B, which stands in the original ‘ABC’ model for ‘Be faithful’, but also involves partner reduction as well as strict monogamy, has been called “The neglected middle child of ‘ABC’ (Shelton 2004). It is difficult to gather evidence on whether HIV prevention programmes have influenced target populations in the direction of monogamy and reduction of the number of sexual partners, and there has been remarkably little research into, or co-ordinated campaigns promoting, partner reduction as an end in itself.

This is to be regretted, because the rate of spread of HIV in a population is more sensitively dependent on the rate of partner change, whether relationships are concurrent and consecutive, and whether partners are drawn from the local village or the global community, than on any other variable. The spread of HIV is crucially dependent on the establishment of sexual ‘networks’: remove a few links from those networks and the chain of infection can no longer be maintained. One paper (Garnett 1998) put it this way:

“Heterogeneity in sexual behaviour is vital to generate a high sexual activity ‘core group’ within which HIV spreads rapidly. How far out of this core group the virus will spread depends on the patterns of mixing within populations.”

Another important aspect of reducing the rate of partner change is that it reduces the number of times people are likely to come across partners in early HIV infection. One paper (Pilcher 2004) calculated that, because people in acute HIV infection have much higher viral loads, up to a quarter of all HIV infections are spread by people within two months of themselves being infected, and the proportion could be even higher if concurrent STIs are taken into consideration.

One problem with research into monogamy and reduction in the number of sexual partners is that it takes two people to be monogamous. An example of the traps the faithful partner of an unfaithful one can fall into is illustrated by an April 2005 study (Thorburn 2005) which found that among Afro-American heterosexual men and women, lower levels of condom use and contraception were found among people who agreed with the statement 'known partners are safe partners' than among ones who agreed that ‘trusted partners are safe partners'.

One of the few places where a reduction in the number of partners can be teased out as a contributor to lower HIV incidence and prevalence is, once again, in Uganda. That HIV prevalence has fallen no one disputes (except in the war-torn north of the country). But the evidence as to the contribution of partner reduction and increased monogamy to the decline in the figures is still indirect.

According to the USAID report cited above: “In the mid 1990s, two large randomized trials at Rakai and Masaka in Uganda attempted to look at the impact of STI treatment on reducing HIV prevalence. Although both interventions reduced the rates of some STIs, there was no significant reduction in HIV incidence.

“According to an expert panel at the 2002 World AIDS Conference in Barcelona, the main reason for the lack of effect on HIV from STI treatment was the large decrease in risky sex/multiple partner trends that had occurred in Uganda by the time the STI trials began. Most HIV transmission therefore now occurs within monogamous regular partnerships, where one partner has undiagnosed HIV, but where bacterial STIs tend to be rare.”

Certainly a considerable reduction in the amount of ‘casual sex’ among the population had occurred by 1995, with 50-70 per cent declines in the number of people reporting it (see chart below):

INSERT CHART?

and Uganda was the only country in the area to report such declines around that time.

This decline appears to be evidence that it was not merely the ending of war and the restoring of civil order on Museveni’s accession in 1986, which would involve men returning from the army and militias to their families, which created this change in behaviour patterns.

According to Stoneburner and colleagues (2000), “Ugandans are relatively more likely to receive AIDS information through friendship and other personal networks than through mass media or other sources, and are significantly more likely to know of a friend or relative with AIDS. Social communication elements, as suggested by these kinds of indicators, may be necessary to bridge the motivational gap between AIDS prevention activities and behaviour change sufficient to affect HIV incidence.”

In other words, Stoneburner is arguing that the social diffusion model (see HIV Prevention: Which Methods Work?) in which there is (a) a wide personal acquaintance with HIV/AIDS in the population and (b) the encouragement and willingness to speak about it and pass knowledge on in informal social networks is the method that has worked to influence behaviour change, almost uniquely so far for an African country, in Uganda. The first is the inevitable consequence of a developing untreated epidemic: the second, however, can be influenced by political leadership and widespread awareness-raising work. Such work was, supporters say, initiated by Museveni when he started his AIDS awareness campaign in 1986, which included his famous ‘Zero Grazing’ policy, which urged monogamy on all Ugandans.

However there is recent evidence that this shift in behaviour in Uganda may have essentially happened in the decade from 1985 to 1995, but that in the last ten years a more ‘westernised’ pattern of behaviour involving the resurgence of extra-marital sex, but an increased use of condoms, may be becoming more common.

In the Wawer study cited above (Wawer 2005), which looked at behaviour change in the Rakai district from 1993 to 2004, the main driver of reduced HIV prevalence was found to be attrition of the HIV-positive population due to AIDS deaths, with a smaller contribution from increased condom use. During the study period, HIV prevalence had decreased from 17.5 to 11 per cent, but the annual incidence of HIV had not declined, and may have even slightly increase, from 1.3 to 1.7 per cent a year.

During the decade the age of sexual debut got younger again; 50 per cent of 19 year- old men had had sex in 2004 compared with 40 per cent in 1994. The proportion of men reporting two or more sexual partners had gone up from 20 to 27 per cent, and among who tested HIV-positive in the study from 40 to 68 per cent. However condom used had doubled during the same time, from 19 to 38 per cent, a high figure for Africa.

Is there evidence of partner reduction in other countries? In Zambia, there was a dramatic fall in HIV prevalence in young pregnant women (15-19) between 1993 and 1998, where the proportion living with the virus halved, from 28.4 per cent to 14.8 per cent. A study (Fylkesnes 2001)found “a dominant declining trend in HIV prevalence that corresponds to declines in incidence since the early 1990s attributable to behavioural changes,” which predominantly means a decline in casual sex.

In Ethiopia (Mekonnen 2003), a country with a more recent HIV crisis, the proportion of men who reported casual sex at two centres fell in just two years (1997 to 1999) from 17.5 to 3.5 per cent, and the proportion reporting visiting sex workers from 11.2 to just 0.75 per cent.

In Cambodia (UNAIDS 2002), HIV prevalence halved between 1997 and 2002, as did the proportion of men who reported visiting a sex worker over the year, while condom use, already high, increased less dramatically.

There is one paradox that one needs to be aware of in encouraging monogamous behaviour. In certain HIV-prevalence situations it can make no difference to HIV incidence at all. For instance, in Zimbabwe and South Africa steep declines in the incidence of bacterial STIs like syphilis and gonorrhoea have not been accompanied by declines in HIV. This fact was noticed by an unorthodox researcher, David Gisselquist, who used it as evidence for his theory that the majority of HIV in Africa is being spread by unsterilised medical needles (Gisselquist 2003).

But the real reason is probably to do with the fact that in these countries prevalence is so high that transmission within marriage or a monogamous relationship is now just as likely as it is during a casual encounter. A monogamous marriage only reduces HIV transmission risk if both partners going into it have the same HIV status, and in countries where HIV testing is the exception rather than the rule, encouraging monogamy may in certain circumstances have the effect of spreading HIV from a core group of sexually active men and their female partners into the female population at large.

What about vulnerable populations in the developed world? There is evidence from the early days of the epidemic (Low-Beer 2003) that gay men rapidly adjusted their sexual behaviour as soon as the first reports of AIDS appeared. Rates of sexually transmitted diseases and HIV incidence started falling almost immediately, particularly among the more socially cohesive white gay community, though we do not know what proportion of these declines were due to condom adoption, having fewer partners, or abstinence from sex.

The comment of the authors of the paper from which the chart below comes comment that “These responses preceded and exceeded HIV prevention.” However another way of looking at it, using a broader definition of prevention, is that they were the first examples of community-led HIV prevention. A chain of ‘grapevine knowledge’ spread by word of mouth through a closely-knit community is exactly the kind of response to AIDS President Museveni was trying to set up in Uganda.

In the post-HAART era, is a similar behaviour change in gay men possible? There is one intriguing piece of evidence that it might be. US researcher Thomas Dee (2005) used a mathematical model to relate changes in the rates of syphilis, gonorrhoea, TB and malaria in European countries to whether a country had legalised gay marriage or civil partnership.

Dee found a 24 per cent reduction in syphilis incidence and a non-significant reduction in gonorrhoea compared with countries with no gay marriage legislation, and found that the reduction in syphilis started at the same time the marriage legislation was introduced. The rates of the non-sexually-transmitted diseases did not change at the same time: neither did HIV diagnoses, but being a non-acute condition, these are subject to a ‘time lag’.

This is obviously a highly indirect piece of evidence and cannot say directly whether gay marriage leads to fewer extra-marital partners. It also compares gay marriage with STI rates in the entire population, though in the case of syphilis, it was gay men during this era who were most affected. However Dee’s analysis is conservative: he eliminated from his analysis every other possible variable such as improvements in other health and economic indicators which might also cause falls in STIs, and the difference in syphilis rates on the raw data alone is striking: the ‘gay marriage’ countries seem so far largely to have avoided the large increases in syphilis seen in countries like the UK.

If it really is true that, as Dee says “gay marriage will encourage [gay men] to form emotional and legal commitments…that will promote sexual fidelity and possibly reduce STI prevalence,” then it again demonstrates that the activities which most successfully reduce HIV incidence and/or risk behaviour may be very far from ones that look like most people’s idea of HIV prevention.

References

Dee, Thomas. Forsaking All Others? The Effects of “Gay Marriage” on Risky Sex. National Bureau Of Economic Research working paper no. 11327. See http://www.nber.org/papers/w11327 2005.

Fylkesnes K et al. Declining HIV prevalence and risk behaviours in Zambia: evidence from surveillance and population-based surveys. AIDS 15(7): 907-916, 2001.

Garnett GP. The basic reproduction rate of infection and the course of HIV epidemics. AIDS Patient Care STDs 12: 435-449, 1998.

Gisselquist D et al. Let it be sexual: how health care transmission of AIDS in Africa was ignored. Int J STD AIDS 14(3): 148-161, 2003.

Low-Beer D, Stoneburner R. Behaviour and communication change in reducing HIV: is Uganda unique? African Journal of AIDS Research 2(1): 9–21, 2003.

Mekonnen Y et al. Evidence of changes in sexual behaviours among male factory workers in Ethiopia.AIDS24: 17(2): 223-231, 2003.

Pilcher CD et al. Brief but efficient: acute HIV infection and the sexual transmission of HIV. J Infect Dis. 189(10): 1785-1792, 2004.

Shelton James D et al. Partner reduction is crucial for balanced "ABC" approach to HIV prevention. British Medical Journal 328: 891-893, 2004.

Stoneburner R et al. “Enhancing HIV prevention in Africa: Investigating the role of social cohesion on knowledge diffusion and behavior change in Uganda.”  Paper presented at 13^th International AIDS Conference, Durban, 2000. No abstract cited.

Thorburn S et al. HIV prevention heuristics and condom use among African-Americans at risk for HIV. AIDS Care 17(3): 335-344, 2005.

UNAIDS. Report on the global HIV/AIDS epidemic 2002. Geneva: WHO, 2002.

Wawer MJ et al. Declines in HIV Prevalence in Uganda: not as simple as ABC. 12^th Conference on Retroviruses and Opportunistic Infections, Boston, abstract LB27, 2005.