Incident HSV-2 Infections Are Common Among HIV-1-discordant Couples

Herpes simplex virus type 2 (HSV-2) is the most common cause of genital ulcer disease in the world, and sub-Saharan Africa bears a heavy burden of infections [1, 2]. Manifestations of HSV-2 infection range from asymptomatic or nonulcerative symptoms to periodic outbreaks of painful ulcers [3, 4]. There is a strong synergistic relationship between HSV-2 and human immunodeficiency virus type 1 (HIV-1), resulting in greater shedding and elevated infectiousness of both viruses [5–10]. HSV-2 can be managed with episodic antiviral medication (eg, acyclovir, valacyclovir, or famciclovir) to abort or reduce the duration of outbreaks or with daily suppressive treatment to prevent outbreaks and reduce asymptomatic viral shedding [11]. Although suppressive HSV-2 treatment reduces plasma HIV-1 viral load, a recent randomized trial failed to show a benefit of suppressive acyclovir therapy in reducing HIV-1 transmission [12]. However, daily suppressive therapy with valacyclovir decreases herpes transmission to sexual partners [13]. Prevention of new HSV-2 infections may be an effective HIV-1 prevention strategy, particularly among HIV-1-discordant couples in which either member of the couple is HSV-2 seronegative. While estimates vary due to population characteristics, 10%–25% of new HIV-1 infections in sub-Saharan Africa occur in HIV-1-discordant couples [14–17]. In this region, HSV-2 prevalence in one or both members of HIV-1-discordant couples is as high as 80% [18]. Yet there is limited knowledge about the timing and risk factors for HSV-2 acquisition in this high-risk population. Given the importance of HSV-2 in mediating HIV-1 transmission, we sought to better understand HSV-2 transmission in HIV-1-discordant couples by investigating its prevalence and incidence among stable HIV-1-discordant heterosexual couples in Nairobi, Kenya.