Norovirus Cases Surge Nationwide: What You Need to Know

Norovirus activity in the U.S. is climbing rapidly, with national wastewater analysis led by WasteWaterSCAN showing a 52% jump in viral concentration this fall and CDC test data indicating nearly double the positivity rate since September.

Often confused with the “flu,” norovirus is actually a highly contagious gastrointestinal virus that spreads aggressively through contaminated food, water, surfaces or close contact with an infected person, including those showing no symptoms.

Medical guidance from the Cleveland Clinic, Mayo Clinic and CDC explains that the virus causes acute gastroenteritis, leading to sudden vomiting, diarrhea, stomach cramps and occasionally fever or body aches.

Symptoms typically start 12–48 hours after exposure and last one to three days, though people can continue shedding the virus in stool for weeks.

Health experts say dehydration is the most serious complication, particularly among young children, older adults and anyone with a weakened immune system.

Because norovirus survives heat, cold and many disinfectants, prevention requires careful hygiene: washing hands with soap and water for at least 20 seconds, cleaning high-touch surfaces with stronger disinfectants and ensuring that anyone who has been sick refrains from preparing or serving food for at least 48 hours after symptoms end.