• Gastroenteritis is a very common condition that causes diarrhoea and vomiting. It's usually caused by a bacterial or viral tummy bug. It affects people of all ages, but is particularly common in young children. Most cases in children are caused by a virus called rotavirus. An intestinal infection marked by diarrhoea, cramps, nausea, vomiting and fever. Stomach flu is typically spread by contact with an infected person or through contaminated food or water. Diarrhoea, cramps, nausea, vomiting and low-grade fever are common symptoms. Avoiding contaminated food and water and washing hands can often help prevent infection. Rest and rehydration are the mainstays of treatment.