Bill Gates and his wife Melinda are to pay off a $76million debt Nigeria took out to rid its population of polio. Their extraordinary generosity will repay the loan taken out by the African nation from Japan in 2014, as it tries to eliminate the disease. Girl, 2, filmed smoking cigarette and calling people 'fa***ts' Nigeria had been due to begin repayments this year, but a spokesman for the couple confirmed their act of generosity in an email to qz.com. The billionaire Microsoft tycoon and his wife of their ‘deep concern’ in 2012 after Nigeria accounted for more than half of all polio cases worldwide. Thanks to the loan, it is now almost polio free and did not record any new cases in 2017, although experts warned the country has suffered false dawns before. Polio is a crippling, contagious infection which can invade sufferers’ brains and spinal cords, and cause paralysis.