Bill Gates: Last polio case in 2017?

The billionaire Bill Gates - who has invested much of his money into global health initiatives - says the world could see the last case of polio in 2017.

Poplio is a highly infectious disease caused by a virus and it invades the nervous system and can cause total paralysis in a matter of hours. It mainly affects children under 5 and can prove fatal. It's thought that Pakistan and Afghanistan are the only countries yet to be polio-free.

Mr Gates says international co-operation can wipe out polio - and be used to fight other health emergencies.

(Picture - A Pakistani health worker administers polio drops to a child during a polio vaccination campaign in Karachi. Credit: Rizwan Tabassum/AFP/Getty Images)