The new government is now trying to hasten the expansion of antiretroviral treatments. The task is urgent. South Africa today is home to 5.7 million people who are H.I.V.-positive  more than any other nation, almost one in five adults. More than 900 people a day die here as a result of AIDS, the United Nations estimates.

Since the party forced Mr. Mbeki from office and some of his loyalists split off to start a new party, rivalries have flared and stories about what happened inside the A.N.C. have begun to tumble out, offering unsettling glimpses of how South Africa’s AIDS policies went so wrong.

From the first year of his presidency in 1999, Mr. Mbeki became consumed with the thinking of a small group of dissident scientists who argued that H.I.V. was not the cause of AIDS, his biographers say.

As president he wielded enormous power, and those who disagreed with him said they feared they would be sidelined if they spoke out. Even Nelson Mandela, the revered former president, was not immune from opprobrium.

In a column in The Sunday Times of Johannesburg on Oct. 19, Ngoako Ramatlhodi, a senior party member now running the party’s 2009 election campaign, recounted how Mr. Mandela, known affectionately as Madiba, was humiliated during a 2002 A.N.C. meeting after he made a rare appearance to question the party’s stance on AIDS.

Mr. Ramatlhodi described speakers competing to show greater loyalty to Mr. Mbeki by verbally attacking Mr. Mandela as Mr. Mbeki looked on silently. “After his vicious mauling, Madiba looked twice his age, old and ashen,” Mr. Ramatlhodi wrote.

Mr. Ramatlhodi himself acknowledged in a recent interview that in 2001 he sent a 22-page letter, drafted by Mr. Mbeki’s office, to another of Mr. Mbeki’s most credible critics, Prof. Malegapuru Makgoba, an immunologist who was one of South Africa’s leading scientists. The letter accused Professor Makgoba of defending Western science and its racist ideas about Africans at the expense of Mr. Mbeki.