Herpes simplex virus type-2 (HSV-2) is the primary cause of genital ulcers and one of the most prevalent sexually transmitted diseases worldwide. Consistently, over 30 studies have found HSV-2 infection to be a risk factor for HIV acquisition with an overall relative risk of 2.1 in the studies that demonstrated HSV-2 preceded HIV infection. A recent study of HIV-discordant couples from Rakai, Uganda, has shown that at all levels of HIV viral load in the HIV-positive partner, HSV-2 infection in the susceptible partner increased the per-contact risk of acquisition of HIV five-fold, and GUD in the HIV-source partner increased the per-contact risk of HIV transmission five-fold. As strong as these epidemiological data are, an intervention trial is required to define the clinical and public health significance of these findings.

This trial will directly answer the extent to which HSV-2 infection increases infectiousness of HIV/HSV-2 co-infected persons and the relative reduction in HIV transmission among HSV-2 seropositive persons treated with daily suppressive antiviral therapy. Acyclovir has an acceptable safety profile for widespread STD treatment and is inexpensive, well-tolerated, and episodic and long-term suppressive therapy has not been associated with increased acyclovir resistance. Given high HSV-2 seroprevalence in HIV-infected persons (70-80%) and high HIV incidence in populations with high prevalence of HSV-2 infection worldwide, this approach could have great public health importance by providing a safe, acceptable, and cost-effective method to reduce HIV transmission among HIV-infected persons who are also HSV-2 seropositive.

Sites that have enrolled couples in this study include: Johannesburg (2 sites) and Cape Town, South Africa; Gaborone, Botswana; Kitwe/Ndola and Lusaka, Zambia; Nairobi, Kisumu, Eldoret and Thika, Kenya; Moshi, Tanzania; Kampala, Uganda; and Kigali, Rwanda.