South Africa's third national AIDS conference opened in Durban on Tuesday with expressions of cautious optimism that the national response to the epidemic had a better chance of succeeding than ever before.

"At last a sense of hope permeates the air," said Graca Machel, international AIDS and women's rights activist and one of the conference's opening speakers.

The theme of the meeting, "Building Consensus on Prevention, Treatment and Care" is significant when considering relations between the government, researchers and NGOs working in the HIV/AIDS sector have been marked by tension and conflict. But in the past few months, Deputy President Phumzile Mlambo-Ngcuka and Deputy Health Minister Nozizwe Madlala-Routledge have led efforts to re-energise the fight against HIV/AIDS by building partnerships with civil society.

While other speakers echoed Machel's message of hope, they warned that South Africa has a long way to go if it was to reverse the epidemic.

Conference chair and CEO of the Human Science Research Council, Dr Olive Shisana, gave the conference's more than 4,000 delegates a sobering appraisal of the current state of the epidemic in South Africa.

In the 15 to 49 year age group, she said, 71 percent of all deaths in South Africa are due to AIDS, while more than 500,000 new infections occurred in 2005 alone.

HIV prevention messages had failed, Shisana told delegates, because they had not taken into account South Africa's cultural context in which, for example, multiple sexual partners and extramarital affairs are accepted as the norm.

"We have the means to stem the tide," she added, listing South Africa's state-of-the-art technical means, world-class scientists, considerable financial resources and active civil society sector.

UNAIDS head, Dr Peter Piot praised South Africa's "remarkable progress" in scaling up antiretroviral treatment over the past two years since the last national AIDS conference and its ambitious new National Strategic Plan.

If South Africa can achieve the aims of that plan, he said "the country could be well on the way to leading Africa into a new phase in the AIDS response."

But adopting the plan is just the beginning. "The real work starts now," he added.

Formally opening the conference, Mlambo-Ngcuka agreed that the biggest challenge ahead, and the focus of the next three days of the conference, would be implementation.

The new mood of optimism was only slightly marred by the announcement by Mlambo-Ngcuka, that the country's much maligned health minister, Dr Manto Tshabalala-Msimang had withdrawn from the programme. The conference was to have been the minister's first major public appearance after a long period of absence due to illness. Mlambo-Ngcuka admonished the conference's organisers for her withdrawal, suggesting that it was the result of her not being given an appropriately prominent place in the conference programme.