An inflammation of the lining of the stomach and intestines. It is frequently due to infectious agents (e.g. campylobacter and salmonella), but stress and food allergies can be responsible. In some cases CMV or HIV itself may be responsible. Symptoms include diarrhoea, vomiting, headache, nausea and stomach cramps. Treatment depends on the cause but generally includes anti-diarrhoea medication and measures to prevent dehydration and malnutrition.