It is the peak of norovirus season and Pima County, like the rest of the nation, is experiencing an increase in cases.
There have been 145 probable or confirmed cases of norovirus so far in 2025, according to the Pima County Health Department.
In 2024, there were 448 recorded norovirus cases.
Realistically, many more people in the county have been infected, but since the illness has a low incubation period, most people do not go to the doctor.
“If someone got sick for a day or two and didn’t get tested, we have no way of knowing,” said Dr. Lindsay Kohler, Manager of the Epidemiology Division of Pima County Health Department.
What is norovirus?
Contrary to its nickname, “stomach flu,” Norovirus is not the flu. It is a highly contagious virus that causes acute gastroenteritis, or stomach and intestine inflammation.
Symptoms include nausea, stomach pain, vomiting, body aches, fever, and diarrhea. This can lead to dehydration, sleepiness and dizziness.
Norovirus can infect anyone, but genes and age can influence the chances of catching it and symptoms. The young, elderly and immunocompromised may be more at risk.
Dr. Josh Lee, chief information officer and a staff physician at Tucson Medical Center, said his norovirus patients often reported “a sudden onset of very severe vomiting and diarrhea.”
While examining patients, he tries to avoid infection by washing his hands consistently.
“We use the combination of alcohol gels and old-fashioned hand washing, the biggest prevention is handwashing,” Lee said.
Although most norovirus patients start to feel better in one to three days, they can be contagious for weeks, and the bacteria can remain on surfaces for months.
How to prevent the spread
“When people are feeling better, the virus can still be shedding in their stool for two weeks or more after they feel better,” Kohler said.
The CDC reports that someone infected with norovirus can shed billions of microscopic particles while they are sick.
Even a couple of these particles can infect the next person.
Raw shellfish may carry norovirus, but the most common way to be infected is through other people. It can be spread through food, water, saliva and surfaces.
Kohler said parents should be extra cautious when helping children with norovirus, as particles from vomiting can infect them too.
To prevent the spread, it is important to wash hands with soap and water for at least 20 seconds and to avoid handling food for others.
“Hand sanitizer does not kill norovirus,” Kohler said. “Typical household cleaners do not kill it either.”
All surfaces should be cleaned regularly, but the EPA has recommendations for chemicals and products effective against norovirus on its website, most with quaternary ammonium as the active ingredient.
Norovirus season usually lasts until about April, and both Kohler and Lee said the best thing Pima County residents can do to protect themselves is to be aware of the contagiousness and to wash hands regularly.
“Isolate, handwash, don’t touch food and stay hydrated,” Lee said. “If you can do just those four things, you’re going to be in good shape.”
