Former U.S. president Bill Clinton and Bill Gates, the world's richest man, took the stage on Monday to support the fight against AIDS.

Most of the strategies that allow people infected with HIV in the developed world to live productive lives can work in poor countries as well, Clinton and Gates, whose appearance was dubbed "Double Bill," told the 20,000 global delegates in the 16th International AIDS Conference in Canadian city of Toronto.

While outlining their priorities to end the epidemic, both talked about successes and the challenges of bringing antiretroviral therapies to people in developing countries.

They admitted that the turning point in the pandemic may not arrive until scientists develop a vaccine or some other form of preventive tool. Both also predicted that the story would have a happy ending because of the people involved in events such as the week long conference.

"It's a breathtaking human tragedy," that most people in rich countries who are infected with HIV live, while those in poor countries die, Clinton told the conference. "It's unacceptable."

In Africa, where the stigma of diagnosis with HIV prevents people from seeking treatment, it takes well-respected people in the community, such as a boxing coach, to spread the word about how the treatments have helped them to live, Clinton said.

Gates agreed, saying that in India, people who were HIV-positive needed a safe place to talk with each other about behavioral changes, such as how to negotiate the use of condoms.

Clinton, whose charitable foundation is largely focused on the HIV/AIDS cause, said visiting endemic regions gave him optimism for an AIDS-free future.

On a recent trip to Liberia, a country nearly destroyed by civil war, the college students he met were as bright and ambitious as any he has encountered, he said.

"The source of optimism is the human material," he said. "There is no shortage of intelligence, effort, dreams and drive anywhere in the world."

Gates called HIV/AIDS the "worst medical disaster ever in history," but said the conference, populated by 24,000 scientists, doctors and activists, fills him with optimism.

"There is a lot of energy in here," he said, "Overall, this is a story that will have a happy ending."

Gates and his wife, Melinda, head a foundation that has recently donated 500 million U.S. dollars to fighting AIDS, tuberculosis and malaria.

Developing health infrastructure, nutritious crops, water and sanitation in developing countries would help make people healthy and build economic prosperity, Clinton said.

With resources and investment, people in the developing world would do well, Clinton added.

About 45 million people live with the virus and almost 3 million died last year as a result of the condition, the United Nations AIDS agency (UNAIDS) estimated.

Source: Xinhua