Stomach flu spreads via the “fecal-oral route,” which is just as gross as it sounds. Basically, viruses from infected feces or vomit find their way into our mouths. Very diligent hand washing is your best defense, according to Dr. Rogg.
Wash carefully if you’re changing diapers or cleaning up after a sick child, and grown-ups in the household should clean up after themselves if they can, advises Ryan Madanick, MD, a gastroenterologist and assistant professor of medicine at the University of North Carolina School of Medicine in Chapel Hill, N.C.
You can get it from food
Viral gasteroenteritis isn’t exactly the same thing as food poisoning, which refers to any illness caused by food contaminants, including dangerous toxin-producing bacteria like salmonella. But norovirus is the number-one cause of foodborne illness in the U.S.
Viral gastroenteritis can be spread from person to person or by touching a contaminated surface, but you can also get viral gastroenteritis from sewage-contaminated food or water, or meals prepared or handled by an infected person. (Hence all those “wash your hands” signs in restaurant bathrooms.)