Treating herpes simplex 2 (HSV-2) in HIV-positive people does not reduce the risk of transmitting HIV to their sexual partners, according to study from University of Washington at Seattle and reported by MedPage Today. Preliminary data were presented at the 15th Conference on Retroviruses and Opportunistic Infections in 2008.

This line of research is in response to epidemiological and laboratory observations that having HSV-2 increased the risk of contracting HIV. Researchers reasoned that the converse would be true: that HSV-2 treatment could reduce the risk of HIV transmission.

The large, randomized and placebo-controlled clinical trial involved 3,408 African couples in which one partner was HIV positive (but not on medication) and had HSV-2. Results showed that treating HSV-2 with acyclovir (Zovirax) significantly reduced HIV viral load but did not prevent transmission of the virus to the other partner. Study authors concluded that a greater reduction in viral load would be needed to prevent transmission in serodiscordant couples.

In the study, 84 HIV transmission cases between partners were verified. Of those, 41 took acyclovir, while the others were in the placebo group.

Also of note: Acyclovir reduced the occurrence of herpes lesions, proving that the HIV transmission cases in the study did not stem from nonadherence to the HSV-2 treatment.