Introduction World Health Organisation global estimates for sexually transmitted infections (STI) stand at 448 million new cases per year with the greatest burden occurring in sub-Saharan Africa. We assessed prevalence and correlates of herpes simplex virus type 2 (HSV-2), bacterial vaginosis (BV), gonorrhoea, syphilis, chlamydia and HIV infection among Kenyan women 18–34 years of age screened for a contraceptive vaginal ring study

Methods Women provided socio-demographic, medical information, and underwent real-time rapid HIV testing, STI testing using vaginal swabs and pelvic examinations. Log-binomial regression model was used to compute adjusted prevalence ratios (PR).

Results Out of 463 women screened, 457 were included in the analysis. Median age was 25 IQR (21-28) and 67% had completed primary education. Overall, 71.3% tested positive for any STI, including HIV. Prevalence of HSV-2, BV, and HIV were 54.9%, 30.0% and 14.5% respectively; 18.1% were co-infected with all STIs. STI prevalence increased with age and peaked among those 30–34 years (PR=1.26; 95% CI, 1.06, 1.48). Early age at first sex (<14 years) was associated with a 27% increase in STI prevalence compared to those who initiated sexual activity at ages 17–19 (PR=1.27; 95% CI, 1.07, 1.51). History of transactional sex, and sexual intercourse in the last 7 days were associated with a prevalent STI (PR=2.05; 95% CI, 1.07, 3.92) and (PR=1.17; 95% CI, 1.01, 1.36), respectively. Women reporting one lifetime sexual partner were 30% less likely to test positive for any STI compared to women with 4 or more lifetime sexual partners (PR=0.70; 95% CI, 0.54, 0.92).

Conclusion Multiple prevention strategies, including dual protection from pregnancy and STIs, are needed in this setting.