Human Immunodeficiency Virus in Semen and Plasma: Investigation of Sexual Transmission Risk Behavioral Correlates

Risks for sexually transmitted HIV may be related to concentrations of virus detected in semen and previous research shows a small to moderate association between viral load in blood and semen. This study examined the association between viral load in semen and plasma in a community sample of HIV-infected men and is the first study to examine semen viral load in relation to sexual transmission risk behaviors. A sample of 44 HIV-positive men recruited from community service agencies provided semen, blood, and urine samples and completed clinical interviews assessing health and behavior. We failed to find an association between viral load in semen and plasma, Spearman r5 0.07, p. 0.1. When restricted to participants with detectable virus in semen and plasma, the correlation remained nonsignificant, r 5 20.16, p. 0.1. Men who had higher se-men viral loads relative to their plasma viral load were distinguished by having engaged in significantly higher rates of unprotected intercourse as the insertive sex partner in the previous 3 months. Semen viral load was not, however, related to recent or current sexually transmitted infections (STIs). This study is among the first to examine sexual transmission risk behaviors as marker for HIV infectiousness. Results caution against in-ferring sexual transmission infectiousness based on plasma viral load and suggest that HIV-positive men who practice higher rates of insertive intercourse may be more infectious even in the absence of other STIs. 169