About AIDS Heard the notion that a “top” – the insertive partner in anal intercourse – is not at particularly high risk for HIV infection? That’s part truth, part myth. Turns out, lots of HIV still may be present in rectal secretions despite the bottom’s viral load being low or even “undetectable.”
Standard viral load measures HIV levels only in the blood. One treatment goal is to reduce VL, preferably to undetectable (under 200 HIVs per milliliter of blood, or below “countability”). Yet, previous research is clear: A VL reduction in the blood does not result in an equal reduction in semen or other body fluids. (That’s one reason for still emphasizing condom use by HIV-positive guys with undetectable VL who may think they are not infectious.)
Somewhat like vaginal tissues, the rectum’s mucosal lining exudes secretions; and like vaginal fluids, rectal secretions contain HIV. Until rather recently, however, medical science didn’t overtly address a top’s potential infection through anal sex except by blood being rectally present, e.g., from damaged capillaries. (Nothing new in that: Discussing almost anything related to gay sexual behaviors is significantly taboo and politically dangerous to one’s funding.)
Now, University of Washington research indicates that among HIVers in treatment, the HIV present in one’s rectal secretions may substantially exceed those in his blood. Even when participants had undetectable VL (fewer than 200) in blood, their semen averaged 500% higher VL and their rectal secretions a whopping 20 times as much.
In a nutshell, anal top-guys may be at greater risk of HIV infection than previously believed. That emphasizes the need for condoms in anal sex, even if only the bottom is HIV positive.
(For details, see The Journal of Infectious Disease, 190[1]:156-61; presented at CROI, February 2005.)
This article appears in March 18 • 2005.