It has been one full year since polio was detected anywhere in Africa, a significant milestone in global health that has left health experts around the world quietly celebrating.
The last African case of polio was detected in Somalia on Aug. 11, 2014, the final sign of an outbreak with its roots in Nigeria — the one country where the virus had never been eradicated, even temporarily. But the last case in Nigeria was recorded July 24, 2014.
Africa has never gone so long without a case of polio. But in an indication of how nervous experts still are that the disease may resurge, even the announcement from the Global Polio Eradication Initiative was tentatively headlined “Is Africa Polio-Free?”
“This is a big success, but it’s still fragile,” said Dr. Hamid Jafari, the initiative’s World Health Organization (WHO) director. “There’s always a worry that there could be an undetected case in a population you’re not reaching.”
Reaching the milestone is a testament to the persistence, deep pockets and adaptability of the eradication initiative, which is led by the WHO, the Centers for Disease Control and Prevention, the United Nations Fund for Children, Rotary International, the Bill & Melinda Gates Foundation and the United Nations Foundation.
When the global polio-eradication drive began in 1988, more than 350,000 children around the world were paralyzed by the virus each year. Last year, only 359 were.
The case count has been below 2,000 annually since 2001, and eradication efforts now cost about $1 billion a year. But to the frustration of epidemiologists, the virus is a master of the cross-border jailbreak. Thirty-four cases have been found this year, all in Pakistan or Afghanistan, the last place in which the virus is known to persist.
Many scientists now say a worldwide victory over polio is in sight.
“This puts a lot of pressure on Pakistan to do better,” said Dr. Elias Durry, who leads the WHO’s effort in that country and has fought polio in six others, including Somalia and Nigeria.
Even assuming there are no more cases, Africa will not be officially declared polio-free for another two years. The WHO requires three case-free years because surveillance is difficult in a continent of isolated villages and nomadic herders.
Nigeria marked its year without polio July 25 with a modest tree-planting ceremony at which the new president, Muhammadu Buhari, was photographed putting vaccine drops into the mouth of his infant granddaughter.
It was subdued because the campaign “did not want to send out the wrong message to political officeholders and donors that polio has been eradicated,” said Dr. Faisal Shuaib, a health-ministry official who helped lead both the country’s polio-eradication efforts and last year’s Ebola response.
Vaccination and surveillance efforts need to continue, he and other experts emphasized.