Overview
Noroviruses, including Norwalk, Snow Mountain, and Hawaii viruses, cause an illness in humans called gastroenteritis. Gastroenteritis is an inflammation of the stomach and intestines. Sometimes misnamed "stomach flu," gastroenteritis is not related to flu (influenza), a respiratory illness caused by influenza virus.
Noroviruses are very contagious. They usually are found in contaminated food or drinks, but they also can live on surfaces or be spread through contact with an infected person. Each year in the United States, 23 million norovirus infections result in an estimated 50 thousand hospitalizations and 310 deaths, according to the Centers for Disease Control and Prevention (CDC).