Does frequency of genital herpes recurrences predict risk of transmission? Further analysis of the valacyclovir transmission study.

BACKGROUND: The benefit of suppressive antiviral therapy for reducing the risk of herpes simplex virus (HSV)-2 transmission to sex partners may be enhanced if persons at high risk for transmission can be identified.

OBJECTIVE: To determine whether frequency of genital herpes recurrences is associated with increased risk of HSV-2 transmission.

METHODS: Analysis of recurrence frequency and shedding frequency (subset) among participants in a randomized controlled trial of valacyclovir 500 mg qd versus placebo for reducing the risk of HSV-2 transmission.

RESULTS: Overall, 1484 monogamous HSV-2-serodiscordant couples participated and 41 HSV-2 transmissions occurred during the 8-month trial; 40 were able to provide a history of recurrence frequency. The rate of recurrences per year before study entry did not differ between source partners who transmitted and those who did not, 4.8 versus 5.1, respectively. Similarly, the mean frequency of recurrences observed during the study also did not differ among those who transmitted versus those who did not for placebo recipients (4.4 vs. 4.8) or valacyclovir recipients (1.4 vs. 1.3). Among the 40 source partners who transmitted HSV-2, 8 of 27 placebo recipients and 7 of 13 valacyclovir recipients had no recurrences during the study.

CONCLUSION: Clinical assessment of HSV-2 disease severity as defined by the frequency of genital herpes recurrences does not predict the risk of transmission to sexual partners. Though patients with frequent recurrences are most likely to benefit clinically from suppressive therapy, frequency of recurrences is not helpful in identifying persons who are most likely to transmit HSV-2.