Background Genital HSV-1 has surpassed HSV-2 as a cause of first episode genital herpes in high-income settings. To inform counseling messages regarding prevention of genital HSV-1 transmission, we assessed oral and genital shedding patterns among persons with laboratory documented first episode genital HSV-1 infection.

Methods Participants with virologic evidence of first episode genital HSV-1 infection self-collected oral and genital swabs for HSV PCR and completed symptom diaries for 30 days at 2 and 11 months after the first episode. Questionnaires about sexual practices were completed. Blood samples were collected at serial timepoints to assess antibody and cellular immune responses to HSV-1. HSV serostatus was determined using the HSV Western Blot, and those who were HSV seronegative at the time of enrollment had primary infection. The per-participant risk of oral and genital HSV-1 shedding during the first and second collection periods was determined.

Results Of 62 participants who completed both swabbing sessions, 42 (68%) were women and 36 (58%) had primary HSV-1 infection. Of 54 who responded, 44 (81%) had a sex partner of the opposite gender and 43 (80%) had a single partner within 4 weeks prior to symptom onset. Genital HSV was detected on 205 (12.2%) of 1684 days at 2 months and declined significantly to 92 (5.5%) of 1668 days at 11 months (RR=0.45, 95% CI=0.24–0.85). On days when genital HSV was detected, the median quantity was higher at 11 months (4.2 log10 copies/ml) as compared to 2 months (3.2 log10 copies/ml), p<0.0001). HSV was detected from the mouth on 4.1% of days and stable over the first year. Genital lesions were rare during both periods (104 (2.8%) of 3687 days).

Conclusion HSV-1 genital shedding is rapidly contained after the first year of genital HSV-1 infection. Genital HSV-1 shedding is relatively infrequent, but does persist, one year after first episode infection.

Disclosure No significant relationships.