?Nelson Mandela was a central figure in the AIDS movement. He was instrumental in laying the foundations of the modern AIDS response,? said Michel Sidibe, head of the Joint UN Programme on HIV/AIDS, or UNAIDS.
?His actions helped save millions of lives and transformed health in Africa. He broke the conspiracy of silence and gave hope that all people should live with dignity.?
Of Mandela's achievements, UNAIDS pointed to his decision in 2005 to go public with the news that his own son, Makgatho, had died of AIDS-related causes.
"His public revelation helped drive debate about HIV. And his support to people living with HIV helped to break down stigma and discrimination," UNAIDS said in a press release.
The Global Fund to Fight AIDS, Tuberculosis and Malaria paid tribute to Mandela's "special role" as a breaker of taboo.
"While other political leaders denied or ignored the spread of HIV, causing severe damage by hindering the implementation of effective treatment, Mandela spoke openly," it said.
The International AIDS Society (IAS), whose conferences have spearheaded the war on AIDS and the human immunodeficiency virus (HIV) that causes it, said the world "has lost an extraordinary statesman and human being".
"Mr. Mandela had the power to change hearts and minds, change policies and above all change the public's perception of the virus in the most affected region of sub-Sahara," said Bertrand Audoin, executive director of the IAS.
Failure to address the AIDS crisis in his country has been singled out as a weak spot in Mandela's record as the first president of post-apartheid South Africa, from 1994-1999.
But after he left office, stung by awareness of the problem, he threw himself into combatting discrimination and ramping up access to life-saving drugs through his 46664 Foundation, say activists.
Francoise Barre-Sinoussi, the Nobel-winning French scientist who co-discovered HIV, recalled Mandela's speech to the International AIDS Conference in 2000, which alerted the meeting to the tragedy unfolding in sub-Saharan Africa.
"He said, 'This is the one event where every word uttered, every gesture made, has to be measured against the effect it can and will have on the lives of millions'," she said.
?As a direct result of his speech, mother-to-child transmission in the region almost immediately became a priority and so did access to antiretrovirals.
"I have no doubt that his words that day did indeed save the lives of so many people and continues to do so."
South Africa's Treatment Action Campaign (TAC), which demanded that Mandela's successor, Thabo Mbeki, start distributing antiretrovirals to HIV-infected people, recalled when Mandela in 2002 donned a white T-shirt with the words "HIV Positive".
"In that moment he became one of us and made a powerful statement against stigma, at the same time sending a message to the then denialist government that people living with HIV are part of this country and should be given lifesaving treatment," TAC said.