Environmental prevalence of enteric viruses across the covid-19 pandemic: A three-year monitoring study.

Enteric viruses are continuously excreted in high concentrations in human feces and are disseminated into aquatic environments through treated and untreated wastewater, much of which is ultimately discharged into coastal marine waters. Environmental surveillance of these pathogens may therefore reflect their circulation in human populations and serve as an early-warning tool for the emergence of new viruses or variants, as well as increased transmission of existing ones. In this study, we investigated the occurrence and molecular diversity of major gastroenteric viruses - adenovirus, noroviruses, rotavirus - together with other enteric viruses with variable clinical relevance, in coastal marine waters of Campania Region (Southern Italy). Viral prevalence was evaluated according to season, sampling year, and type of wastewater discharge. A total of 500 marine water samples were collected, of which nearly half (44.0%) tested positive for at least one viral target. Viral detection rates varied across years, presumably influenced by the epidemiological dynamics associated with the COVID-19 pandemic. Notably, phylogenetic analyses revealed that most environmental viral sequences were identical or closely related to strains previously identified in human clinical cases from the same geographical area, supporting a strong epidemiological link between human infections and environmental contamination. Overall, these findings underscore the value of integrated environmental surveillance for public health risk assessment within a One Health framework.