Lagos - The World Health Organisation said on Friday 116 million children are to receive polio vaccines in 13 countries in west and central Africa as part of efforts to eradicate the disease on the continent."The synchronised vaccination campaign, one of the largest of its kind ever implemented in Africa, is part of urgent measures to permanently stop polio on the continent," the WHO said.The programme will see all children under the age of five in 13 countries immunised from Saturday "in a coordinated effort to raise childhood immunity to polio," it added.The countries are Benin, Cameroon, Central African Republic, Chad, Ivory Coast, Democratic Republic of Congo, Guinea, Liberia, Mali, Mauritania, Niger, Nigeria and Sierra Leone. Once a worldwide scourge, polio is still endemic in three countries - Nigeria, Afghanistan and Pakistan. This year, the WHO has recorded four cases of polio - two each in Pakistan and Afghanistan. Last year, there were 37 cases globally.The four-day campaign in Africa by 190 000 vaccinators is part of the response to the discovery of three cases of polio in the insurgency-wracked state of Borno in northeast Nigeria last year.Before then, the west African country had not reported a case of polio in two years and was on track to be certified free of the virus this year. Rod Curtis, from the UN children's fund Unicef in Borno, told AFP another campaign would take place at the end of April in the countries around Lake Chad.Lake Chad forms the border between Nigeria, Niger, Chad and Cameroon, which have all been affected by Boko Haram's Islamist insurgency. "It's funded by international donors, local governments and the government of Japan who spent $33m specifically to support this campaign," he said. Polio is a highly infectious viral disease which mainly affects young children and can result in permanent paralysis. There is no cure and it can only be prevented through immunisation. Matshidiso Moeti, WHO regional director for Africa, said South Africa's former president Nelson Mandela launched a campaign 20 years ago to "Kick Polio Out of Africa"."At that time, every single country on the continent was endemic to polio, and every year, more than 75 000 children were paralysed for life by this terrible disease," said Moeti. "Thanks to the dedication of governments, communities, parents and health workers, this disease is now beaten back to this final reservoir." Unicef's regional director for west and central Africa, Marie-Pierre Poirier, said she was hopeful polio could be wiped out with the help of African leaders."Polio eradication will be an unparalleled victory, which will not only save all future generations of children from the grip of a disease that is entirely preventable, but will show the world what Africa can do when it unites behind a common goal," she said.