A 3-year-old presents with a 24-hour history of diarrhea. The patient is afebrile and the stool is loose and watery with no blood. Fecal WBC is negative. What is the most likely diagnosis?

• A. Viral Gastroenteritis
• B. Toxic Megacolon
• C. Ulcerative Colitis
• D. Intussusception

Answer: (A)

Focus on how diarrhea presents in kids and what the stool tells you.

This scenario shows an acute, non-bloody, watery diarrhea in a young child with no fever and a negative fecal leukocyte test. That combination points to a non-inflammatory, secretory process rather than an invasive or inflammatory one. Viruses, especially rotavirus or norovirus, are classic causes of this pattern in children. They irritate the gut lining and cause rapid, watery stools without white blood cells in the stool, and fever is often absent or mild.

Toxic megacolon would involve severe systemic illness with marked abdominal distension and toxicity, not just a short episode of watery stools. Ulcerative colitis tends to cause chronic or recurrent bloody diarrhea with abdominal pain. Intussusception presents with episodic abdominal pain, crying, drawing the legs up, vomiting, and often a different stool pattern (sometimes dark or currant jelly stools), not simply watery stool over a day.

So the most likely diagnosis is viral gastroenteritis, explained by a non-inflammatory, secretory diarrhea pattern driven by viral infection, with negative stool leukocytes supporting a non-inflammatory process. Management is supportive: oral rehydration and close monitoring, reserving antibiotics for clearly identified bacterial infections or other indications.