EAEC clinical disease in weaned pigs and calves is best described as which type of diarrhea?

• A. Bloody diarrhea
• B. Watery diarrhea not bloody
• C. Severe dehydration with systemic signs
• D. No diarrhea

Answer: (B)

Enteroaggregative E. coli (EAEC) causes a secretory-type diarrhea due to its mode of interaction with the intestinal lining and toxin production. It adheres in a characteristic aggregative (stacked-brick) pattern and forms biofilms that stimulate secretion and mucus production, leading to a persistent, watery stool rather than a bloody one. In weaned pigs and calves, this results in watery diarrhea that is not bloody, even though dehydration can occur with ongoing loss of fluid. Bloody diarrhea would point more toward invasive or hemorrhagic pathogens, not the typical presentation of EAEC.