South Africa faces a new phase of the Aids epidemic in which mortality will escalate, a conference has heard.
Campaigner Zackie Achmat (l) has become a symbol for many
"South Africa is... entering a period that will be marked by rapidly rising death rates," researcher Quarraisha Abdool Karim told delegates in Durban.
The warning came at South Africa's first national conference on Aids and HIV.
Protests have continued against the government's refusal to implement an anti-retroviral drugs programme which could prolong the life of Aids patients.
Members of the country's biggest Aids campaign group - the Treatment Action Campaign (TAC) - marched on the conference centre.
They were led by Zackie Achmat - the country's most outspoken Aids activist - who has now decided to take anti-retroviral drugs.
In a protest publicly supported by Nelson Mandela last year, he had refused to take them until the government made them available generally.
"I decided to take my medicines," he said to a roar from the crowd on Monday.
Activists say the delay in implementing a national treatment policy is costing hundreds of lives a day in a country where nearly five million are HIV-positive.
"The incidence of HIV infections may be close to saturation in
South Africa but it would be foolish to see this as success," Ms Karim of Natal University said.
She predicted a rising number of deaths along with
a continuing high rate of infections.
"A rising mortality rate should not be allowed to mask the fact that many people are still being infected," Ms Karim warned.
"We have reached a critical period in this epidemic, which will have major implications for decision-makers."
South African Health Minister Manto Tshabalala-Msimang was jeered at the opening of the meeting on Sunday as she attempted to defend the government's controversial treatment policies.
"We have never said we don't need anti-retroviral drugs," Ms Tshabalala-Msimang told the BBC. "The issue has been the cost.
"I am saying now, thanks to our scientists as well, that we know that traditional and nutritional supplements work as well."
She also stood by a decision by South Africa's Medicines Control Council (MCC) to look more closely at a key anti-Aids drug, Nevirapine - a drug considered vital by the World Health Organisation.
The row over the safety of Nevirapine - the only approved anti-retroviral drug - is also dominating the conference attended by international experts.
Last week, the MCC threatened to ban Nevirapine, even though research has shown it can cut mother-to-baby infection rates by nearly a half.
TAC - which last year won a court victory forcing the state to provide Nevirapine - has voted to resume its campaign of civil disobedience in its pursuit of anti-retroviral drugs for all.
A spokesman for the group said Mr Achmat - who is 41 and was diagnosed with HIV in 1990 - would start taking the anti-retroviral drugs as soon as he had undergone the relevant medical tests.
"We need Zackie to live through this and not become a victim of the government's denialism and arrogance," Nathan Geffen said.