Norovirus are found in the stool or vomit of infected people. They can also be present on surfaces that have been touched by people with the symptoms who are infected. Critically, outbreaks have occurred more often where relatively large numbers of people are contained in a small area, such as trains, buses, schools, army barracks, restaurants, hospitals, nursing homes, catered events and cruise ships. The illness can be incubated for 24-48 hours and have a duration of between 12-60 hours.