This week’s national wastewater viral surveillance detected highly unusual activity: calicivirus salovirus (fish) saw an 8-fold increase above baseline at Columbia, MO, Riverside, CA, and Boise, ID, while norovirus genogroup IV was up nearly 7-fold at Boise, ID, Kansas City, MO, and Palo Alto, CA. Both represent a notable shift from normal circulation patterns, especially as these viruses are typically undetectable or present at negligible levels in most communities.
Beyond these sharp increases, major alerts remain for high levels of enteric viruses at several large urban centers. Columbia, MO, Riverside, CA, and Boise, ID each report persistently elevated concentrations of rotavirus A, norovirus genogroup I, sapporo virus, and astrovirus, which continue to circulate at absolute levels far above seasonal norms. The detection of picornavirus ampivirus at both Columbia, MO and Kansas City, MO—urban sites with no agricultural context—remains notable due to its high concentration and typically rare detection. Additionally, multiple animal-associated viruses, such as coronavirus tegacovirus, are present at strikingly high levels in urban sites, warranting ongoing clinical and veterinary monitoring.
While SARS-CoV-2 (coronavirus SARS-CoV-2) continues to be detected at low levels in Kansas City, MO, Palo Alto, CA, and St. Louis, MO, its concentrations appear stable, without significant new increases over previous weeks. Influenza B was detected at low levels in Palo Alto, CA, and RSV-B was observed at Columbia, MO, each corresponding to a single urban site. Neither influenza nor RSV show widespread growth, suggesting continued post-peak containment in most locations.
Several viruses rarely observed in wastewater have emerged this week. Coronavirus avian coronaviruses spiked sharply (over 6-fold) in Kansas City, MO and Monett, MO; while expected at rural/agricultural Monett, this emergence in urban Kansas City is more concerning and should prompt further investigation into possible zoonotic introductions. Calicivirus salovirus detections in non-coastal urban communities are similarly unusual and suggest potential new environmental or foodborne transmission routes that may be relevant for public health risk assessment.
Given these findings, enhanced hygiene practices (especially in schools, group settings, and food handling) and up-to-date vaccination for norovirus, rotavirus, and influenza remain important control measures. Exposure risks for animal- and fish-associated viruses can be minimized through proper water and food preparation, with local public health advisories if unusual clusters of symptomatic illness are identified.
Data from several major sites—including Greater Boston, Chicago, Ottumwa, Milan, Sacramento, and Ontario—are currently delayed by one week. Trends at these locations should be interpreted with caution until more current measurements are available to confirm the regional status of emerging viral threats.