Sir

The attempt by Stewart et al. (Nature 407, 286; 2000) to minimize the significance of the recent Durban Declaration (Nature 406, 15; 2000) affirming that HIV is the cause of AIDS raises several troubling issues.

Stewart et al. suggest the bulk of the declaration's 5,000 academic signatories may have inadequate credentials. Yet the signatories of the Stewart et al. Correspondence, who make up most of the 'HIV-denialist' membership of President Mbeki's AIDS advisory panel, are mainly known for their disagreement on AIDS with just about everyone else in academic science, medicine and public health. In contrast, the signatories to the Durban Declaration include the vast majority of scientists worldwide who publish on all aspects of HIV and AIDS.

Second, Stewart et al. distort the declaration's statement that there is “no end in sight” to the epidemic by taking the phrase utterly out of context. Enormous progress has, of course, been made against AIDS, all of it stemming from the fundamental knowledge that AIDS is directly caused by HIV infection. This knowledge has enabled a long string of consistent and fruitful observations about the pathogenesis of HIV and brought about a powerful new family of pharmaceuticals that, however imperfect, have dramatically reversed the death rate from AIDS wherever they have been used.

There is “no end in sight” only where poverty, greed, politics or misguided information blocks access to these advances. Sadly, people in developing nations are paying the price with their lives, nowhere more so than in South Africa. Women are being deprived of safe, proven methods of blocking neonatal transmission, efforts to improve access to the new drugs are being undermined and years of prevention work are being confounded.

Third, Stewart et al. cite four papers from the early 1980s as a basis for objecting to the Durban Declaration. Whatever such papers say, they reflect only the knowledge available when they were written. Subsequent data have greatly refined our understanding. Why do Stewart et al. ignore 15 years of scientific progress?

Fourth, Stewart et al.'s claim that AIDS did not spread initially in Africa is simply incorrect. While the spread of HIV-1 and AIDS to sub-Saharan Africa was a later phenomenon, AIDS appeared in significant numbers more or less concurrently in several other African nations, Europe and North America in the early 1980s. Heterosexual transmission was evident almost from the beginning in Africa, as well as among transfusion recipients and haemophiliacs. Fear of an outbreak among Western heterosexuals was a valid concern. We were extremely fortunate in the United States to have a slow initial spread to heterosexuals, probably because the epidemic first broke out exponentially here among homosexual men, who do not routinely have sex with women. This observed pattern of HIV-1 spread is exactly what would be expected of a sexually transmitted disease with a first foothold in the gay male community. Today, heterosexual transmission is routine almost anywhere HIV-1 appears.

Although there may be some disparities in the ways AIDS affects people in developing nations compared with the West, there are no great mysteries. Higher rates of breast-feeding, for example, together with malnutrition and poor prenatal and delivery care, undoubtedly contribute to a higher rate of infant infection. The fact that many people in Africa have been unable to use prophylactic antivirals has also contributed enormously to the disparity in the rate of perinatal transmission compared with the West.

Finally, Stewart et al. argue that the HIV-denialists have had their views suppressed. On the contrary, scientists worldwide have shown excessive patience for the past 15 years. The accepted standard of science is to permit everyone to express their views, but also to hold people intellectually responsible for what they say. When a position is found faulty by the consensus of scientific opinion, principled dissenters go back to the lab and run new experiments in hopes of proving their point on a new day, rather than attacking the character of their critics and arguing their case to scientifically unqualified media and the lay public. The HIV-denialists are preaching to the very people at greatest risk now, the HIV-positive patient population itself.

Thousands of babies are born with HIV infection in South Africa alone, with little or no hope of a normal life. How high will the death toll have to be before the denialists see the error of their ways?