When a disease achieves “celebrity status” – garnering attention and resources – there is bound to be resentment among those working on other conditions that have been overlooked. HIV/Aids came to global notice in the 1980s and 1990s and sucked in funds on a scale hitherto undreamt of in the developing world.

Meanwhile, malaria, tuberculosis and, the biggest child killer of all, diarrhoeal disease were neglected, opening up sharp divisions in the aid world.

Today the world is facing a similar situation with polio. Thanks to eradication efforts over the past 25 years, the total of cases worldwide has been reduced by 99 per cent, to just 222 last year. For the generation that remembers the outbreaks in 1950s Britain, Europe and the US, when thousands of children died or were left paralysed and panic gripped parents, that is an astonishing achievement.

But the work is not cheap  – $9bn has been spent so far – with an estimated $5.5bn required to root out the last couple of hundred cases, equivalent to $25m for each case. Health workers running routine immunisation programmes for measles, diphtheria and other lethal diseases complain that all the focus has been on polio. Local people protest, during the frequent polio immunisation days, telling health workers bitterly: “You only give us polio drops, but we have so many other problems.”

There are no easy answers. Even if the Global Polio Eradication Initiative, backed by governments and health organisations around the world, succeeds in banishing the virus completely – and that is by no means certain – more lives might have been saved by, for example, programmes to improve sewage systems.

That might be a practical suggestion, but it would be churlish. Banishing polio will protect future generations for all time, and it is to the great credit of Bill Gates that he is committing some of his fortune to the task. Success will be far harder to achieve than eradicating smallpox, the only other disease eliminated in the past century.  But if it can be done, it would demonstrate, as Mr  Gates says, what is best about humanity.