Rotarians around the globe have been celebrating our 30-year-long fight to eradicate polio, and for several years it apparently had been restricted to just two countries whereas it once was common in all parts of the world.

Sadly, on Thursday the World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) announced that two children have been diagnosed with polio paralysis in Nigeria. The irony is that the day of the announcement would have marked two years since the last reported case of polio on the African continent.

The development is a major setback to the international effort spearheaded by Rotary International (RI) that had sequestered polio into only Pakistan and Afghanistan. Even there, only 19 cases have been found this year, strong evidence that the immunization effort was nearing its goal of preventing all cases.

Polio, while incurable, is preventable with ongoing immunization programs. It is highly infectious and, if not prevented, causes paralysis, permanently twisted limbs, respiratory distress, and even death. In some cases polio survivors develop secondary health problems in their adult years that can be worse than the original onset.

People not familiar with the specifics of polio can find a quick but thorough explanation by clicking here to go to the SRC website page titled “What is polio?”

RI, WHO, and the CDC now are quickly preparing multiple emergency immunization efforts for millions of children in Borno state, Nigeria’s most northeastern province that shares land borders with the nations of Cameroon and Niger and a water border with Chad.

“This is a setback, definitely, these two cases that have been detected after two years of what we thought was a Nigeria free from polio,” Dr. Michel Zaffran, director of WHO’s polio eradication program, said in a briefing Friday morning. “This is a true disappointment.”

Zaffran told media there probably will have to be six separate rounds of vaccination covering northern Nigeria and its neighbors. The first, in Borno, should begin in a few days.

“This is a major response to what we consider a major threat to the polio eradication initiative,” he said.

According to the National Geographic news service, WHO said genetic analysis of the virus from the two children and their families, who live in different parts of Borno state, “reveals that it is most like a strain collected in Borno in 2011. That implies polio has never been eliminated from the region but instead was circulating silently, even though Nigeria had not detected any polio cases anywhere in the country since July 2014. The brutal math of polio epidemiology — experts consider that only one in every 200 cases is detected — makes it likely that polio could be present throughout the area.”

Borno is the home territory of Boko Haram, the fundamentalist terrorist militia that may be best known for kidnapping 276 schoolgirls from the town of Chibok. Boko Haram has conducted a sustained campaign of bombings and slaughters estimated to have killed 20,000 people in seven years, and has destabilized all of northeastern Nigeria.

Nigeria’s health minister, Isaac Adewole, said in a statement that the cases were found because government military action recently took back portions of Borno state from the militants, allowing “strengthened surveillance.”