This is Shep O'Neal with the VOA Special English Development Report.

A new kind of vaccine is being used to stop the spread of polio. World health officials say the vaccine is an important tool for the final part of the campaign to end the disease.

Experts met in Geneva, Switzerland, earlier this month to discuss the progress. They say polio could be gone within six months everywhere except Nigeria, which has the most new cases. The experts say at least another year of work is needed there.

Doctor Steven Cochi is with the United States Centers for Disease Control and Prevention. He says, "There is no reason why polio should continue to exist anywhere in the world after next year."

Until now, the vaccine used to prevent polio has combined three different medicines. That is because there are three different polio viruses. But only two of them still exist: type one and type three. Type three exists in parts of Nigeria, Afghanistan and India. Type one is more common.

The recently developed vaccine is known as monovalent oral polio vaccine. It protects only against the type one virus. World health officials say it appears to work faster than existing vaccines. They say it should now be used worldwide.

These officials say the new vaccine appears to have stopped the spread of polio in Egypt and most parts of India. Children in Yemen received the vaccine three times this year after a new outbreak there. Health officials say the number of new cases is dropping quickly now.

In a separate development, several children in an Amish community in the American state of Minnesota have polio. The Amish are a small religious group that does not believe in vaccinations. Now some parents have decided to vaccinate their children.

These are the first known polio cases in the United States in five years. State health officials said the infected children did not show signs of paralytic polio. They say the general public is not at risk because most children have been vaccinated.

Polio affects mostly children under five years old. It spreads through human waste. The virus attacks nerve cells. About one out of two hundred cases leads to permanent paralysis. Usually the victims cannot move their legs. But some of them die. There is no cure for polio.

This VOA Special English Development Report was written by Karen Leggett. Our reports are online at WWW.51VOA.COM. I'm Shep O'Neal.