HSV-2 infection (HSV-2 infection causes a form of herpes infection)
appears to double or triple the risk of HIV infection by creating
lesions through which the virus can easily enter the body. It also
increases the ability of a person who is infected with the HIV and
HSV-2 to infect others.

About 80-90% of HIV-positive individuals and 50% of HIV-negative
women are HSV-2 infected. Because of the link between HSV 2 infection and HIV infection there has been considerable interest in testing whether HSV-2 suppressive treatment (treatment that would reduce the ability of HSV-2 to multiply in the body) in HIV-negative individuals can reduce their risk of HIV acquisition. Studies are also looking at the possibility of the use of HSV-2 suppressive therapy reducing the ability of HIV positive individuals to infect their sexual partners. Results to date have been disappointing. Two large studies failed to find any protective effect of daily HSV suppression therapy in HIV- negative women or men who have sex with men. A third study HIV- discordant partnerships (one partner is HIV negative and another is HIV positive) where the HIV-positive partner is coinfected with HSV- 2, is ongoing in sub-Saharan Africa and expected to report in February 2009.