Influenza A exhibited a significant increase in wastewater signal at Columbia, MO, measured at 43 RPB and 4.4 times its recent 8-week baseline. This represents the most distinct shift in viral nucleic acid abundance among human pathogens this week. Relative abundance measurements for most other priority respiratory viruses—including SARS-CoV-2 and RSV—were stable or detected at low levels, without notable increases across monitored sites.
High absolute levels of enteric viruses were observed at urban sites including Greater Boston, MA, Chicago, IL, and Columbia, MO. Rotavirus A was especially elevated, with measured values reaching 5683 RPB at Greater Boston, indicating persistent and widespread presence in municipal samples. Signals for Norovirus genogroup I (up to 1595 RPB) and Norovirus genogroup II (up to 1310 RPB), along with Astrovirus (4480 RPB), reflect typical seasonal activity and remain consistent with previous weeks. These viruses are routine constituents of wastewater and their high absolute levels are expected during the summer and early fall months.
Several less commonly reported human viruses, such as Salivirus (up to 1498 RPB) and Sapporo virus (up to 1257 RPB), were measured at notable levels in Columbia, MO, Greater Boston, MA, and Chicago, IL. While not unprecedented, their consistent detection across multiple urban locations warrants continued monitoring. No new appearances of other typically rare human viruses were noted beyond those listed above.
SARS-CoV-2 nucleic acids were detected at four sites this week—including Greater Boston, MA; Boise, ID; and Palo Alto, CA—with signal levels stable and not showing unusual increases relative to recent patterns. Influenza A displays elevated levels only at Columbia, MO, and RSV was not highlighted in the current analytic summary. These findings do not imply clinical cases or transmission, and only reflect changing viral material input to the sewer system.
Multiple animal-host viruses were detected at both rural and urban sites, including Coronavirus pedacovirus (pig) at Ottumwa, IA and Sacramento, CA. These measurements, including a 2.3x increase versus baseline at Ottumwa, are routine and expected results of food waste and agricultural runoff. They carry no human-health implication and are not evidence of infection or exposure in the monitored population.
Routine measures are advised for the public. Vaccination against influenza remains recommended, particularly ahead of the fall season. Good hand hygiene continues to be the best defense against enteric viruses such as norovirus and rotavirus. Several site reports, including Riverside, CA, Houston, TX, Milan, MO, Kansas City, MO, Kauai County, HI, Ontario, CA, and Madison, WI, are delayed by one week, and interpretation of patterns at these locations should be made with caution until data recency improves.