Letter: The Sunday Times's rejection of the connection between HIV and Aids

Sir: The theory that Aids is caused by amyl nitrite inhalation was first proposed in the very earliest days of the epidemic; other explanations which were canvassed at that time included the idea that a multitude of sexually- transmitted infections could somehow 'overwhelm' the immune system, and the proposal that human sperm was itself an immunosuppressant. The HIV theory has come to be preferred because it provides a more credible framework than any of these others for integrating the totality of information about the disease.

It is the absence of this idea of competition among hypotheses that vitiates Mr Witherow's criticism. He does not say how the amyl nitrite hypothesis meets the difficulties he mentions better than the viral hypothesis does. He claims that predictions of the progress of the epidemic based on this hypothesis 'did not come true'. Were predictions based on the amyl nitrite hypothesis any more accurate?

What is far worse, however, is that he ignores the major features of the disease - above all, its transmission to recipients of blood and blood products - which have a simple explanation if Aids is caused by HIV infection but which are absolutely baffling if it is not.

Yours sincerely,

ANDREW F. W. COULSON

Musselburgh, Midlothian