The Pasadena Public Health Department confirmed a Norovirus outbreak at its wildfire evacuation shelter.

Public health officials detected three cases of acute gastrointestinal illness in a cluster of 28 people at the Pasadena Convention Center. The department said the illness commonly spreads in communal living spaces like the evacuation shelter.

Norovirus is a very contagious illness that causes vomiting and diarrhea, according to the Centers for Disease Control and Prevention. It is the leading cause of foodborne illnesses in the US, with roughly 19 to 21 million cases every year.

Most people will feel between within three days. Before then, the virus can make someone feel extremely ill with several instances of vomiting and diarrhea throughout the day. It could cause dehydration, especially in children, older adults and people with other illnesses, according to the PPHD.

The department said it will install more handwashing stashing and implement more frequent restroom cleaning as well as disinfectants strong enough to kill Norovirus.

The Pasadena Convention Center is one of the many buildings converted into evacuation shelters following the wildfires in Los Angeles County, including the nearby Eaton Fire.

The wildfire devasted entire neighborhoods in the Altadena and Pasadena areas, destroying more than 7,00 structures -- cementing it as the second-most destructive wildfire in state history, according to Cal Fire.

Some residents were allowed to return to their homes a week after the fire, however, many areas remain closed.

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