Gastroenteritis is an infection or inflammation of the digestive tract caused by viruses, bacteria, parasites, or chemicals. Common symptoms include loss of appetite, nausea, vomiting, diarrhea, abdominal pain, fever and weakness. Treatment depends on the cause but generally involves staying hydrated with oral rehydration drinks and fluids. With proper treatment and prevention of spreading germs, gastroenteritis usually resolves within a few days without long-term effects.