title: Gastroenteritis
context: Gastroenteritis is usually caused by viruses.[4] However, bacteria, parasites, and fungus can also cause gastroenteritis.[2][4] In children, rotavirus is the most common cause of severe disease.[10] In adults, norovirus and Campylobacter are common causes.[11][12] Eating improperly prepared food, drinking contaminated water, or close contact with a person who is infected can spread the disease.[2] Treatment is generally the same with or without a definitive diagnosis, so testing to confirm is usually not needed.[2]
question: What is the most common cause of gastroenteritis?
answers: In children, rotavirus is the most common cause of severe disease.[10] In adults, norovirus and Campylobacter are common causes