Prevalence and risk factors of Chlamydia trachomatis, Neisseria gonorrhoeae, Trichomonas vaginalis and other sexually transmissible infections among women attending antenatal clinics in three provinces in Papua New Guinea: A cross-sectional survey

Background Papua New Guinea (PNG) is estimated to have among the highest prevalences of HIV and sexually transmissible infections (STIs) of any Asia-Pacific country, and one of the highest burdens of maternal syphilis globally. The prevalence of curable STIs, such as Chlamydia trachomatis (CT), Neisseria gonorrhoeae (NG) and Trichomonas vaginalis (TV), among pregnant women in PNG is relatively unknown. Methods: A cross-sectional bio-behavioural survey to investigate the epidemiology of CT, NG, TV and other STIs among pregnant women in three provinces of PNG was undertaken. Women aged 18-35 years attending their first antenatal clinic visit were invited to participate. Participants completed a short interview and provided self-collected vaginal specimens for CT, NG and TV laboratory-based nucleic acid amplification tests and a venepuncture specimen for laboratory testing for syphilis and Herpes simplex virus type-2 (HSV-2) serology. Routine antenatal assessment was conducted according to national guidelines, including HIV counselling and testing and point-of-care syphilis screening. Results: A total of 765 women were enrolled. Overall, 43% (95% confidence interval (CI): 39.2-46.4) had one or more of CT, NG or TV infection. CT was the most prevalent STI (22.9%, 175/765; 95% CI: 19.9-25.9), followed by TV (22.4%, 171/765; 95% CI: 19.4-25.4), and NG (14.2%, 109/765; 95% CI: 11.7-16.7). The prevalence of active syphilis was 2.2% (17/765; 95% CI: 1.2-3.3), HSV-2 was 28.0% (214/765; 95% CI: 24.8-31.2) and HIV, 0.8% (6/765; 95% CI: 0.2-1.4). Prevalences were highest among primigravid women, women aged