Nigeria is celebrating after the UN health agency said polio is no longer endemic in the West African country.
The World Health Organisation announcement leaves only Pakistan and its war-torn neighbour 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 organisations.
Nigeria's main goal now is to maintain vigilance and make sure there are no new polio cases in the next two years so the WHO can declare it a polio-free country, Dr Funsho said.
"Until that happens we are not out of the woods yet," he said.
Once stigmatised as the world's polio epicentre, in late July Nigeria celebrated its first year with no reported case of the crippling disease, having overcome obstacles ranging from Islamic extremists who assassinated vaccinators to rumours that the vaccine was a plot to sterilise Muslims.
Just 20 years ago Nigeria was recording 1,000 polio cases a year - the highest in the world. The last recorded case of a child paralysed by the wild polio virus endemic in the country's impoverished and mainly Muslim north was on July 24 2014.
The WHO said Nigeria and Africa as a whole are now closer to being certified polio-free.
The agency warned that polio remains endemic in Pakistan and Afghanistan and that as long as the disease exists anywhere "it's a threat to children everywhere".