Effect of Herpes Simplex Suppression on Incidence of HIV Among Women in Tanzania

Given that infection with herpes simplex virus type 2 (HSV-2) is associated with an increased risk of acquiring HIV, the current study tested whether therapy to suppress HSV-2 might reduce the risk of HIV acquisition.

The subjects of the study were female workers, ages 16-35, at recreational facilities in northwestern Tanzania. The women underwent interviews and serologic testing for HIV and HSV-2. The researchers enrolled women who were HIV-seronegative and HSV-2-seropositive in a randomized, double-blind, placebo-controlled trial of suppressive treatment with acyclovir (400mg twice daily).

The women attended mobile clinics every three months for a follow-up period of 12 to 30 months, depending on date of enrollment. Incidence of HIV infection was the primary outcome. The researchers used a modified intention-to-treat analysis; data for participants who became pregnant were censored. A tablet count at each visit was used to assess adherence to treatment.

In all, 821 women participated and were randomly assigned to receive acyclovir (400 women) or a placebo (421 women). Eighty-three percent (n=679) completed follow-up; mean follow-up was 1.52 years for the acyclovir group and 1.62 years for the placebo group.

HIV infection incidence was 4.27 per 100 person-years (27 women in the acyclovir group, 28 in the placebo group). There was no overall effect of acyclovir on the incidence of HIV (rate ratio for the acyclovir group, 1.08; 95 percent confidence interval, 0.64-1.83). Median adherence was estimated at 90 percent. At six, 12 and 24 months, genital HSV was detected in a similar proportion of women in the two groups. There were no serious adverse events attributable to acyclovir.

"These data show no evidence that acyclovir (400mg twice daily) as HSV suppressive therapy decreases the incidence of infection with HIV," the authors concluded.