Africa eradicates wild polio

Now only Afghanistan and Pakistan still have cases of wild polio, the most threatening form of the disease. The African Regional Certification Commission for Polio Eradication officially declared the continent free of the virus on Tuesday. Despite the progress, 16 African nations have recorded cases of vaccine-derived polio, a mutated form of the weakened virus from the oral polio vaccine.

How is eradication identified? The continent that once recorded 75,000 cases every year received the certification after going four years without recording a new case. The last infection occurred in 2016 in northern Nigeria, which has faced intense insurgent attacks. Dr. Matshidiso Moeti, the World Health Organization’s regional director for Africa, said eradication is the culmination of a “massive undertaking, with amazing persistence.” Wild polio is a highly infectious, waterborne virus that mostly affects children younger than 5.

Dig deeper: From the WORLD archives, read about the day I spent with a polio campaign team.