Sir, - Dr Geoffrey Roberts (July 19th) chides you on your coverage of the recent International AIDS conference and specifically on President Mbeki's divisive and troubling response to the crisis in Africa. In so doing, he perpetuates the myth that HIV is not the cause of AIDS, stating that "it is not scientifically established fact but just one hypothesis among many". He claims that alternative views are held by hundreds of other scientific commentators.
If that is true, then none of them knows anything about AIDS. This sort of muddled thinking, reinvigorated by President Mbeki, led the international scientific community to release the Durban Declaration, a statement signed by over 5,000 scientists and published on July 6th, which says unequivocally that HIV is the cause of AIDS.
Dr Roberts notes that he is not a scientist. However, he is a historian and he should know that the microbial origin of diseases has been accepted for over 100 years based on Koch's postulates. These are a series of scientific observations that, when established, determine that a micro-organism causes a certain disease - for example, that mycobacterium tuberculosis causes TB, or that the measles virus causes measles. These postulates are that there is epidemiological association (the suspected cause must be strongly associated with the disease); that the suspected pathogen can be isolated - and propagated - outside the host; and that transfer of the suspected pathogen to an uninfected host, man or animal, produces the disease in that host. HIV satisfies all of these criteria: the virus is found in all cases of AIDS; the virus can be recovered from patients with AIDS and grown in the laboratory; and transmission of the virus to others causes AIDS in the recipient. Many additional lines of evidence that prove that HIV causes AIDS are well summarised elsewhere.
President Mbeki's ill-advised decision to re-open a debate most of science had thought was over is unhelpful because it diverts attention from the true problems of AIDS in Africa and from the inadequate response of the South African government to the crisis. HIV, the cause of AIDS, is the enemy. Focusing on it, preventing its transmission and treating its victims should be the priority, not perpetuating myths that should go the way of the flat earth. -Yours, etc.,
William G. Powderly, MD, FRCPI, Professor of Medicine, Chief, Division of Infectious Diseases, Washington University School of Medicine, St Louis, Missouri, USA.