Health Beat: Norovirus on the Rise
What you need to know to stay safe this season.
As winter inches closer, conversations about flu shots and seasonal sniffles dominate health headlines. But another virus is quietly making waves across the Bay Area, and it’s not the flu. Norovirus, often called the “stomach bug” or “winter vomiting disease,” is surging locally and nationally, creating a double challenge for public health during the cooler months.
Norovirus tends to hit young children and infants harder than adults. According to the CDC, children under 5 account for nearly 465,000 emergency department visits and almost 1 million outpatient visits each year due to norovirus, primarily because dehydration can develop quickly in this age group.
Dr. Quynh Nguyen Smith, MD, Assistant Professor Touro University College of Osteopathic Medicine gives insight into what she is currently seeing and experiencing with this rise in norovirus. "I have admitted infants to the hospital with Norovirus. The vomiting and diarrhea can often last for several days, leading to severe dehydration.”
Norovirus thrives in cooler weather and crowded indoor settings, which makes November through March the prime season. This year, the Bay Area is seeing one of the largest spikes in a decade, according to wastewater monitoring programs and public health reports. WastewaterScan, a site that tracks disease traces in wastewater, found higher levels of norovirus at treatment plants in San Francisco, Vallejo, Napa, Novato and Palo Alto. California has reported elevated norovirus activity since late fall, with outbreaks in schools, long-term care facilities, and food service settings.
What is Norovirus?
Norovirus is a highly contagious virus that causes acute gastroenteritis, inflammation of the stomach, and intestines. Symptoms often appear suddenly and can include nausea and vomiting, watery diarrhea, and stomach cramps. In some cases, people also experience fever, headaches, and body aches.
Most people recover within 1–3 days, but dehydration can be dangerous for young children, older adults, and those with weakened immune systems.
“These children then need to have an intravenous catheter placed so they can get nutrition through their veins. They have to limit their oral intake while it takes time for the gastrointestinal tract to heal from the effects of Norovirus,” says Dr. Smith.
Norovirus vs. Flu
Despite its nickname “stomach flu,” norovirus is not related to influenza. The flu is a respiratory illness, while norovirus spreads through contaminated food, water, surfaces, or direct contact. Both viruses peak in winter, but norovirus requires only a few viral particles to cause infection, making it especially hard to contain.
Dr. Smith highlights, “Once the diarrhea and vomiting improves, oral nutrients can be resumed slowly with a trial of clear liquids, prior to advancing to solids. For young children, it is important to demonstrate that they can eat orally again before doctors wean their intravenous fluids. They can only go home once they can tolerate a regular diet. That's why it is so important to wash hands thoroughly and do other safety measures to try to avoid getting the virus in the first place!"
As Dr. Smith reminds us, preventing norovirus starts with the basics. Thorough handwashing and safe food practices can make a big difference in stopping the spread and keeping vulnerable populations out of the hospital.
Prevention Tips
Stopping norovirus starts with simple but critical steps. Wash your hands thoroughly with soap and water as hand sanitizer does not kill norovirus. If you’re sick, stay home and avoid preparing food for at least 48 hours after symptoms stop. When you can prepare foods again, wash and cook food thoroughly like shellfish, fruits, and vegetables. Be diligent about cleaning high-touch surfaces. Disinfect with a bleach-based solution since norovirus can survive on countertops for days. Finally, and equally as important, hydrate if symptoms occur seeking medical care for severe dehydration as this is a medical emergency.
Reflecting on the impact this illness can have on families, Dr. Tami Hendriksz, Campus Provost, CAO and Dean of the College of Osteopathic Medicine notes, “Norovirus can be frightening for families because the symptoms come on so suddenly. I always remind parents that while the illness is intense, most children recover fully with supportive care. Knowing what to watch for can make the experience less overwhelming.”