The much feared break-out of the disease from the highest risk groups into the general population has not happened - yet - with anything like the rapidity that so concerned policy makers in the mid-1980s. The Government's "Don't die of ignorance" campaign, much criticised at the time, does seem to have influenced sexual behaviour and to have helped slow the spread of infection with HIV, the virus responsible for the disease.
Other countries quailed at the idea of lecturing their people on safe sex and, as a result, Spain last year had four times as many new Aids cases as Britain; France had three times and Italy twice as many.
Even before the Government campaign, Britain's gay community - one of the most afflicted - had started adopting safer sex practices. Roughly a decade later, in 1994, what had appeared to be a relentlessly rising graph of Aids cases among homosexuals started to decline. Between 1995 and 1999, according to official figures from the Public Health Laboratory Service, "it is expected that new Aids cases in homo/bisexual men may fall by 7 per cent".
A decade is the approximate "latency" period from infection to the development of full blown Aids and so the change in the incidence was an oblique, epidemiological demonstration of the linkage between HIV infection and unsafe sex.
However, the incidence of Aids is continuing to rise in the heterosexual community and among intravenous drug users, according to the PHLS figures. Any complacency could increase the spread of the disease, as the experience of Africa and south-east Asia demonstrates.
Globally, about 10,000 people become newly infected every day. More than 11 million Africans and about 4 million inhabitants of south-east Asia are infected with HIV. In the Third World the disease is largely spread by unprotected heterosexual intercourse.
But a significant number of people in Britain are dying from the disease. Some are gay men; some are intravenous drug users; some are haemophiliacs; and others have acquired the disease from heterosexual intercourse.
Viral diseases are not amenable to treatment with antibiotics, such as penicillin, which attack and kill only bacteria. Early hopes that existing anti-viral drugs might prove efficacious against HIV have been dashed.
Vaccination to boost the body's inbuilt defences against microbial attack is the most efficient method of combating viral infections. But HIV is a "new" virus of a type that was previously little understood. It carries its genetic material in the form of RNA rather than the more usual DNA and it insinuates itself into the body's cells, tricking them into converting the viral genetic instructions out of RNA into DNA and then inserting them into the cell's own double helix strand of DNA. The cell's biochemical machinery is hijacked into becoming a factory for the production of more and more copies of HIV.
But HIV has a further twist: the cells that it infiltrates are those of the immune system - the very ones that ought to be fighting off infections.
The early hopes of a quick fix were fuelled in the US by pressure from lobby groups on behalf of the dying. In recent times however, the focus of research has switched to lower profile work which recognises that humanity's struggle against this killer will be a long haul.Reuse content