RT Journal Article SR Electronic T1 HSV-2 incidence by sex over four age periods to age 38 in a birth cohort JF Sexually Transmitted Infections JO Sex Transm Infect FD BMJ Publishing Group Ltd SP 243 OP 245 DO 10.1136/sextrans-2013-051235 VO 90 IS 3 A1 Nigel Dickson A1 Antoinette Righarts A1 Thea van Roode A1 Charlotte Paul A1 Janette Taylor A1 Anthony L Cunningham YR 2014 UL http://sti.bmj.com/content/90/3/243.abstract AB Objectives To examine herpes simplex virus type 2 (HSV-2) incidence over four periods to age 38 in a birth cohort, and to compare risks for men and women, taking into account sexual behaviour. Methods At ages 21, 26, 32 and 38, participants in the Dunedin Multidisciplinary Health and Development Study were invited to provide serum for HSV-2 serology, and information on sexual behaviour. HSV-2 incidence rates were calculated for four age periods, and comparisons made by sex and period, taking into account number of sexual partners. Results By age 38, 17.3% of men and 26.8% of women had ever been seropositive for HSV-2. Incidence peaked for women from age 21 to 26 (19.1 per 1000 person-years) and men from age 26 to 32 (14.1 per 1000 person-years); it fell markedly for both from age 32 to 38 (5.1 and 6.8 per 1000 person-years for men and women, respectively). Overall risk was significantly higher for women: adjusted incidence rate ratio 1.9 (95% CI 1.4 to 2.7); the sex difference was most marked from age 21 to 26 (3.4, 95% CI 1.9 to 6.3). Conclusions Our findings are consistent with a greater biological susceptibility to HSV-2 among women, and with the increasing risk to the early/mid-20s for women and late 20s/early 30s for men, being driven by an increasing pool of prevalent infection. The reduced risk in the mid-30s is consistent with declining infectivity of long-term prevalent infections.