ONE OF the more extraordinary claims of the Aids 'mythologists' is that the spread of HIV in other parts of the world has no relevance to Britain. With this they can sweep away the scientific fact that there are more cases of heterosexual Aids in the world than homosexual Aids.
What they seem to ignore is that Aids in the United Kingdom is the result of the virus being imported into the country by infected blood products, business travellers and tourists.
Aids is a global pandemic where national and cultural boundaries are not respected. Already, scientists are detecting a rise in HIV prevalence among British businessmen who have been the customers of prostitutes in Thailand, where the spread of HIV in the past five years has been explosive.
Scientists working in Thailand say that the country has an excellent system for monitoring the spread of HIV - unlike some African countries where surveillance is notoriously unreliable. They maintain that the dramatic rise in heterosexually acquired HIV in prostitutes and their customers is genuine and that only sensible health education could help to avert a similar situation arising in Britain.
Thailand has experienced two HIV epidemics, one among drug users who have shared contaminated needles and syringes, and the other among prostitutes. Both have taken only a few years to become established.
Researchers there have now seen the first signs of another wave of the second epidemic as the virus begins to seep out from 'fast-track' heterosexuals - such as prostitutes and their clients - into the wider population. Rural areas are showing signs of an increase in HIV.
Heterosexual Aids and HIV infection have also increased dramatically in parts of India in recent years, following a pattern that has become established in many cities and countries of sub-Saharan Africa. In Nairobi, for instance, between 60 and 80 per cent of prostitutes are infected with HIV.
Scientists believe there are two peaks to the Aids epidemic in Africa. The first has already happened - in prostitutes and their clients. This sowed the seeds of a second peak as male clients pass the virus to wives and girlfriends, who may then pass it on to others, including their children.
Epidemiologists in the UK, such as Anne Johnson from University College London, have consistently emphasised that the British heterosexual population is not isolated from the rest of the world. Because current cases of heterosexual Aids are mostly attributed to contacts of drug users or foreigners, that does not mean they will always be.
'We are observing a series of interacting epidemics,' she said, 'and after only 10 years it is not surprising that we can still trace chains of transmission to the early epicentres.'