The decade of that AIDS was both widespread and untreatable in the developed world – roughly 1985 to 1995 - marked a historic low point in diagnoses of sexually transmitted diseases in countries like the USA and UK. See below, for instance, for gonorrhoea diagnoses, which peaked briefly after world war two and then for a prolonged period from 1970-85.

HIV incidence has also increased among risk groups. For instance, according to UNAIDS (UNAIDS, 2001), HIV incidence (new diagnoses) in gay men increased from 0.6% a year in the late 1990s in Vancouver to 3.7% a year in 2000; from 1.16% in 1996 in Madrid to 2.16% in 2000; and from 1.1% in 1997 in San Francisco to 1.7% in 2000. Increases were also reported in London

But was this due to decreased condom use? Among the UK population in general, the 1990 and 2000 National Surveys of Sexual Attitudes and Lifestyles (NATSAL)(Johnson, 2001) found that consistent condom use among the sexually active population as whole increased from 17 to 24 per cent during the 1990s, even as the rate of STIs also increased.

NATSAL found that the effect of increased condom use had been more than cancelled out by other demographic changes – to which the increased condom use was probably consequent.

• The mean number of lifetime partners had increased from 8.6 to 12.7 in men and from 3.7 to 6.5 in women.
• Concurrent relationships – which are an extremely important factor in the spread of STIs, and which are cited as an important contributing factor to the HIV rate in Africa – increased from 12 per cent to 14 per cent in men and from 5 per cent to 8 per cent in women.
• Age at first sex declined from 21 in women and 17 in men in the 1990 survey to 16 for both sexes for teenagers included in the 2000 survey.
• The proportion of British men who had a male partner increased from 3.6 per cent to 5.4 per cent.

This is a reminder that many other risk factors, some of them modifiable and others hardly so, or which it would be difficult to change, produce changes in the rates of STIs.

But condom use in gay men certainly declined during the late 1990s, with the rates of unprotected sex increasing almost as soon at combination therapy became available in 1996 (in the USA) and in 1997 (in Britain). A survey in San Francisco (Centers for Disease Control, 1999), for instance, found that the proportion of gay men who sometimes practised anal sex without condoms increased from 30.4 per cent in 1994 to 39.2 per cent in 1997.

These figures were almost exactly mirrored, with a year’s time lag, by the figures in the annual UK Gay Men’s Sex Surveys (1999-2003) and their predecessors. From about 33 per cent of gay men who had anal sex doing it unprotected in the early 1990s, this increased from 1997 onwards and reached a peak of 45 per cent in 2000.

Since then, however, there is some evidence that the amount of unprotected sex among gay men has reached a plateau, at least in the relatively unmarginalised gay populations of US urban centres. A more recent survey from San Francisco (Prabhu 2004) found some evidence of a levelling-off of unprotected sex after 2001. More importantly, the amount of unprotected sex which was or could potentially be between partners of different HIV status (serodiscordant) showed a more distinct decline since that date.

An annual survey of gay men using London gyms (Elford 2005a) found that the percentage of gay men reporting ‘high-risk behaviour’ with a casual partner increased from 6.7 to 15.2 per cent between 1998 and 2001 but remained stable after that, with the figure for 2004 being 14.7 per cent.

The evidence from the large annual UK Gay Men’s Sex Survey is harder to interpret as questions are not always asked in standardised ways. But this appears to indicate a continued increase in unprotected sex between gay men in general, rather than a levelling off, from 33 per cent in 1993 to 54.4 per cent in 2003. UAI in itself does not imply HIV transmission, but there is also incomplete evidence that rates of potentially and definitely serodiscordant sex are increasing.

However an unpublished study by Jonathan Elford (Elford 2005b) suggests that rates of serodiscordant sex between gay men in London are levelling off, and may be falling in HIV-positive men – see the next section for details.

One consistent finding from all these surveys has been that HIV-positive men have a great deal more unprotected sex than HIV-negative men. Data from the 2004 San Francisco Department of Public Health HIV Epidemiology Annual Report (2004) show that the increase in unprotected anal intercourse among gay men since 1998 is entirely among HIV-positive men.

We will revisit the subject of exactly why HIV positive gay men have more unprotected sex, who they are having it with, and what the implications are for HIV, in the next section.

Meanwhile, however, despite all the above reservations and complexities of behaviour, it is important to remember that condoms remain the most effective and most widely used HIV prevention method by sexually active people, and that in high-risk populations where condoms are widely available, half of all acts of sexual intercourse take place with a condom.

This leads us to the best way to use them.