Bill Gates, whose foundation is spending $2-billion on Aids research and treatment, called for faster development of gels and pills to give women more control in preventing the disease.

The best chance of stopping the epidemic is to develop products that women can use to prevent infection with HIV, the deadly virus that causes Aids, Gates said at the opening of the 16th International Aids Conference in Toronto today. Treating everyone with the disease will be impossible unless health officials succeed in slowing the infection rate, he said.

The Bill and Melinda Gates Foundation, the world's largest philanthropic organization, plans to increase its spending for research on vaginal gels called microbicides that are designed to kill HIV on contact and on the use of Aids drugs for preventing the disease, Gates said. About 40-million people have ,the virus, and women now account for almost 60% of infections in Africa, according to the United Nations.

“Today, women have to rely on men to agree to abstinence or to using condoms, and it's not working,'' said Gates, who spent most of July traveling with his wife, Melinda, through Africa, which he called the center of the Aids epidemic. “A woman should never need her partner's permission to save her own life.''

The rate of new infections among girls aged 15 to 19 is five times higher than that of boys in the same age group, according to the United Nations. Scientists are seeking new preventive measures that won't take as long to develop as vaccines, which may be as much as a decade away.

Increases in funding from organizations such as the Global Fund to Fight Aids, Tuberculosis and Malaria and the President's Emergency Plan for Aids Relief have increased the number of HIV patients receiving treatment in low and middle-income countries by about 450 000 a year between 2003 and 2005, Gates said. Over the same period, the number of people who became infected with the disease averaged 4,6-million a year.

“In other words, for each new person who got treatment for HIV, about ten people became infected,'' he said. “Even during our greatest advance, we are falling behind.''

Assuming the lowest cost for the standard cocktail of medicines, now about $130 a year, and costs of at least $200 a year for personnel, lab work and other expenses, treating everyone infected with HIV would cost about $13-billion every year, Gates said.

“To put that number in context, remember that PEPFAR, a historic expansion in funding, designates about $1,5-billion a year for treatment.''

The figures don't count the cost of the “much more expensive'' second-line therapies and also assume no increase in the total number of people who will need treatment.

“Treatment without prevention is simply unsustainable,'' he said.

Cultural stigmas and the inequality of women in many countries fighting the Aids epidemic means that new prevention methods need to be products that women can use themselves, Melinda Gates said today at a media briefing during the conference.

“You have to put the power in the hands of women,'' she said.

Researchers are testing 16 microbicides in women, five of them in the last stages of clinical trials. The Gates Foundation has donated $124-million for microbicide research.

“Governments should make the search for new prevention tools, such as microbicides, a bigger priority in their budgets,'' Melinda Gates said.

The Gateses spoke at a media briefing and at the opening ceremony for the conference at Rogers Centre, the stadium where the Toronto Blue Jays baseball team plays. The conference is expected to draw more than 24 000 researchers and advocates to discuss Aids prevention, care and treatment.

Canadian Prime Minister Stephen Harper, who took office in February, was the target of criticism during the ceremony for not attending the conference, which is held every two years and this time includes former US President Bill Clinton.

“Mr. Harper, the role of prime minister includes the responsibility to show leadership on the world stage,'' said Mark Wainberg, who is the conference co-chair and director of the McGill University Aids Centre in Montreal.

“Your absence sends a message that you do not regard HIV/Aids as a critical priority, and clearly all of us here tonight disagree with you.''

Harper, who leads a Conservative Party government, didn't attend because of scheduling conflicts, said his spokesman Stephane Rondeau, who added that former Prime Minister Jean Chretien skipped the 1996 conference in Vancouver.

Canada's Minister of Health Tony Clement spoke instead of Harper and drew a mixture of boos and applause from participants when he took the stage.

More also needs to be done to test the preventive power of drugs that are given to people once they become infected with the virus, Melinda Gates said.

A study that will be presented at the meeting found that one such medicine, Gilead Sciences Inc.'s Viread, was safe for use as a method of prevention. Because of logistical obstacles, researchers were unable to show whether the medicine is effective in blocking infection.

The US government and the Gates Foundation are funding other studies looking at Viread and a second Gilead medicine called Truvada to prevent infection.

The Gates Foundation's latest donation for Aids research was announced earlier this week, when the Seattle-based organization said it will give $500-million to the Global Fund Fight Aids, Tuberculosis and Malaria in a bid to increase the number of people in poor countries helped by life-saving drugs.

The Gates Foundation had a $29,2-billion endowment before Warren Buffett, the chairman and chief executive of Berkshire Hathaway Inc., said he would add an estimated $31-billion.