Nigeria on Saturday celebrated the announcement by the U.N. health agency that polio is no longer endemic in the West African country. 

The news of Nigeria's progress, made by the World Health Organization on late Friday, leaves only Pakistan and its war-battered neighbor Afghanistan as countries where the disease is prevalent. Polio which can cause life-long paralysis can be prevented with a simple vaccination.

"It's a great moment for Nigeria," Dr. Tunji Funsho, chairman of Rotary International's anti-polio campaign in Nigeria, told The Associated Press. "We should celebrate but with a caveat that we should not let our guard down." He attributed the success to teamwork between government and non-governmental health organizations.

Nigeria's main goal now is maintain vigilance to make sure that Nigeria has no new polio cases in the next two years so that the WHO can declare Nigeria a polio-free country, Dr. Funsho said. "Until that happens we are not out of the woods yet," he said.

Once stigmatized as the world's polio epicenter, Nigeria in late July celebrated its first year with no reported case of the crippling disease, having overcome obstacles ranging from Islamic extremists who assassinated vaccinators to rumors the vaccine was a plot to sterilize Muslims.

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Just 20 years ago this West African nation was recording 1,000 polio cases a year - the highest in the world. The last recorded case of a child paralyzed by the wild polio virus endemic in Nigeria's impoverished and mainly Muslim north was on July 24, 2014.

WHO said Nigeria and Africa as a whole are now closer to being certified polio-free.

The agency warned polio remains endemic in Pakistan and Afghanistan and that as long as the disease exists anywhere "it's a threat to children everywhere."