The viral polio disease has over the years crippled hundreds of thousands of children in Africa and other parts of the world.
But on August 25, some four years after Africa’s last case was recorded in northern Nigeria, the continent was declared free of wild polio. Still, vaccine-derived strains of the virus remain in more than a dozen African countries.
Pakistan and Afghanistan are the only two countries in the world where the debilitating virus remains endemic.
Polio is transmitted from person to person, mainly through a faecal-oral route or, less frequently, through contaminated water…