Seroincidence of Human Herpes Virus 2 Among Ante-natal Clinic Attendees in Benin, Nigeria

Background: Human Herpes Virus 2 (HSV-2) infection has been shown to be significantly associated with several obstetric complications, especially if the infection occurred during the pregnancy. Advocacy for policy formulation and the design of interventions requires local data on the risk factors for incident HSV-2 infection.
The aim of this study is to assess HSV-2 sero-incidence among pregnant women in Benin and the effect of socio-demographic factors, HIV status, and HSV-1 status.
Study Location, Design and Duration: Pregnant women attending ante-natal clinic in University of Benin Teaching Hospital and Central Hospital, Benin were prospectively recruited. A cross-sectional study was done and baseline data, obtained. The HSV-2 seronegative participants were followed up till the last clinic appointments [the closest appointment to their expected delivery dates (EDD)]. The study took place between November 2011 and December 2012.
Methods: On recruitment a structured self-administered questionnaire was used to capture their socio-demographic data. Obstetric data was obtained from the patients’ case notes. Their HSV-1 and HSV-2 serostatuses were determined using an HSV glycoprotein G-based type-specific ELISA technique. Their HIV statuses were also determined. All those who were seronegative for HSV-2 were retested for HSV-2 six months later and/or on their last clinic appointment before the EDD. Incidence rates were calculated per person-years. Data analysis utilized SPSS version 16 software.
Results: Out of the 674 participants, 315(46.8%) were HSV-2 seropositive while 359 (53.2%) were seronegative. 15.9% (57) of the HSV-2 sero-negative ones were lost to follow-up, giving a response rate of 84.1%. Seroincidence rate was found to be 17.9 per 100 person-years. There was significant association of seroincidence with younger reproductive age groups, unmarried status, and education below secondary level. Relative Risk (RR) and Incidence rate ratio (IRR) of HSV-2 infection among the HIV-infected cohort were 55.15 [95%CI:17.0-179.1] and 72.37 [95% CI:71.11-73.63] respectively. The RR and IRR among the HSV-1-seronegative cohort were 1.43 [95%CI:0.64-3.17] and 11.62 [95%CI:9.60-13.64] respectively.
Conclusion: Seroincidence rate of HSV-2 infection among pregnant women in Benin was found to be 17.9 per 100 person-years. Positive HIV status, young age, unmarried status, and low education level were indicators of increased risk of incident HSV-2 infection.