The UN's World Health Organization (WHO) on Tuesday declared that Africa was now free of poliovirus, a landmark in a decades-long campaign to eradicate the notorious disease around the world.

"Today is a historic day for Africa," said Professor Rose Gana Fomban Leke, whose commission certified that no cases had occurred on the continent for the past four years, the threshold for eradication in the wild.

Poliovirus now joins smallpox in the list of viruses that have been wiped out in Africa, the WHO said.