Polio Returns to Nigeria for the First Time in Years

Two children have been diagnosed with polio paralysis in Nigeria. It’s a major setback to the international effort to eradicate the disease, which health authorities thought they had sequestered into only Pakistan and Afghanistan.

The news was announced by the World Health Organization and the Centers for Disease Control and Prevention Thursday, a day that would otherwise have marked the two-year anniversary of Africa’s last case of polio. If Thursday had come and gone without any cases being discovered, that would have triggered a 12-month countdown to the entire continent’s being certified free of polio, a crucial step in the almost 30-year battle to wipe the disease from the world.

“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,” Michel Zaffran, a physician who is WHO’s director of polio eradication, said in a briefing Friday morning. “This is a true disappointment.”

Before Thursday, only 19 cases of naturally occurring polio had been found in 2016, all in Afghanistan and Pakistan, where the international effort by the WHO, CDC, and Rotary International has been concentrating eradication efforts. The partners will now have to mount multiple emergency vaccination campaigns to immunize millions of children in the area where the cases were found: Borno state, Nigeria’s most northeastern province, which shares borders with Niger and Cameroon and is across Lake Chad from Chad.

Zaffran said Friday that there will probably have to be six separate rounds of vaccination covering northern Nigeria and neighboring countries, including Chad, Cameroon, Niger, and the Central African Republic. The first, in Borno, should begin next week, he said.

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

A Silent Presence

The WHO said genetic analysis of the virus from the two children and their families, who live in different parts of Borno, 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 state is also one of Nigeria’s most unstable areas. It’s 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 that’s estimated to have killed 20,000 people in seven years, and has destabilized all of northeastern Nigeria.

It’s not unusual for internal conflict in a country to interfere with polio eradication; in Pakistan, the Taliban has persistently attacked teams of vaccinators. But, until recently, Boko Haram’s violence made parts of Borno state no-go areas even for Nigeria’s military.

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

John Vertefeuille, an epidemiologist who is the CDC’s polio eradication branch chief and formerly ran the agency’s Nigeria office, said the part of the country where the cases were found poses unique challenges for reaching children and keeping vaccinators safe.

“The Lake Chad region is complicated, because the lake itself grows and shrinks, and it is hard even to estimate the number of island communities—some of which are formal communities, and some of which move around following crop seasons and the water needs of their livestock,” he said.

“Then put on top of that, Boko Haram has created such a situation of insecurity that the government of Nigeria declared a national emergency for Borno and (neighboring) Yobe state that has been in place ever since. There are many instances in which Boko Haram has gone in, taken over a town, displaced the population—who had to move to an internal resettlement camp or outside the country or resettle with family or friends—and destroyed the hospitals and schools.”

Ongoing Security Challenges

Nigeria’s place in the international polio fight has been a complicated one. In 2003, religious leaders in north-central Kano state commanded followers to stop accepting polio vaccine, claiming the formula had been contaminated in a Western plot against Islamic children. That put a stop to vaccination in northern NIgeria for more than a year, long enough for polio not only to surge back there, but also to leak across borders and seed the disease in 14 other African countries.

Rates of vaccination remained low for years, which allowed what is called a “vaccine-derived virus”—a random mutation of the weakened vaccine strain back to the virulence of natural polio —to bloom into an epidemic in 2006.

Those political divisions were eventually healed and the country recommitted to polio eradication—to the point, Vertefeuille said, that the new cases were found because a Nigerian task force was already in the field, tracking down an alert over a possible vaccine-derived strain.

“Nigeria’s ability to respond to polio has changed dramatically from the old days,” he said. “I want to say strongly that I believe the Nigerian polio response will be able to effectively handle this.”

But the security challenge posed by Boko Haram is going to continue to make the task difficult, he warned. “It will require a lot of special effort, and linkage to the security forces and really constantly reading the data. So when there are opportunities, they are able to move in quickly and get vaccine in there and get back out if the situation changes again.”