The wild form of the debilitating and sometimes deadly poliovirus has been officially wiped out in Africa.
Polio usually affects children under five, with death occurring when breathing muscles become paralysed. While there is no known cure for the disease, the polio vaccine offers life-long protection.
The last African country to have eradicated wild polio is Nigeria, which less than ten years ago had more than half of all cases worldwide.
A huge vaccination effort in Nigeria successfully reached remote places, including those threatened by militant violence. Some health workers lost their lives delivering vaccines in these areas.
Today, over 95% of the African population has received the polio vaccine and the very few remaining cases of the virus are those derived from the vaccine itself, which spreads in under-immunised communities.