Variability of Pepper Mild Mottle Virus in Wastewater across the United States: A Review of Methodological, Environmental, and Demographic Drivers

Pepper mild mottle virus (PMMoV) has gained popularity as a biomarker of human fecal load in wastewater-based epidemiological studies. However, various factors influencing its concentration in wastewater have not been thoroughly investigated. This study analyzed 46 research studies reporting data across 360 sites in 34 states in the United States. The analysis showed high variability of PMMoV concentrations in domestic wastewater across different regions of the U.S., with average wastewater PMMoV concentrations ranging between 3.6 log 10 genome copies (GC)/L and 10.3 log 10 GC/L. Sample preprocessing methods, type of collection site, and population demographics were predominant factors affecting wastewater PMMoV variability, whereas weather, seasonality, and sampling frequency were less impactful. The majority (99%) of the literature reflected urban or suburban wastewater, which reveals data and knowledge gaps from rural wastewater. The results of this study contribute to improving pathogen normalization practices and developing data-driven models for better prediction of future disease prevalence and transmission.