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Serosorting or seroguessing?

Some sexually active adults serosort—they have sex with people of the same HIV serostatus. In theory, serosorting should reduce the transmission of HIV. However, some people who serosort do so to avoid the use of condoms during insertive sex.

Researchers in Australia have been studying the sexual behaviour of HIV-positive and HIV-negative men over the past several years. They have found that some men, rather than having explicit conversation about serostatus with casual sex partners, were making assumptions or guesses about whether or not their partners were HIV positive. Based on these guesses, the men would then proceed to have unprotected anal sex with men they assumed to be of the same HIV status. The Australian researchers termed the behaviour of making assumptions about a person’s HIV status “seroguessing.” This behaviour can place people at risk for HIV infection. Seroguessing has also been described by researchers in Canada and the United States.

The Australian researchers recruited men in two groups as follows:

Positive Health group – recruited 729 HIV-positive gay men
Health in Men (HIM) group – recruited 1,427 HIV-negative gay men

Men in both groups were mainly of Anglo-Australian descent and were interviewed by researchers about their sexual and social behaviour. Participants in the HIM study were regularly tested for HIV and their average age was 36 years. The average age of HIV-positive participants was 46 years.

Results—trends in time

Over time, both HIV-positive and HIV-negative men increasingly disclosed that they had unprotected anal sex with casual sex partners who had the same HIV status.

When asked how they knew about their casual partner’s HIV status, some men assumed or guessed their partner’s status, as follows:

HIV-positive men – 27% guessed the HIV status of casual sex partners
HIV-negative men – 34% guessed the HIV status of casual sex partners

According to the researchers, their study “exposes the fact that currently a high proportion of both HIV-positive and HIV-negative men are indeed seroguessing…[and then having unprotected anal sex].” In a strange finding, the study team found that whether the men in the study directly discussed HIV status or seroguessed “did not seem to affect the men’s decision to engage in unprotected anal intercourse.”

Sexual and risk context

HIV-negative men who engage in serosorting are already at risk for HIV infection because of the following factors:

There is a delay between HIV exposure and the immune system’s ability to produce antibodies in the blood. This delay is sometimes called the “window period” and is variable, lasting several weeks. During this time, because antibodies are not yet present, it is possible that HIV tests that rely on the detection of antibodies may not produce a positive test result, even though infection might have occurred.
Therefore, men who engage in unprotected anal intercourse or other high-risk activities after their last negative HIV test may become infected and, at least initially, test negative if the test was performed during the window period when antibodies were not produced.
Seroguessing adds to the uncertainty about HIV risk.

Taking all of these points into account, the researchers note that “some of the risk reduction afforded by HIV-negative serosorting may be reversed by a high degree of seroguessing.”

Non-disclosure and guesses

Based on the results of the current and past studies, the Australian researchers found that HIV-positive men are increasingly disclosing their status to potential casual sex partners. However, also based on the current and past research, the team found that “a substantial proportion of men do not disclose serostatus to casual sex partners or do it occasionally depending on the particular circumstances of each encounter.” The research team also stated: “While many HIV-positive men are not disclosing their status, many HIV-negative men are making frequent and therefore often incorrect assumptions about the serostatus of their partners.”

Enhancing prevention education

HIV infections are increasing in gay communities in high-income countries, very likely due to unprotected anal sex and seroguessing. The Australian researchers encourage organizations that develop HIV prevention programs to take into account “contemporary changes in attitudes and behaviours of gay men.” Such programs, they add, “should encourage active risk reduction as opposed to seroguessing and passive risk taking.” Moreover, the research team notes that policies and programs should “address stigma and discrimination due to HIV serostatus and build skills in HIV discussion among both HIV-positive and HIV-negative people.” Perhaps the most important recommendation of the Australian researchers is this: HIV education should “address the fact that HIV-negative men who engage in unprotected anal intercourse due to assumptions of seroconcordance may be at high risk of HIV infection.”

Related Canadian research

Ontario professor Barry Adam, working with a team from the AIDS Committee of Toronto, conducted detailed interviews with gay and bisexual men who engaged in unprotected anal intercourse most or all of the time. They found that different men—depending on HIV status and social and sexual networks—formed different assumptions about their casual sex partners and what behaviours they considered normal. The Ontario researchers also found that because of seroguessing and assumptions of which they may not be aware, HIV-negative men who engage in serosorting and unprotected anal sex may be at high risk for HIV infection.

—Sean R. Hosein

REFERENCES:

Scheer S, Kellogg T, Klausner JD, et al. HIV is hyperendemic among men who have sex with men in San Francisco: 10-year trends in HIV incidence, HIV prevalence, sexually transmitted infections and sexual risk behaviour. Sexually Transmitted Infections. 2008 Nov;84(6):493-8.
Likatavicius G, Klavs I, Devaux I, et al. An increase in newly diagnosed HIV cases reported among men who have sex with men in Europe, 2000-6: implications for a European public health strategy. Sexually Transmitted Infections. 2008 Nov;84(6):499-505.
Sullivan PS, Hamouda O, Delpech V, et al. Reemergence of the HIV epidemic among men who have sex with men in North America, Western Europe and Australia, 1996-2005. Annals of Epidemiology. 2009 Jun;19(6):423-31.
Zablotska IB, Imrie J, Prestage G, et al. Gay men’s current practice of HIV seroconcordant unprotected anal intercourse: serosorting or seroguessing? AIDS Care. 2009 Apr;21(4):501-10.
Adam BD, Husbands W, Murray J, et al. Silence, assent and HIV risk. Culture, Health & Sexuality. 2008 Nov;10(8):759-72.

Created on: 11/13/2009

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