Norovirus infection is a pandemic viral gastroenteritis caused by norovirus. Norovirus can infect people at any age, and infections occur sporadically around the world. Symptoms include: When a person is infected with norovirus, after an average incubation period of 24 to 48 hours, symptoms of nausea, vomiting, and diarrhea suddenly appear and last for 48 to 72 hours before recovering quickly. Vomiting is common in children and diarrhea is common in adults. It is often accompanied by general physical symptoms such as headache, fever, chills, and muscle pain. Fever occurs in half of patients. Watery diarrhea occurs 4 to 8 times a day. Norovirus enteritis is a type of infection that does not cause inflammation in the small intestine, so it does not cause bloody or mucous diarrhea.