Seroepidemiology of herpes simplex virus type 1 and 2 in pregnant women in Switzerland: an obstetric clinic based study

Objective: To assess the seroprevalence of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) IgG antibodies and the seroincidence of HSV-1 and HSV-2 infections in pregnant women attending the maternity clinic of the University Hospital Lausanne.

Study design: Blood samples from 1030 women were taken at the usual pregnancy visit in the first trimester to assess the prevalence rate of IgG antibodies against HSV-1 and HSV-2 using a type-specific assay. A second blood sample was taken 6-8 weeks postpartum from returning women who were seronegative for HSV-2 or HSV-1 to assess the incidence of seroconversion (primary infection).

Results: The seroprevalence rates were 79.4% (95% CI: 76.9-81.9) for HSV-1 and 21.2% (18.7-23.7) for HSV-2 in women 14-46 years old. Type-specific serostatus patterns were as follows: 17.3% HSV-1/-2: +/+, 62.1% HSV-1/-2: +/-, 3.9% HSV-1/-2: -/+, 16.7% HSV-1/-2: -/-. Two hundred and sixty five women (59 of the 212 seronegative for HSV-1 (27.8%) and 265 of the 812 seronegative for HSV-2 (32.6%)) returned to the outpatient clinic for the post-delivery check and a second blood sample was obtained. One HSV-1 seroconversion was detected (HSV-1 seroconversion rate 2.4%/100 patient × year (95% CI: 0.06-13.4)) in a patient who had symptoms compatible with primary genital herpes. No HSV-2 seroconversion was detected (HSV-2 seroconversion rate: 0/100 patient × year (97.5% one-sided CI: 0-2)).

Conclusion: Compared to a previous population-based study, our study results suggest a rise in the prevalence of HSV-2 among pregnant women in Switzerland. The low incidence of seroconversion detected during pregnancy is consistent with the very low reported incidence of neonatal herpes in Switzerland.

Condensation: This study in a public hospital in Western Switzerland suggests an increasing prevalence of HSV-2, but a low incidence of primary infections in women of childbearing age.