Noroviruses, the leading cause of nonbacterial acute gastroenteritis outbreaks, are widely detected in wastewater worldwide and reflect community-level viral circulation. These RNA viruses exhibit high mutation and recombination rates, favoring the emergence of novel variants with epidemiological relevance. In this study, wastewater-based epidemiology was applied to monitor the circulation of norovirus genogroups GI and GII in raw sewage samples collected biweekly throughout 2024 from a wastewater treatment plant serving the Metropolitan Region of Rio de Janeiro, Brazil. In parallel, the analytical performance of a commercial RT-qPCR kit was evaluated in comparison with an in-house RT-qPCR protocol for norovirus detection and quantification. A total of 24 samples were concentrated by ultracentrifugation, and viral nucleic acids were extracted using the Quick-DNA/RNA™ Viral MagBead kit. Norovirus GI and GII were detected and quantified using both the IBMP Biomol Rotavirus and Norovirus Kit and in-house assays. The IBMP kit showed higher detection rates for GI (54.2%) and GII (100%) compared with the in-house protocol (20.9% and 70.8%, respectively), as well as higher median viral concentrations for both genogroups. GI (5.8 ± 0.7 vs. 4.8 ± 0.2 log10 gc µL-1) and GII (7.1 ± 0.7 vs. 6.6 ± 0.8 log10 gc µL-1). Molecular characterization based on partial ORF1 (RdRp) and ORF2 (VP1) regions identified genotypes GII.17P17, GI.3P3, and GI.3P13, indicating the environmental circulation of globally disseminated strains previously associated with outbreaks. Overall, these findings support the applicability of wastewater-based surveillance for monitoring norovirus genotype circulation and highlight the usefulness of a commercial RT-qPCR assay for sensitive detection and quantification of noroviruses in environmental samples.
Moura et al. (Wed,) studied this question.