Level 1: Causes of Infant Diarrhea There are many causes of infant diarrhea, which are mainly divided into two types: infectious and non-infectious. Infectious diarrhea is caused by bacteria, viruses, parasites, etc. Common ones include rotavirus, E. coli, etc.; non-infectious diarrhea is caused by allergies, food intolerance, etc. Level 2: How to deal with diarrhea in babies