But they describe themselves as independent voices who face censorship and are treated as latter-day heretics for daring to question the prevailing HIV/Aids orthodoxy.
South African President Thabo Mbeki has become a champion for a small but vocal minority of medical and lay opinion which says HIV does not cause Aids.
From the perspective of most Aids organisations and specialists in the field, this minority - whose members are known as HIV/Aids dissidents or sceptics - persists in adhering to views that were discredited years ago.
But they describe themselves as independent voices who face censorship and are treated as latter-day heretics for daring to question the prevailing HIV/Aids orthodoxy.
It is this position that Mr Mbeki has embraced by accusing critics of South Africa's Aids policy of waging "a campaign of intellectual intimidation and terrorism".
Cause of Aids
The central tenet of Aids scepticism is that HIV is a harmless retrovirus which plays no role in Aids, although its presence may be a marker for people who have the disease.
This is in direct contradiction to the dominant view that HIV attacks the body's immune system, usually leading carriers to develope Aids, which inevitably results in death.
Following on from this fundamental difference is the clash over the administration of drugs to fight the virus and reduce mortality rates.
Sceptics say that the toxicity of Aids treatments, such as the anti-HIV drug AZT, actually promotes Aids among carriers of the virus.
This goes against the overwhelming body of evidence which shows that treatments developed in recent years have proved effective in slowing the onset of Aids and significantly reducing the rate of transmission of the virus from HIV-positive mothers to their babies.
Indeed the administration of drugs known to be effective against HIV, and their efficacy in holding off Aids, is perhaps the most conclusive proof of a connection between the two.
Lead heretic
The leading light of Aids scepticism is Peter Duesberg, Professor of Molecular and Cell biology at Berkeley, who begin to question the link between HIV and Aids in 1987.
Prof Duesberg offers conventional pathogenic factors as the cause of Aids: drug use, promiscuous homosexual activity, blood transfusions, parasitic infections and malnutrition.
Another, less radical, sceptic is Robert Root-Bernstein, Professor of Physiology at Michigan State University. He allows a role for HIV in the onset of Aids, but a less central one than put forward by the majority of researchers.
In the main, sceptics believe that tying Aids exclusively to HIV infection prejudices the search for other explanations and possible cures for the disease.
In some cases they also insist that it is in the interest of much of the medical profession and pharmaceutical industries to perpetuate the "myths" about HIV and Aids.
Strange alliance
Critics of the sceptics wonder how the South African leadership comes to align itself with what they see as discredited and counter-productive theories.
One reason could be that, although drug therapy has become more popular and more available in the developed world, at an annual cost of about $10,000 it is beyond the reach of most patients in African countries.
Durban will host the next world Aids conference in July, and Aids activists say Mr Mbeki's stance may be to pressurise the drugs industry in the run-up to the conference to reduce prices for Africa, which has the world's worst Aids figures.
But it is apparent from the published writings of Duesberg and others that they largely ignore Aids in Africa, drawing most of their conclusions from the behaviour of certain "at risk" groups in the US and Europe such as homosexuals and intravenous drug users.
If they were to consider Africa, they might conclude that HIV and Aids have spread so dramatically because of heterosexual sex in increasingly mobile and sexually promiscuous communities.