US Wastewater Surveillance Finds Norovirus Levels High

Norovirus, a highly contagious virus that causes acute gastroenteritis, is circulating at elevated levels across multiple regions of the United States, according to wastewater surveillance data. The virus, known for triggering sudden vomiting, diarrhea, and stomach cramps, is showing sustained transmission nationally, with particular activity noted in the Northeast and Midwest.

Data from the WastewaterSCAN monitoring program indicates norovirus levels remain high nationally, with no clear upward or downward trend over the past 21 days, suggesting ongoing community spread. Amanda Bidwell, the scientific program manager for WastewaterSCAN, stated that national levels are in the high category due to recent concentrations. The Centers for Disease Control and Prevention’s NoroSTAT program recorded 1,194 outbreaks from August 2025 to May 2026 in participating states, a figure consistent with past seasonal averages.

While outbreaks can occur year-round, norovirus typically follows a seasonal pattern, most commonly seen from November through May in the Northern Hemisphere. Experts note the current rise aligns with normal seasonal patterns, not representing an unusual surge. Infectious...