Which is the most common etiologic agent of acute infantile gastroenteritis?

Though none of the text books specifically mention most common causes of acute infantile gastroenteritis, most of the literature search in pubmed, cochrane and medscape and major text books of pediatrics point to: Viruses are more common causes of gastroenteritits in children. Of the viruses most common is rotavirus. Other viruses implicated are calciviruses, Norwalk, adenovirus. Also E.coli is a major cause of diarrhea in children. Other bacteria are: Campylobacterium, Yersinia enterocolitica, A. hydrophillia.