Using Wastewater-Based Epidemiology to Detect and Monitor Sexually Transmitted Infections: Chlamydia and Gonorrhea

Wastewater-based epidemiology (WBE) enables population-level health monitoring, offering a high-throughput and cost-effective complement to traditional surveillance methods. Recent modeling has identified STIs as promising targets for wastewater surveillance. However, significant gaps remain in understanding scalability across different population sizes, integrating targeted and nontargeted approaches, and developing data actionability. This study addresses these gaps through comprehensive STI surveillance at two distinct scales: a centralized water reclamation facility (WRF) serving 4.8 million people and residential buildings housing 7500 residents. Wastewater samples were analyzed using droplet digital PCR (ddPCR) for targeted detection of Neisseria gonorrheae and Chlamydia trachomatis and shotgun metagenomic sequencing of WRF samples for comprehensive pathogen characterization. We demonstrate a bacterial activity level system, adapted from CDC viral surveillance protocols, that provide clear, actionable categories for public health response. Metagenomic analysis identified seven different STI-causing pathogens (Hepacivirus hominis, Human alphaherpesvirus 1 and 2, Haemophilus ducreyi, Neisseria meningitidis, Treponema pallidum, and Neisseria gonorrheae). This work contributes to the growing evidence supporting STI wastewater surveillance as a valuable complement to clinical surveillance. The combined targeted and metagenomic approaches demonstrate potential applications for monitoring community-level STI patterns and informing public health response strategies.