Invasive diarrhea, or dysentery, is characterized by?

• A. Watery stools without blood
• B. Visible blood or mucus in stools, often with fever and abdominal pain
• C. No fever
• D. Abdominal cramps only

Answer: (B)

Dysentery reflects an invasive infection of the colon, so the hallmark is visible blood or mucus in the stool, often with fever and abdominal pain. The bleeding and mucus come from inflammation and injury of the colonic mucosa caused by invading pathogens, and the fever signals the body's inflammatory response. This set of findings distinguishes invasive diarrheal illness from simple watery diarrhea, which lacks blood or mucus and may not have fever. Abdominal cramps alone without blood does not indicate invasive disease, and absence of fever with watery stools points away from dysentery and toward noninflammatory causes.