Aids entered the medical domain quietly in 1981 with a report in Los Angeles of five cases of severe pneumonia caused by a parasite, Pneuocystis carinii, common in animals but uncommon in man.

All five were young homosexuals who engaged in anal intercourse with multiple partners, had histories of sexually transmissible diseases and used mind-altering drugs. They became fatally ill with uncontrollable diarrhoea, weakness and wasting.

Also in 1981, a series of cases of an unusual form of skin cancer, Kaposi's sarcoma, was reported in New York City in young homosexual men, many of whom had the same kind of pneumonia. Similar cases attracted attention in Los Angeles, San Francisco and New York City. All were homosexual men in their twenties who used drugs freely. Their condition was described in the official publication of the US Centres for Disease Control as a gay-related wasting syndrome and then, after further investigation of immune status, as "Gay-related Immune Deficiency" (Grid).

A similar disease was noted in heterosexual drug addicts who shared needles for injection of heroin and a similar loss of immunity was described in haemophilic patients who began about this time to receive transfusions of the corrective Factor VIII, prepared from pooled donations of blood. Grid was then named the Acquired Immune Deficiency Syndrome.

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Thus defined, Aids spread rapidly in the United States among promiscuous homosexual men and drug addicts, and then in conurbations in Europe and Australia. There were no reports in females, older persons or children until similar cases were detected in much smaller numbers in women who used drugs or were partners of bisexual males.

In late 1983, Science magazine published a report from the Pasteur Institute in Paris claiming discovery of a new retrovirus in a culture from an enlarged lymph gland in an otherwise asymptomatic homosexual man. Workers at the US National Cancer Institute in Washington then claimed that the new retrovirus in this culture was one that they had already isolated from many homosexual men with Aids in the US. After some argument about priorities and patents, the virus presumed to be present in these cultures was named the Human Immune Deficiency Virus (HIV) and pronounced in 1984 by a US secretary of state to be the sole cause of Aids.

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In this way, Aids entered the public domain as a plague already affecting thousands in North America and as the start of a lethal global pandemic. This pronouncement, without confirmation by isolation of the original retrovirus, was accepted worldwide because antibodies, allegedly specific for the detection of HIV, were found in the blood of patients with Aids. Wider testing supported the belief that HIV had spread beyond the original risk groups to the general population. This became an accepted dogma.

Until this point, the origins of Aids had been investigated openly and without prejudice. With the "discovery" of HIV, universally infectious retrovirus, and the conversion of this hypothesis into a dogma, all dissent began to be suppressed.

At the time I was a consultant to the World Health Organisation on social and behavioural aspects of communicable diseases. I was impressed by the fact that, in all countries with reliable registration procedures, full-blown Aids was confined to the original risk groups of homosexual men and drug users and their partners.

This trend was so invariable by 1987 that predictions based on appropriate formulae were accurate in numbers and distribution, year by year. There was no evidence in 1987 that Aids was being spread heterosexually in general populations. The data I offered to the WHO received attention internally, but were barred from publication. Medical literature exploded, with worldwide media coverage, to accommodate the consensus view that Aids was becoming a global pandemic.

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In 1987, Professor Peter Duesberg, a pioneer in retrovirology at the University of California, Berkeley, suggested that HIV was a latent virus incapable of causing Aids, which was due either to suppression of immunity by toxic drugs or to a recrudescence of other diseases. A fuller statement of his views, published by the US National Academy of Science in 1989, caused a furore. Duesberg's arguments were not debated and he was almost universally demonised.

Also in 1989, the Royal Society organised a symposium on epidemiology. This endorsed predictions of tens of thousands of cases in the UK by 1992. When I suggested that this was exactly what was not happening, the society's Transactions invited me to submit my analysis. A four-year correspondence ensued, ending in 1994 when my paper was rejected. Among the file of correspondence were such comments as: "Why should I read a paper by someone who believes the earth is flat?" Time, however, has shown that my predictions made in 1989 were accurate within 10 per cent of registration of Aids cases, whereas those published in the symposium, official projections and other expert quarters were exaggerated, often by orders of magnitude.

Since 1990, Nature, Science, the New England Journal of Medicine and the British Medical Journal have rejected papers containing data that throw doubt on the claim that Aids is capable of causing epidemics in general populations of developed countries by heterosexual transmission of HIV. Some of the papers also challenge the hypothesis that HIV is the sole cause of Aids. The Lancet has published some letters, but has refused to publish fuller reasons for dissent.

Secretive censorship is familiar to anyone who has questioned orthodox views on Aids. The result is that essential questions are debated only in lesser journals. There are, naturally, vested interests involved: many individuals receive high rewards for their work within orthodox Aids science. Underlying much of this, the pharmaceuticals companies have their own agenda.

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This censorship is not unique but, in my 57 years as a professional, I have never encountered anything like it, nor did I think I ever would in the world where difference of opinion is the sine qua non of all advance.

Gordon Stewart is emeritus professor of public health at the University of Glasgow.

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