Forced vaginal sex and genital immune correlates of HIV risk: a prospective study of female sex workers in Kenya.

BACKGROUND

The likelihood of HIV acquisition is increased following forced vaginal sex. This relates in part to epidemiological and behavioural factors; however, the biological effects of forced vaginal sex, including impacts on immune parameters linked to HIV susceptibility, are poorly understood. Here, we examine biological mediators of HIV susceptibility among female sex workers (FSWs) in Nairobi, Kenya, who recently experienced forced vaginal sex.

METHODS

The Maisha Fiti study was a longitudinal cohort study of FSWs from Nairobi, Kenya. At up to three visits, HIV-uninfected participants completed a detailed sociodemographic survey in which they were asked if they had experienced forced vaginal sex in the past 7 days. Proinflammatory cytokines and soluble E-cadherin (sE-cad), a biomarker of epithelial barrier disruption, were quantified in cervico-vaginal secretions by multiplex immunoassay. Associations between recent forced sex and genital inflammation were assessed longitudinally in a mixed-effects regression model adjusted for potential confounders and within-participant correlation.

RESULTS

Of the 746 participants, 44 (6%) reported forced vaginal sex in the past 7 days at baseline, with strong evidence of associations with adverse childhood experiences (p<0.001), mental health issues (p<0.001) and poverty (p=0.02). Recent forced sex was associated with increased genital inflammation (adjusted OR (aOR)=2.74; 95% CI 1.33 to 5.68; p<0.01) independent of previously defined confounders but was not associated with altered levels of sE-cad (p=0.56). Neither recent consensual sex (aOR=0.94, 95% CI 0.63 to 1.40, p=0.76) nor forced sex within the past 6 months, excluding the past 7 days (aOR=0.93, 95% CI 1.21 to 5.42, p=0.70), was associated with genital inflammation.

CONCLUSIONS

Cervicovaginal inflammation is increased in FSWs for at least a week after forced vaginal sex. This has important implications for HIV prevention programmes that provide care to women experiencing gender-based violence. Further studies are needed to understand the specific timing of proinflammatory cytokine release following forced vaginal sex.