Monitoring Sexually Transmitted Infection-Associated Pathogens in Municipal Wastewater in Japan

Sexually transmitted infections (STIs) represent a significant global public health challenge, and the limitations of clinical diagnostics, such as under-reporting and incomplete geographic coverage, have highlighted the potential of wastewater-based epidemiology (WBE) as a complementary, population-level approach for monitoring STI prevalence and trends. This study aimed to demonstrate the feasibility of a WBE for the surveillance of STI pathogens within a community. Wastewater samples (n = 106) were collected once per week over a one-year period from two wastewater treatment plants in Japan. These samples were tested for Chlamydia trachomatis, Treponema pallidum, Neisseria gonorrheae, herpes simplex virus-2 (HSV-2), and human papillomavirus-16 (HPV-16) using the highly sensitive EPISENS-M method. C. trachomatis and HPV-16 were detected with high positive ratios, 90.6% and 74.5%, respectively, while other targets were rarely quantified in wastewater samples, suggesting they are more prevalent than other STI pathogens in the community. No positive correlations were observed among concentrations of all tested pathogens in the wastewater and reported clinical cases, apart from C. trachomatis, which exhibited a low positive correlation (Spearman’s ρ = 0.13), suggesting a potential under-reporting due to asymptomatic infections. This study demonstrated the potential of WBE for monitoring disease trends associated with individual STI pathogens, emphasizing its role as a valuable complementary tool for population-level surveillance and public health monitoring.