Health professionals are noting a surge in a norovirus called “winter vomiting disease,” which spreads through contaminated food and water.
New federal monitoring shows the virus gaining traction weeks ahead of its typical seasonal curve. Wastewater data tracked by the Centers for Disease Control and Prevention (CDC) indicates infections are accelerating nationwide, with several regions reporting unusually high activity for early winter. Louisiana, Michigan and Indiana have recorded the steepest rises since October, while California, Alabama, Texas and Florida have each reported clusters of localized outbreaks.
Norovirus remains one of the most common causes of gastrointestinal illness in the U.S., and the CDC estimates roughly 2,500 outbreaks are reported each year. But scientists say this season’s surge is tied to a shift in the dominant circulating strain. A variant known as GII.17 drove about 75 percent of documented outbreaks in 2024, replacing the GII.4 strain that had been the leading cause of infections for more than three decades.
“When new strains emerge, people are exposed to a strain that they have not previously been exposed to, and hence are more likely to get infected,” said Lee-Ann Jaykus, a professor in the department of food, bioprocessing and nutrition sciences at North Carolina State University, in an interview with Newsweek. She noted that “historically, new strains emerge every seven to 10 years, and we were due for one, so this is not surprising.”
Public health officials are urging people to stay alert by washing hands thoroughly, disinfecting shared surfaces and steering clear of anyone showing symptoms to help slow continued spread.
