By Jane Dreaper
BBC News health correspondent, Toronto
Former US President Bill Clinton has said Aids is a problem affecting many people indirectly because of migration and interdependence among countries.
Bill Clinton said no nation could ignore the HIV/Aids problem
"There's still a lot of problems out there and we still need much more prevention work," Mr Clinton told BBC News at the Toronto Aids conference.
He spoke of how he recently visited Africa to see work funded by his charitable foundation.
"There's a new sense we can turn it around," he said.
This is a personal issue for the former president. He told me that when he left office, he was troubled by the fact that he and other world leaders had not done enough to tackle the disease.
Why Aids matters
I put it to Mr Clinton that some people in the UK might look from afar at this huge conference in Toronto and wonder why they as individuals should care about the Aids/HIV epidemic.
"It will affect them at least indirectly - the UK, like America, has lots of immigrants from all over the world," he responded.
"Many come from countries that have significant Aids problems.
"But, more to the point, in an inter-dependent world, if the wealthy countries turn their backs, the world will be a much bleaker place."
Mr Clinton hopes that one day the US will host this international Aids conference, which takes place every two years.
The organisers say they would not hold it there at the moment because American cross-border controls make it difficult for people who are HIV-positive to enter the country and of course they play a key role in a gathering like this.
It is an issue that enrages HIV-positive people I have met.
Did Mr Clinton think that restriction should be reviewed?
"I do, I do," he said, adding that he had signed a bill continuing the policy because "it had so much else in it that was good and I didn't want to lose what was good".
"We have rising infection rates now among certain parts of our population - especially women of colour, who are vulnerable to enforced sex or are more likely to have partners who don't know their status," he said.
"Until we find a vaccine or cure, no nation can afford to look away from this."
Not surprisingly, Mr Clinton's international vision includes a reflection on the current terror threat.
"The central question for our time is not how you worship God, or even whether you worship God," he told me.
"It's whether you believe in this life you can be in possession of the absolute truth and you have the right to impose it on others - and therefore whether your differences are more important than our common humanity. That's the values crisis."
Mr Clinton also described climate change as a profoundly important issue, with the potential to radically alter and restrict the future of all people.
"I'm going to try to put that issue with my Aids and development work and hope to make a real difference," he said.
"I think climate change is an opportunity not just in rich countries but in poor ones as well.
"I talked to the prime minister of Ethiopia [Meles Zenawi] on my recent trip to Africa about their prospects for producing bio-fuels and developing Africa into an oil-free continent when it comes to transportation.
"That would actually be great for farmers' income, and for global warming, and for political stability in the world."
This former leader of the United States turns 60 at the weekend but clearly he does not have any plans to slow down and he still intends to make a difference.