A person washes their hands in a sink.
When your mother told you to always wash your hands before coming to the dinner table, she was right. (For Spectrum Health Beat)

Washing your hands often and thoroughly is the best way to protect yourself if you’re caught in a norovirus outbreak, researchers say.

Norovirus is a stomach bug that causes vomiting and diarrhea. Outbreaks can crop up anywhere and anytime. However, they often occur in densely populated spots with large common areas—cruise ships, vacation resorts, even Olympic villages.

To figure out how norovirus spreads, Arizona State University researchers analyzed data from a past cruise ship outbreak and used a mathematical model to determine how the virus was transmitted.

The main method of transmission, the investigators found, is person-to-person contact. They then assessed the effectiveness of different ways to halt the spread of the virus, such as hand washing and surface cleaning.

“It only takes a few virus particles to make you sick, so no matter how stringent the cleaning, it is next to impossible to remove all the virus from contaminated surfaces,” the study’s lead author, Sherry Towers, said in a university news release.

“However, since the primary route for infection is hand-to-mouth contact, you can’t be infected if you wash your hands thoroughly before eating or touching your face,” she said.

The best way to protect yourself is to wash your hands for at least 20 seconds with soap and warm water before eating food, after using the restroom or touching potentially contaminated surfaces, Towers said. She’s a professor with the university’s Mathematical, Computational and Modeling Sciences Center.

“When your mother told you to always wash your hands before coming to the dinner table, she was right,” Towers said.

The study was published online in the journal Royal Society Open Science.