Norovirus, also known as Norwalk virus, is the most common cause of gastroenteritis. The infection, sometimes referred to as the winter vomiting disease, is characterized by non-bloody diarrhea, vomiting, and stomach pain. Fever or headaches may also occur. Symptoms usually develop 24 hours after being exposed, and recovery typically occurs within one to three days. Complications are uncommon, but may include dehydration, especially in the young, the old, and those with other health problems. - Source: Wikipedia