Gastroenteritis is quite a common disorder especially during winters and children and babies are the most at risk. The bout of gastroenteritis can last between 24 hours to 10 days. The agent responsible for gastroenteritis can be a germ or a bacterium but in the vast majority of cases it is, as for the flu, a virus. A virus named Rotavirus is most often responsible for gastro in children under five years. Other viruses that can cause gastroenteritis include adenovirus, enterovirus and others. The younger the child, the greater are the dangers of dehydration, which is one of the symptoms