Gastroenteritis, commonly referred to as the "stomach flu, include combination of diarrhea, vomiting, and abdominal pain. Fever, lack of energy, and dehydration may also occur. This typically lasts less than two weeks. Depending on the cause, viral gastroenteritis symptoms may appear within one to three days after you're infected and can range from mild to severe Gastroenteritis can be due to infections by viruses, bacteria, parasites, and fungus. The most common cause is viruses. In children rotavirus is the most common cause of severe disease. .Gastroenteritis basically occurs due to eating improperly prepared foods, drinking contaminated water, or through close contact with an individual who is already infected. Treatment initially consists of self-care measures.