Norovirus is a type of virus that can cause the "stomach flu," among other illnesses. This virus is highly contagious; it can spread easily from person to person through eating food, drinking liquids, or touching surfaces or objects that are contaminated with the virus. Noroviruses are found in the stool or vomit of infected people. An infected person is usually contagious from the moment they begin feeling ill to at least three days after recovery.
(For more information on this topic, including other names that have been used for these viruses in the past, click Norovirus.)