The World Health Organization says the most infectious type of polio could be eradicated worldwide by next year, leaving only one more strain of the disease to be tackled. WHO, which began its global polio eradication campaign in 1988, says it is on track to rid the world of this crippling disease. Lisa Schlein reports for VOA from WHO headquarters in Geneva.

There are three types of wild poliovirus. Type-two polio disappeared from the world in the late 1990s. The World Health Organization is now concentrating its efforts on tackling type-one polio, the most virulent strain, before moving on to rid the world of type-three, the last remaining strain of this disease.

WHO Assistant Director-General for Health Security, David Heymann, says there is renewed optimism that this battle can be won because a new, better polio vaccine is available..

"In fact, type-one polio could be eradicated from the world some time next year we believe if activities continue, because this vaccine has been so effective in interrupting transmission in some of the major reservoirs of polio...21...and then we would remain with type three, which is also being addressed by monovalent vaccines and those vaccines have just come into use recently," said Heymann.

The monovalent oral polio vaccine uses only the attenuated strain of type-one poliovirus and only immunizes against that strain of the disease. A monovalent vaccine now has been developed that immunizes children against the type-three poliovirus.

When the World Health Organization launched its global polio eradication campaign in 1988, more than 1,000 children a day became infected with this paralytic disease. This year, only 765 cases have been reported, compared to less than 2,000 last year.

Doctor Heymann says polio remains endemic in only four countries - Nigeria, India, Pakistan and Afghanistan.

"Type-one polio is the polio that was occurring in northern Nigeria and it is the virus that spreads very easily from person to person and country to country. It spreads very rapidly," he said. "And, what happened was when Nigeria stopped vaccinating back in 2003, the virus spread to countries throughout Africa and all the way over into Indonesia and Saudi Arabia and many of these countries did not have a high enough protection rate to prevent outbreaks."

Doctor Heymann says type-one polio appears to have been wiped out in India and the country now is intensively trying to get rid of type-three polio.

Doctor Heymann says the biggest threat to polio eradication is lack of money. He says the campaign needs $250 million to carry out its immunization work next year.