Partner age difference and sociodemographic correlates of herpes simplex virus type 2 seropositivity: A community-based study in South India.

Sir,

Herpes simplex virus 2 (HSV-2) is one of the most prevalent sexually transmitted infections worldwide and is the leading cause of genital herpes and genital ulcer disease.[1] Studies have found that the seroprevalence of HSV-2 is lowest in Asia.[2] Age-disparate relationships (partner age difference of at least 5 years) have been shown to increase the risk of HIV and HSV-2 infections in sub-Saharan Africa in rural Zimbabwe and Uganda, where the prevalence of HIV/HSV-2 has been shown to be higher among women in age-disparate relationships.[345] Although past studies have explored numerous predisposing factors for HSV-2 infection, there is a paucity of data that explores the age difference between partners as a risk factor for HSV-2 infection in India. This study examined the role of age-disparate relationships in HSV-2 infection in South India.

The study was conducted in Mysore by the Public Health Research Institute of India (PHRII) in collaboration with partners from Florida International University. A type-specific enzyme-linked immunosorbent assay (ELISA) test was used to detect HSV-2 (Focus Diagnostics HerpeSelect® 2 ELISA Immunoglobulin G [IgG], Focus Technologies, Cypress, CA, USA) antibodies according to manufacturer's instructions. The laboratory where the HSV-2 testing was being conducted was overseen by a National Accreditation Board for Testing and Calibration Laboratories-accredited laboratory in Mysore to ensure that all the standard laboratory procedures were followed. Out of 351 individuals enrolled, 176 were women (50.14%), aged at least 25 years (77.8%), educated (≥1 year of schooling) (90.6%), married (96.3%), Hindu by religion (94.9%), and lived in urban areas (62.7%). Of the 351 individuals, 9.4% (95% confidence interval [CI]: 6.3%, 12.5%) had HSV-2 IgG antibodies. This study highlights an overlooked predictor of HSV-2 infection, i.e., age difference between partners.

The average age difference of the study participants with their sexual partner was 5.8 years (range: 0–25 years). The prevalence of HSV-2 infection was highest among individuals who had an age difference of 11–25 years (17.9%), followed by those with 6–10 years (13.9%) and 1–5 years (4.4%) with their sexual partner. The odds of HSV-2 infection increased among the study participants with an increase in the age difference with their sexual partner (odds ratio [OR]: 1.07, 95% CI: 1.02, 1.12). These odds remained significant after adjusting for sociodemographic variables, risky sexual behaviors, history of stress, and use of birth control (adjusted OR [aOR]: 1.22, 95% CI: 1.06, 1.40). The odds of HSV-2 infection was significantly lower among Hindus (9%) as compared to nonHindus (16.7%) (aOR: 0.19, 95% CI: 0.04, 0.84). Increasing age difference between sexual partners was associated with factors such as lower levels of condom use, increased frequency of sex, and long-lasting relationships.[6] These behavioral characteristics may be associated with higher rates of HIV transmission.[6] It is plausible that the same mechanism and factors can explain the increased odds of HSV-2 with increasing age difference between sexual partners. More research is needed to investigate the mechanisms seen in HIV transmission with respect to HSV-2 infection.

Despite several limitations (potential information bias and misclassification of HSV2 status, cross-sectional analysis, and nonprobability sampling), this study presents the first data (to our knowledge) which suggests that an increasing age difference between partners can predict HSV2 infection in South India, a phenomenon which is commonly observed with HIV. It is necessary to further explore the findings of this study in a larger population to ascertain the possible adverse effects of an increasing age difference between partners associated with HSV-2 infection and the potential social and medical implications.

Financial support and sponsorship

Abraham Degarege was supported by Florida International University Dissertation Year Fellowship. Makella Coudray and Purnima Madhivanan were supported by the National Institutes of Health grant (R15AI28714-01). Caitlyn Placek was supported by the Global Health Equity Scholars Training Grant from Fogarty International Center at the National Institutes of Health (R25 TW009338). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health or Florida International University.

Conflicts of interest

There are no conflicts of interest.