Spatiotemporal Dynamics of Norovirus and Microbial Source Tracking Markers across Rivers of Midwest Area, South Korea

Norovirus is a major cause of acute gastroenteritis worldwide and is frequently transmitted through contaminated water. This study examined the prevalence of norovirus genogroups I (GI) and II (GII) and their associations with human-specific microbial source tracking (MST) markers in river water from the Daejeon and Sejong areas, South Korea. A total of 108 water samples were collected monthly from nine sites along the Geum River system. Physicochemical parameters including water temperature, pH, total dissolved solids, and electrical conductivity were evaluated. Bacterial indicators including coliforms and Escherichia coli were consistently detected in the river samples. Nested RT-PCR detected NoV GI in 68.5% and NoV GII in 38.9% of samples, indicating persistent contamination throughout the study period. MST markers (Bacteroides HF183, CPQ_056, and CPQ_064) showed mean concentrations of 3.43, 4.75, and 3.92 log gene copies/100 mL, respectively. Both norovirus genotypes were positively correlated with MST markers and TDS, while CPQ_056 and CPQ_064 were negatively associated with water temperature. These findings demonstrate the persistence of norovirus in riverine environments and support MST-based monitoring as a valuable framework for tracking human fecal contamination and improving water quality management.