Findings suggestive of gastroenteritis include the following: Copious, watery diarrhea Ingestion of potentially contaminated food (particularly during a known outbreak), untreated surface water, or a known gastrointestinal irritant Recent travel Contact with infected people or certain animals E coliO157: H7-induced diarrhea is notorious for appearing to be a hemorrhagic rather than an infectious process, manifesting as gastrointestinal bleeding with little or no stool.