Noroviruses are a group of viruses better known as winter vomiting disease. Infection with these viruses affects the stomach, causing gastroenteritis. Noroviruses are found in the stool or vomit of infected people and transmitted person-to-person via the fecal-oral route. Symptoms of norovirus illness include nausea, vomiting, diarrhea, and occasionally a high temperature. Those infected normally recover within one or two days, while remaining infectious for another 48 hours.