Summary of Recent Wastewater Viral Activity
During the most recent week with data, enteric viral activity in wastewater showed a mixed pattern compared to long-term and seasonal averages. Notably, Norovirus genogroup I and Astrovirus (other) were detected at substantially higher levels than both their long-term and seasonal averages, as well as the previous four-week average. In contrast, Rotavirus A and several other enteric viruses remained well below historical and seasonal norms. Several pathogens, including Human mastadenovirus A and Picobirnavirus, were detected at modest levels, while others were at or near the assay’s detection limit or not detected at all. The overall pattern suggests localized increases for some viral pathogens, with others remaining at baseline or undetectable levels.
Noroviruses
Norovirus genogroup I was detected at markedly elevated levels in the latest week with data, well above both long-term and seasonal averages, and substantially higher than the previous four-week average. This suggests a recent increase in community shedding. Norovirus genogroup II was present at moderate levels, below its historical and seasonal averages but above the recent four-week trend, indicating a possible uptick. Norovirus genogroup IV was not detected, consistent with both recent and long-term trends. Noroviruses are highly contagious and primarily transmitted via the fecal-oral route, often through contaminated food, water, or surfaces. Symptoms include acute gastroenteritis with vomiting and diarrhea. Norovirus activity typically peaks in cooler months, but off-season surges can occur. There is currently no licensed vaccine for norovirus; prevention relies on hand hygiene and surface disinfection.
Rotaviruses
Rotavirus A was detected at levels well below its long-term and seasonal averages, though slightly higher than the recent four-week trend. Rotavirus B and Rotavirus C were not detected, consistent with recent trends and below historical averages. Rotaviruses are transmitted via the fecal-oral route and cause severe diarrhea, especially in young children. Rotavirus A is the most clinically significant, and effective vaccines are available and recommended for infants. Rotavirus activity in wastewater often peaks in late winter and early spring.
Astroviruses
Astrovirus (other) was detected at substantially elevated levels, well above both long-term and seasonal averages, and higher than the previous four-week average, indicating increased community shedding. Astrovirus MLB and Astrovirus VA were detected at lower levels, both below their historical and seasonal averages, with Astrovirus MLB near the assay’s detection limit, so confidence in this signal is lower. Astroviruses are transmitted via the fecal-oral route and cause mild to moderate gastroenteritis, especially in children. There are no licensed vaccines for astrovirus.
Sapporo Virus
Sapporo virus was detected at moderate levels, slightly below long-term and seasonal averages but consistent with the previous four-week trend. Sapporo virus is a cause of gastroenteritis outbreaks, primarily in children, and is transmitted via the fecal-oral route. There is no vaccine available.
Kobuvirus
Kobuvirus aichi was not detected in the latest week with data, consistent with recent and long-term trends. Kobuvirus is associated with mild gastroenteritis and is transmitted via the fecal-oral route. There is no vaccine.
Adenoviruses (Enteric Types)
Adenovirus F40 and Adenovirus F41 were not detected, consistent with a low trend over the past month and below long-term averages. These enteric adenoviruses can cause gastroenteritis, especially in children. Transmission is fecal-oral, and there is no specific vaccine for enteric adenoviruses.
Other Human Mastadenoviruses
Human mastadenovirus A was detected at modest levels, above its long-term and seasonal averages and higher than the previous four-week average, indicating a possible recent increase. Other mastadenovirus types (B, C, D, F) were not detected or were at levels near the assay’s detection limit, so confidence in these signals is lower. These viruses are transmitted via the fecal-oral route and can cause a range of symptoms, from mild gastroenteritis to more severe illness in immunocompromised individuals.
Picobirnavirus
Picobirnavirus was detected at moderate levels, below historical and seasonal averages but above the recent four-week trend. Picobirnavirus is associated with gastroenteritis, primarily in immunocompromised hosts, and is transmitted via the fecal-oral route.
Hepatitis A
Hepatitis A was not detected in the most recent week with data, despite being present in the previous four weeks. Hepatitis A is transmitted via the fecal-oral route, often through contaminated food or water, and can cause acute liver inflammation. A highly effective vaccine is available and recommended for at-risk populations.
Summary and Implications
Recent wastewater data indicate elevated levels of Norovirus genogroup I and Astrovirus (other), suggesting increased community shedding of these viruses. Rotavirus A and several other enteric viruses remain at or below baseline levels. Community members are encouraged to practice thorough hand hygiene, especially after using the restroom and before preparing food, and to disinfect surfaces regularly. Parents should ensure children are up to date with recommended rotavirus vaccinations. Individuals should avoid preparing food for others if experiencing symptoms of gastroenteritis. Those at higher risk of severe illness, such as young children and immunocompromised individuals, should take extra precautions to avoid exposure to contaminated food and water.