In 2009, nearly half of the world's new polio cases were in India. The disease which can cause paralysis and death is highly infectious, but by January last year, thanks to a concerted vaccination programme, the country had gone three years without a single case of the virus. It was officially "polio-free".
This immense achievement involved many people, including 2 million vaccinators fanning out across the vast country, but was due in no small part to the determination of the Bill and Melinda Gates Foundation, whose resources helped make those vaccinations possible. Gates himself is now betting on eradicating polio entirely from the world by 2018 – and who would bet against him?