What is the most likely cause of diarrhea leading to mild dehydration in an infant?

• A. Viral gastroenteritis
• B. Bacterial infection
• C. Food allergy
• D. Parasitic infection

Answer: (A)

Viral gastroenteritis is the most common reason an infant develops diarrhea with mild dehydration. Viruses such as rotavirus or norovirus cause a rapid onset of watery stools (often with some vomiting) and a self-limited course. The intestinal lining becomes temporarily unable to absorb fluids efficiently, leading to stool losses, but dehydration remains mild in many cases because the illness is brief and oral rehydration usually restores fluids quickly.

Bacterial infections often bring higher fever, more abdominal pain, and sometimes bloody or bloody-mrocity stools, and can cause more pronounced illness. Food allergies tend to produce signs like fussiness, feeding intolerance, and occasional blood in stool rather than a primarily watery diarrhea with mild dehydration. Parasitic infections typically have a longer duration and different stool characteristics or exposure patterns.