What clinical finding differentiates infectious diarrhea from other types of diarrhea?

The presence of white blood cells in the stool is a key clinical finding that helps differentiate infectious diarrhea from other types of diarrhea, such as non-infectious or functional diarrhea. When the gastrointestinal tract is infected, particularly by bacterial pathogens, there is often an inflammatory response that results in the migration of white blood cells to the site of infection. This infiltration is a direct indication of the body's immune response fighting off the infection.

In contrast, many causes of non-infectious diarrhea, such as diarrhea due to irritants from food or medications, do not typically provoke an inflammatory response significant enough to lead to an increase in white blood cells in the stool. Hence, the presence of white blood cells serves as a marker of underlying infection, aiding in the diagnosis and guiding appropriate treatment interventions.

Mucus may be present in both infectious and non-infectious diarrhea and does not serve as a definitive indicator of infection. Constipation is generally not associated with diarrhea at all, and while abdominal pain can occur with various types of diarrhea, it is not exclusive to infectious causes. Therefore, the presence of white blood cells is the most specific and clinically relevant finding in distinguishing infectious diarrhea from other forms.