Chances are you've had one or two run-ins with a stomach bug, formally known as norovirus. According to the Centers for Disease Control and Prevention (CDC), this uncomfortable illness is the leading cause of vomiting and diarrhea, as well as foodborne illness, in the U.S. And at the current moment, cases of the virus are spiking.
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Where are norovirus cases spiking?
Per the CDC's NoroSTAT Data Table, 91 new outbreaks of norovirus were reported during the week of Dec. 5. This was a sharp increase from the 69 new outbreaks reported the week of Nov. 28.
While the table doesn't provide additional information on locations, the CDC notes that the NoroSTAT network includes 14 states, namely Alabama, Colorado, Massachusetts, Michigan, Minnesota, Nebraska, New Mexico, North Carolina, Ohio, Oregon, South Carolina, Tennessee, Virginia, and Wisconsin.
Individual cities and states have released alerts about ongoing outbreaks this month, including the Minnesota Department of Health, which reported over 40 outbreaks of the stomach bug as of Dec. 23. The Chicago Department of Public Health issued a warning about "several small outbreaks" of suspected norovirus cases, per NBC Chicago.
Los Angeles County Department of Health published a statement earlier this month confirming it was "investigating a norovirus outbreak associated with oysters that were served at an event on Dec. 3, 2024."
According to The New York Times, over 80 attendees got sick following the event, which celebrated the release of the Los Angeles Times's annual list of the 101 best restaurants in the city. The U.S. Food and Drug Administration (FDA) also issued an alert on Dec. 18 advising consumers in 14 states and Washington, D.C., not to eat certain oysters that were potentially contaminated with norovirus.
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Cruise ships are a particular hotspot for norovirus.
Norovirus is also a threat on cruise ships, accounting for 90 percent of outbreaks of diarrheal disease onboard these vessels. (However, the CDC notes that cruise ship outbreaks only account for about 1 percent of all outbreaks of the virus.)
This month alone, there have been confirmed norovirus outbreaks on three different cruise ships, per CDC data. Hundreds of people were sickened, with December reporting the highest number of cruise ship outbreaks in the span of one month so far this year, CBS News reported.
The CDC does not require state, local, or territorial health departments to report individual cases of norovirus but recommends that health departments report suspected and confirmed outbreaks through the National Outbreak Reporting Systems (NORS) and CaliciNet (a national norovirus outbreak surveillance network).
What norovirus symptoms should I look out for?
Symptoms of norovirus typically appear about 12 to 48 hours after exposure, with the most common being diarrhea, vomiting, nausea, and stomach pain. The CDC cautions that dehydration could also occur, and in severe cases, this can lead to hospitalization.
Less common symptoms include fever, headache, and body aches.
How can I avoid norovirus?
Stomach bugs are tricky because they spread in different ways—and they're "very contagious," the CDC warns. You can get it from eating contaminated food, as well as from direct contact with someone who is sick or with a contaminated object or surface.
The best way to keep yourself safe is to wash your hands, wash your laundry in hot water, and clean and disinfect any contaminated surfaces. When preparing shellfish, make sure to cook them thoroughly and wash your fruits and vegetables.
If you do get sick, the CDC says you should stay home for 48 hours after your symptoms stop.
