Tracking Norovirus in Tri-County Detroit, MI, Using Wastewater Testing, Syndromic Data, and Online Publicly Available Sources

Human norovirus (HuNoV), the leading cause of acute gastroenteritis in the U.S., is voluntarily reported to the U.S. Center for Disease Control and Prevention (CDC) when infected individuals do not require hospitalization. Wastewater surveillance can be valuable in monitoring HuNoV trends and complementing under-reported clinical data. In this study, wastewater samples were collected between January and December 2023 from three interceptors in Tri-County Detroit, Michigan. HuNoV genogroup I (GI) and genogroup II (GII) were quantified, and the highest concentrations were observed during the winter season. HuNoV GI and GII and their sum were normalized by water quality parameters and fecal indicators. Pearson correlation and dynamic time warping (DTW) analysis were implemented to compare wastewater viral concentrations, in normalized and non-normalized scenarios, with clinical and online data sets. Using the DTW method, HuNoV concentrations in wastewater normalized by fecal indicators and norovirus-positive PCR detection rates in the Midwest U.S. (NPM), followed by Google Trends for “norovirus”, demonstrated the most similar patterns. This study highlights the importance of using multiple data sets, including wastewater surveillance, to identify disease trends, especially for under-reported diseases.