Seroprevalence and Vaginal Shedding of Herpes Simplex Virus Type 2 in Pregnant Adolescents and Young Women from Morelos, Mexico

Abstract

Adolescents and young people are particularly vulnerable to contracting STIs, including HSV-2; furthermore, vaginal shedding of HSV-2 during pregnancy can cause vertical transmission and neonatal herpes. To evaluate the seroprevalence of HSV-2 and vaginal HSV-2 shedding in adolescent and young pregnant women, a cross-sectional study was carried out in 496 pregnant women-adolescents and young women. Venous blood and vaginal exudate samples were taken. The seroprevalence of HSV-2 was determined by ELISA and Western blot. Vaginal HSV-2 shedding was assessed by qPCR of the HSV-2 UL30 gene. The seroprevalence of HSV-2 in the study population was 8.5% (95% CI 6-11), of which 38.1% had vaginal HSV-2 shedding (95% CI 22-53). Young women presented a higher seroprevalence of HSV-2 (12.1%) than adolescents (4.3%), OR = 3.4, 95% CI 1.59-7.23. Frequent alcohol consumption was significantly associated with HSV-2 seroprevalence, OR = 2.9, 95% CI 1.27-6.99. Vaginal HSV-2 shedding is highest in the third trimester of pregnancy, but this difference is not significant. The seroprevalence of HSV-2 in adolescents and young women is similar to that previously reported in other studies. However, the proportion of women with vaginal shedding of HSV-2 is higher during the third trimester of pregnancy, increasing the risk of vertical transmission.

Keywords: HSV-2; adolescent pregnancy; seroprevalence; vaginal shedding.

Figure 1

Seroprevalence and vaginal shedding of HSV-2. (A) The seroprevalence of HSV-2 in the study population was 8.5%, while vaginal HVS-2 shedding among seropositive women was 38.1%. The vaginal shedding of HSV-2 in young women was 87.5%, and in adolescents was 12.5%. (B) HSV-2 seroprevalence stratified by gestational age was 9.3% in the first trimester, 6.1% in the second trimester, and 11% in the third trimester, while vaginal shedding was 18.8% in the first trimester, 31.2% in the second trimester, and 50% in the third trimester.

Figure 2

Genital herpes incidence Mexican women, 2011–2021. The bars show the incidence of genital herpes in Mexican women between 2011 and 2021, stratified by age; global is all ages (10 to <65 years). The lines represent the trend line for each stratum. (Elaboration added, 2023, data from reference [20]).