Cause
The main viruses that cause gastroenteritis used to be called "Norwalk-like viruses" because Norwalk is the most well-known virus in this group. Now the viruses are referred to as noroviruses.
Noroviruses are not new, but interest in them is growing as researchers learn how frequently they make people sick. Norovirus infections are implicated in newsworthy descriptions of outbreaks on military and cruise ships and in hotels, restaurants, daycare centers, nursing homes, and hospitals. Decontamination of these places has proved to be challenging.
Noroviruses are not related to bacteria or parasites that also can cause gastrointestinal illnesses.