THE major pandemic the world is facing right now is not an infectious disease, but obesity. And Scotland, which has some of he highest rates in Europe, needs urgently to tackle it.

Professor Peter Piot, a renowned microbiologist and part of the team that discovered Ebola, argues that it must be a "top priority" for the UK or the result will be “healthcare costs getting out of control”.

Piot, who is in Edinburgh today to receive the Edinburgh Medal for his contribution to science and humanity, spells out his formula for tackling the problem.

“You need to involve industry,” he said, “you need to have a real strategy, and when it comes to obesity we will need very strong leadership to reverse that trend. Because it’s going to be a major handicap for Scotland, and for other parts of Europe, if we can’t bring it under control.”

There are lessons to be learned, he explained, not only from the legislation created around smoking, but also from the battle against AIDS, in which he played a major scientific role.

Already, in the United States, Piot observed, life expectancy at birth for white men and women has gone down in the last few years. “That’s due to obesity, diabetes, alcohol and drugs. Historically that has never happened outside wartime.”

He described how, earlier this year, at Davos World Economic Forum, he presented a lecture which he ended by saying he was “now going to speak about an epidemic not caused by a microbe”. He then showed a map of the world that demonstrated how obesity was spreading like an epidemic, or contagious disease. This is not only a problem for Western developed countries. With urbanisation and the spread of Western diets, obesity and diabetes are now rising faster in low-income countries than developed nations.

Today Piot will present a lecture at the Edinburgh International Science Festival looking at epidemics and a global context, and whether the world is ready for the “ Big One” – a Spanish Flu-type of pandemic caused by a new influenza virus.

Much of what he presents is a positive story. “There has been great progress in improving health,” he explained. “We’ve never lived this long, never had it so good health-wise. The life expectancy in Scotland has improved even in the last 15 years, although the country does have the lowest life expectancy in Western Europe and the widest mortality.”

However, his concern is that we “ensure that this new epidemic of obesity and diabetes is not going to wipe out all the gains that we’ve made.” To do that, Piot said, will require “an all-encompassing, societal programme that not everybody will like because it means doing certain things less that we all like.”

Piot, a former director of UNAIDS, the United Nations programme on AIDS, said that there were things that could be learned from the battle with the viral disease.

“Both problems revolve around something that is pleasurable. In the case of HIV, it’s sex, and with obesity, it’s partly eating. What we’ve learned is that it’s not just by providing information that you have an impact. With obesity, we also need to think about why are people obese. And some of it has to do with the fact that the affordable food is not necessarily the healthy food.”

He said what was needed was “smarter research”, in everything from science, policy-making and marketing. Among those strategies he advocated was regulation on sugar content of foods, restrictions on advertising, new rules around foods sold in schools and hospitals.

He also pointed out the “two success stories” of the smoking ban and legislation around seatbelts in cars and helmets for motorbikes. “These have really reduced mortality in a big way.”

People objected at first, he continued, “But then it becomes normal. You change the norms. Think of smoking. When I was a student it was totally normal, everybody was smoking. And, actually, if you didn’t smoke, you were just not cool. Today with many youngsters it’s just not cool to smoke.”

One of the things that obesity has in common with infectious disease, he observed, is that it is linked to deprivation. “Health problems in Scotland have a lot to do with deprivation and social conditions. The same is true for epidemics – again it’s the poor that are affected more, the ones that live in slums and have less access to health care.”

Piot cited New York as an example of a city that managed to turn around its health profile through the aggressive measures put in place by Michael Bloomberg during his time as mayor. “He really turned it into quite a healthy city. Twenty years ago it had some of the shortest life expectancy in the US. Under Bloomberg the Aids epidemic was under control, trans fats were banned from restaurants, and for every dish they were required to say how many calories. " The rate of obesity in children fell by 5.6 per cent between 2006 and 2011.

“It sounds like the nanny state,” he said, “but New Yorkers are now among the healthiest in the US. It shows what can be done. There’s really an urgent need for action now. But there’s no magic formula. There’s no vaccine. That’s the big difference between it and infectious diseases.”