Epidemiological surveillance of astrovirus, norovirus, rotavirus, and enterovirus in sewage (2022–2023) in Giza, Egypt

The majority of people with enterically transmitted viruses excrete significant amounts of the virus in their feces for several days or weeks. Therefore, viruses causing diarrhea could be detected in the feces of infected persons and wastewater. In this study, the presence of human astrovirus (AstV), norovirus (NoV), rotavirus (RV), and enterovirus (EntV) was analyzed by real-time RT-PCR in raw sewage (<i>n</i> = 96), treated sewage (<i>n</i> = 96) and diarrheal stool samples (<i>n</i> = 200). Overall, 92.7% (89/96) of raw sewage samples and 48% (46/96) of treated sewage tested positive for at least one virus. The highest detection rates of the four viruses in raw sewage were observed in the winter season. Overall, the mean concentration of the four viruses was 7.3 log₁₀ in raw and 4.8 log₁₀ in treated wastewater, for a total removal of 34% of viral loads. In clinical samples, the most commonly detected virus was EntV followed by RV, NoV, and AstV. The mean concentrations of the four viruses in clinical samples ranged between 2.5 × 10¹ and 9.86 × 10⁷ GC/g. The results presented here demonstrated that the environmental surveillance of entric viruses in sewage is a useful tool for the study of their transmission dynamics in humans and their molecular epidemiology.