Disease is usually self-limited
Admit those with systemic symptoms, severe dehydration, inability to tolerate PO fluids, or those with significant co-morbidities
Supplementation with zinc and probiotics reduce severity/duration of diarrhea
Giardia lamblia
Viral 
Helicobacter pylori
Bacterial
Balantidium coli
Campylobacter
Clostridium difficile
Shigella