By Corinne Podger BBC science correspondent

The World Health Organisation and its partners have reported that polio is close to being eradicated from the Horn of Africa.

Another 22 million children still need to be vaccinated

The WHO says Sudan may have beaten polio altogether, with no reported cases of the disease for over a year.

However the health agency is appealing for continued funding to eradicate polio worldwide.

Two years ago, there were more than 300 cases of polio a year across Ethiopia, Somalia and Sudan.

This year, only Somalia has reported cases so far.

Mass campaigns

At a meeting of the Polio Eradication Initiative in Kenya, the initiative's director, Bruce Aylward, said that polio's days in Africa are numbered, even in countries where conflicts have ravaged domestic health systems.

Dr Aylward praised the work of thousands of health officials and volunteers, whom he said had on occasion literally dodged bullets to carry out scheduled mass immunisation campaigns.

But he said that another 22 million children have yet to be vaccinated and getting the vaccine to them will cost at least $50m.

Dr Aylward added that G8 country leaders have promised to keep the WHO on target to eradicate polio from Africa by 2005.

Now is the time, he says, for those promises made on funding to be kept.

Otherwise, he says the disease could cross borders from countries where it is still endemic and return to the Horn of Africa - undoing years of costly progress.