Prevalence of sexually transmitted infections and associated risk factors among female sex workers in Guinea-Bissau

Objective To estimate the prevalence of the curable sexually transmitted infections (STIs) Chlamydia trachomatis, Neisseria gonorrhoeae, Mycoplasma genitalium, Trichomonas vaginalis and Treponema pallidum, to identify associated risk factors and to assess ciprofloxacin resistance in N. gonorrhoeae-positive specimens among female sex workers (FSWs) in Guinea-Bissau.Methods For this cross-sectional study, FSWs were recruited from October 2014 to May 2019. A questionnaire on STI risk factors was completed by the study participants, and the women were asked to provide a vaginal swab for nucleic acid amplification tests for C. trachomatis, N. gonorrhoeae, M. genitalium, T. vaginalis (Aptima, Hologica), as well as a blood sample for T. pallidum serological testing and discriminatory HIV-testing. The prevalence of STIs was determined, and multivariate logistic regression was used to identify STI risk factors.Results The study included 467 women. The prevalence of current infection with any curable STI was 46.7%, and the most common pathogen was T. vaginalis (26.3%), followed by M. genitalium (21.9%), C. trachomatis (11.8%), N. gonorrhoeae (10.1%) and T. pallidum (2.8%). The proportion of asymptomatic infections among the diagnosed STIs was 61.8%, 61.5%, 55.3%, 55.3% and 52.2% for C. trachomatis, T. pallidum, N. gonorrhoeae, T. vaginalis and M. genitalium, respectively. The prevalence of the gyrA S91F mutation conferring ciprofloxacin resistance in N. gonorrhoeae-positive specimens was 84.0%. Significant risk factors for having a curable STI were age and HIV-1 infection, while use of female condoms was a protective factor.Conclusion This study demonstrated that the prevalence of curable STIs was high among FSWs in Guinea-Bissau during the study period, indicating an unmet need for STI services. Moreover, the results indicated that symptomatic treatment might be insufficient, highlighting a need for periodic aetiological testing to facilitate detection of asymptomatic as well as symptomatic STIs to stop ongoing transmission.