“There are some who may argue that Jacob Zuma’s sex life is a matter of private morality or ‘culture’ but this is not so,” she said in a statement. “His personal behavior has profound public consequences  and he acknowledged as much when he apologized to the nation for having unprotected sex” with a woman who later accused him of rape.

Image Jacob Zuma was criticized after reports that he had fathered a child out of wedlock. Credit... Pierre Verdy/Agence France-Presse — Getty Images

Mr. Zuma was found not guilty in the 2005 rape trial, saying that the sex had been consensual. His accuser was a 31-year-old family friend. Mr. Zuma said she dressed seductively and crawled under the covers of his bed. He testified that he had sex with her in fear she would otherwise accuse him of rape.

At the time, Mr. Zuma was South Africa’s deputy president. He already had a huge and impassioned following. However, the trial also opened him to ridicule. The woman involved was H.I.V. positive, and Mr. Zuma testified that to minimize his risk from infection he took a shower.

With the president’s sex life now again in the news, his adversaries had an opportunity to mock him. The Rev. Theunis Botha, the acting leader of the Christian Democratic Party, said Mr. Zuma was “Tiger Woods, Bill Clinton and Henry VIII all in one.” He called for him to resign.

In a front-page commentary with the huge headline “Shame of the Nation,” the Sowetan newspaper said that in other democracies Mr. Zuma would be compelled to give up the presidency, adding that none of what he said on World AIDS Day “came from the heart.”

However heartfelt, the speech was more than talk. It was accompanied by a tangible step up in providing AIDS treatment and preventing the infection in newborns. The new policies were welcomed by the health community.

Mr. Zuma, a husky man with a shaved head, a 100-watt smile and more than a touch of charisma, is a combination of modernity and tradition, a statesman in well-tailored suits one day and a dancer in leopard skins the next.