First came the fires. Then, there was ash and contaminated water. Now, some survivors of the Southern California wildfires are dealing with outbreaks of norovirus and other stomach ailments at a shelter set up to help evacuees.

"It is too early to tell if this strain is associated with more severe norovirus disease but likely lower population immunity is the reason for the early surge of an otherwise seasonal increase of this virus," Jan Vinjé, head of the CDC's CaliciNet system, told CBS News in an email.

As the norovirus cases continue to spread in the U.S., you can't rely on hand sanitizer alone to protect you, experts warn.Norovirus causes gastrointestinal symptoms like nausea, vomiting, diarrhea and stomach cramps.

Infectious disease doctors explain if hand sanitizer kills norovirus, and effective ways to neutralize the stomach bug’s germs, including on surfaces.

The cases mark the fourth norovirus outbreak on Holland America ships since early December, following others on its Eurodam, Rotterdam and Zuiderdam vessels. Other companies, including Cunard Line and Princess Cruises also saw outbreaks in recent weeks.

Drivers of the increase in norovirus cases may include a new strain, but continued precautions, good hygiene, can help reduce risk.

You can also get norovirus by touching objects or surfaces that are contaminated and then putting your hands in your mouth without washing them first. Hand-washing with soap and water is key, as hand sanitizer will not do the trick in the case of norovirus, experts say.

What’s worse, there’s no real treatment for norovirus beyond getting plenty of rest and constant fluids infused with electrolytes. The virus typically only lasts one to three

Viral sicknesses have risen in early 2025 amid the ongoing “quad-demic” in the U.S., referring to three respiratory viruses and one gastrointestinal disease, according to the Centers for Disease

“We are seeing somewhere in between 10 to 20 patients each day in the Children’s Hospital who need admissions,” Chief Medical Officer for Kentucky Children’s Hospital Dr. Lindsay Ragsdale said. It’s one of many reasons why Kentucky is one of four states ranked high for respiratory illness activity by the CDC.