Research Paper Presents Serosorting As More Dangerous

As Gabriel Rotello and Andrew Sullivan debate whether "AIDS is over" in an ongoing online hissy fit of battling blog posts, Mad Professah came across the results of a study which bolsters Rotello's argument that "sero-sorting" (the practice of sorting your sexual partners by HIV status and then having unprotected sex with people of the same status) is actually more dangerous than not. An article in the May 31, 2007 edition AIDS by D.M. Butler entitled "Serosorting can potentially increase HIV transmissions" used a mathematical model to numerically estimate the risks of HIV transmission due to serosorting between men of differing HIV statuses having unprotected sex.

The model for ‘HIV-negative’ individuals took into account the transmission risks involved at different stages of HIV infection. Unsurprisingly, the investigators calculated that the transmission risk per 10,000 for individuals who were actually HIV-negative was zero. For individuals who believed themselves to be HIV-negative, but who had chronic, asymptomatic HIV infection, the transmission risk was calculated as seven in 10,000. This risk increased for individuals thinking themselves HIV-negative, but with advanced HIV infection to 36 in 10,000. The highest transmission risk of all was for ‘HIV-negative’ individuals with acute HIV infection who had a transmission risk of 82 in 10,000.

The investigators then modelled the risk of HIV transmission from individuals who knew they were HIV-positive and disclosed this status. They calculated that asymptomatic individuals not taking antiretroviral treatment had a transmission risk of 7 per 10,000. This risk fell to 1 per 10,000 for individuals taking stable and effective antiretroviral therapy. However, for individuals with advanced HIV disease with risk was 36 per 10,000.

“During the period of recent HIV infection, individuals typically have a much higher viral burden than they do for most of the time they are infected”, write the investigators. They add, “as the proportion of recently infected potential sex partners in the population increases, the effectiveness of disclosure for preventing HIV transmission by serosorting decreases.”

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Our conservative calculations show that serosorting based on disclosure is not likely to be an effective prevention strategy when the prevalence of recently infected ‘HIV-negative’ disclosers comprises approximately 4% of the potential sex partner population. This is a realistic calculation based on current data.” They add that given the prevalence of undiagnosed acute HIV infection, “HIV-uninfected individuals who try to serosort may be more likely to become HIV infected than if they had not tried to serosort in the first place.”