Nigeria marked three years free of endemic wild polio on Wednesday, with health officials saying the nation’s progress in fighting the crippling viral disease could result in the whole of Africa being declared polio-free early next year.

The three-year milestone sets in motion a continent-wide process to ensure that all 47 countries of the World Health Organisation’s African region have eradicated the virus, the officials said.

Africa’s last case of wild polio was recorded in Nigeria’s Borno State in August 2016.

“We are confident that soon we will be trumpeting the certification that countries have, once and for all, kicked polio out of Africa,” the WHO’s regional director for Africa, Matshidiso Moeti, told reporters in a telebriefing.

Faisal Shuaib, who leads Nigeria’s National Primary Health Care Development Agency cautioned that the milestone was “one which we must delicately manage with cautious euphoria”.

Polio is a viral infection that attacks the nervous system and can cause irreversible paralysis within hours. Children under five are the most vulnerable, but people can be fully protected with preventative vaccines.

To keep the virus at bay and eventually wipe it out altogether, population immunisation coverage rates must be high and constant surveillance is crucial.

Wild polio remains endemic in Afghanistan and Pakistan, but case numbers worldwide have been reduced largely because of intense national and regional immunisation for babies and children.

At a briefing in Nigeria’s capital Abuja, Clement Peter, the WHO’s country representative, said the next six months would be “most critical” to whether Africa can be declared polio-free.

“As long as polio virus still exists in any part of the world – as it currently does in Afghanistan and Pakistan – all children are at risk. Therefore we must maintain the momentum,” he said.

Latest Global Polio Eradication Initiative (GPEI) figures show that there have been a total of 65 cases of wild polio worldwide so far in 2019 – 53 in Pakistan and 12 in Afghanistan.

According to Reuters, the GPEI, which is backed by the WHO, Rotary International and others, began its push to wipe out polio in 1988, when the disease was endemic in 125 countries and was paralysing almost 1,000 children a day globally. Since then, there has been at least a 99 percent reduction in cases.

The WHO’s Peter said Nigeria would submit its final country data in March 2020, and “if the data confirms zero cases, the entire WHO (Africa) region could receive wild polio-free certification as soon as mid-2020.”