Norovirus, informally dubbed the “winter vomiting disease,” is making its rounds this winter. Weekly test positivity rates have so far surged by 340% during the 2024–25 season, according to a Fortune analysis of Centers for Disease Control and Prevention (CDC) data recorded as three-week moving averages.

Norovirus, the highly contagious stomach bug that causes vomiting and diarrhea, is spiking across the US. What to know about symptoms and prevention.

A surge of norovirus cases, a contagious virus that is the leading cause of foodborne illness in the United States, has medical professionals advising caution. “It is a common cause of illness outbreaks on cruise ships,

Last year, there were 16 outbreaks on cruise ships, from norovirus, salmonella, E. coli or other unidentified pathogens that cause gastrointestinal symptoms such as diarrhea or vomiting. That's the largest number of cruise ship outbreaks in 12 years.

Most norovirus outbreaks occur when people who are already infected spread the virus to others by direct means, such as through sharing food or eating utensils.

Cases of norovirus, a highly contagious stomach bug, are surging in parts of the United States this winter, according to government data.

The FDA has issued an urgent recall for shellstock oysters harvested last month in Washington state's Hammersley Inlet.

Cases of gastrointestinal illness, with norovirus as a likely culprit, are rising in Lancaster County and across much of the nation.

The dreaded norovirus illness known for severe bouts of vomiting, diarrhea and cramps is making life miserable for an increasing number of people as the illness surges.

“The FDA is awaiting further information on the distribution of these oysters and will continue to monitor the investigation and provide assistance to state authorities as needed,” the agency said. The FDA says it will also update the safety alert if more information becomes available.

The number of norovirus cases is increasing across the US, but there are ways to reduce your chances of infection and stave off dehydration and other symptoms.