Suppression of subclinical shedding of herpes simplex virus type 2 with acyclovir.

ABSTRACT

OBJECTIVE: To assess the effect of the antiviral drug acyclovir on the frequency of subclinical shedding of herpes simplex virus (HSV) in the genital tract. DESIGN: A double-blind, placebo-controlled, crossover clinical trial. SETTING: A university-based virology research clinic. PATIENTS 34 women with herpes simplex virus type 2 (HSV-2) antibody only and genital herpes of less than 2 years' duration. INTERVENTION Participants were randomly assigned to receive either acyclovir, 400 mg twice daily for 70 days, followed by a 14-day washout period, and then placebo for 70 days, or the study medications in the reverse order. MEASUREMENTS Women collected daily genital swabs of the vulvar, cervicovaginal, and perianal areas for HSV culture, maintained a diary of genital lesions, and were examined at the time of recurrences. RESULTS: In an intent-to-treat analysis of the initial treatment period, 15 of the 17 women who received placebo and 3 of the 17 women who received acyclovir had at least 1 day of subclinical shedding (P < 0.001). Among the participants who received placebo, subclinical shedding occurred on 64 of 928 (6.9%) days compared with 3 of 1057 (0.3%) days among the participants who received acyclovir (P < 0.001). The relative risk for subclinical shedding was 0.09 (95% CI, 0.03 to 0.35) for the women who received acyclovir compared with the women who received placebo. In a paired analysis of 26 women who completed both arms of the study, acyclovir therapy was associated with a decrease in the frequency of subclinical shedding; subclinical shedding occurred on 83 of 1439 (5.8%) days with placebo, and on 6 of 1611 (0.37%) days with acyclovir (P < 0.001)--a 94% reduction. The frequency of subclinical shedding was reduced at all anatomic sites and in all patients. CONCLUSIONS: Daily therapy with oral acyclovir suppresses subclinical shedding of HSV-2 in the genital tract, suggesting that studies to evaluate the use of acyclovir in preventing HSV-2 transmission are warranted.