This week’s wastewater surveillance reveals notable and atypical viral activity at several urban sites, led by substantial relative increases in BK virus and Flavivirus XiangYun virus. An 8.9-fold escalation in BK virus was detected at Riverside, CA and St. Louis, MO, marking a sharp and unusual uptick for a virus that is generally present at very low levels. Likewise, Flavivirus XiangYun virus—rarely seen in municipal systems—rose 3.6 times above its recent baseline at Columbia, MO, Palo Alto, CA, and St. Louis, MO. These substantial changes signal possible shifts in population exposure or environmental conditions and warrant closer ongoing monitoring.
In addition to these relative increases, several sites are experiencing continued elevated readings for key enteric viruses. Notably, Riverside, CA, Kansas City, MO, and Columbia, MO are reporting persistently high concentrations of Rotavirus A, Astrovirus (other), Sapporo virus, and norovirus genogroups I and II. While high levels of these viruses are typical for the season, the magnitude and clustering at major urban centers indicate sustained or increasing community transmission risks. Additionally, Rotavirus C levels remain high at Riverside, CA, Kansas City, MO, and Palo Alto, CA, adding to the overall regional enteric virus burden.
Turning to respiratory viruses, SARS-CoV-2 was detected in several samples (Riverside, CA; Kansas City, MO; St. Louis, MO), but there is no evidence yet of significant increases from baseline, with levels remaining relatively stable compared to recent weeks. Pneumovirus RSV-B was observed only at St. Louis, MO, and there were no detections of influenza A or B this period. The relative stability in these respiratory pathogens is a positive development, though continued vigilance is recommended given seasonal transitions.
This week also brought detections of typically rare viral agents—most notably BK virus and Flavivirus XiangYun virus—across several urban settings. Even when present at modest absolute levels, these rare occurrences are epidemiologically important and may point to changes in local ecology, increased host shedding, or unique introduction events. Similarly, the detection of animal-related coronavirus tegacovirus at high levels in urban centers such as Columbia, MO, Riverside, CA, and Kansas City, MO, is noteworthy as these viruses are less expected outside of agricultural contexts.
Given the observed increases and persistently high viral burdens, communities are encouraged to remain attentive to general hygiene practices (such as frequent handwashing and safe food handling), keep up to date with routine vaccinations (including rotavirus and COVID-19 vaccines), and consult local providers if gastrointestinal or respiratory symptoms occur. Public health agencies should maintain outreach and reinforce preventative strategies, especially in areas with ongoing elevated enteric virus levels.
Finally, several sites exhibited data lag this week, with Milan, MO reporting data that is three weeks behind, and a group of other sites (including Greater Boston, Chicago, and Sacramento) lagging by one week. Local interpretations should consider possible underreporting of recent trends, particularly in areas with delayed updates.