Winter vomiting is the term that has been used to cover the noroviruses such as the Norwalk virus. Norovirus is a frequent cause of diarrhoea and vomiting in the community and can cause gastro-enteritis. Transmission occurs by vomiting, faecal or oral spread or the consumption of contaminated food. As there is a 15-48 hour incubation period it can be difficult to detect in the early stages before diarrhoea and vomiting actually starts. Typically, the illness can last between 12 to 60 hours. There is also a 48-hour period following the last physical signs of symptoms where someone could still be infectious.