HIV-negative gay men are much less likely to engage in unprotected anal intercourse with an HIV-positive partner if they perceive him to have a detectable viral load, the National AIDS Treatment Advocacy Project reports. Australian researchers looked at risk behavior in an ongoing study of 76 serodiscordant couples (meaning that one was HIV positive and the other HIV negative) and presented their findings at the 7th International AIDS Society Conference on HIV Pathogenesis, Treatment and Prevention (IAS 2013) in Kuala Lumpur.

Fifty-six (74 percent) of the HIV-positive partners had an undetectable viral load at the beginning of the study, and the remainder had a detectable viral load. Meanwhile, sixty-one (80 percent) of the HIV-negative partners believed their partner had an undetectable viral load, while the remainder believed their partner had a detectable viral load or didn’t know their viral load. This left a difference of five HIV-negative men who were either mistaken or uninformed about their partner’s viral load.

Fifty-five (72 percent) of the HIV-negative partners reported unprotected anal intercourse (UAI) with their partner. Among them, 48 (63 percent of the study group) reported insertive UAI—or being the top—while 32 (45 percent) reported receptive UAI (bottoming) without ejaculation and 19 (25 percent) reported receptive UAI with ejaculation. In other words, the HIV-negative partners were more likely to be the top during condomless anal sex.

Of the 61 HIV-negative men who thought their partner had an undetectable viral load, 49 (80 percent) had UAI in the previous three months. Of the 15 HIV-negative men who thought their partner had a detectable viral load or did not know his viral load, six (40 percent) had UAI in the previous three months.

Believing that a partner had a detectable viral load lowered the likelihood of UAI by 84 percent.

To read the NATAP report, click here.

To read the conference abstract, click here.