agreed toimmunize（使免疫） two-hundred-fifty-million children against polio this year. To be immunized against polio, children must swallow a few drops of medicine several times while they are still young.

Polio can cause people to lose the ability to move their arms or legs or even to breathe. Some people die. But many people recover and become healthy again.

The World Health Organization estimates that there are about twenty-million people around the world who are survivors of polio. One polio survivor in Ghana wrote to VOA to say he is now a very good football player.

But W-H-O health workers say polio survivors need to understand a condition called "post polio syndrome." Between fifteen and forty years after a person has polio, new problems may appear. These problems may include being very tired and having weak or painful muscles. A person may have trouble sleeping, breathing or doing normal activities.

There is no way to cure post polio syndrome. People who have these problems may need to be less active. They may need to use special equipment like a stick for walking or do special exercises to make their muscles stronger. They should stop any activity that causes pain or tiredness after ten minutes.

There is no medicine to help these conditions. Some polio survivors may be taking medicines for other problems. Sometimes those other medicines may also cause people to become tired or weak. Polio survivors should always talk to a health care worker or doctor before starting or stopping any medicine that might increase their chances of getting post polio syndrome.

Experts say the best way to prevent post polio syndrome is to stay healthy. This means eating healthy food, not becoming too fat, not smoking and not drinking too many alcoholic drinks.

This VOA Special English Health Report was written by Karen Leggett.