Cholera-like acute watery diarrhea: Which organism can produce an illness closely resembling cholera in clinical presentation?

Introduction:
Several pathogens cause acute watery diarrhea, but only a subset produces a classic cholera-like secretory illness with profuse rice-water stools. This question evaluates recognition of non-cholera etiologies that mimic cholera clinically.

Given Data / Assumptions:

• Cholera-like illness refers to copious watery stools without blood or significant fever.
• Aeromonas species, especially A. hydrophila, can elaborate enterotoxins producing secretory diarrhea.
• V. vulnificus is mainly associated with wound infections and septicemia after raw oyster exposure.
• V. alginolyticus is commonly linked to ear/wound infections; gastroenteritis is less prominent.

Concept / Approach:
Match each organism to its typical clinical syndromes and toxins. Aeromonas hydrophila is known for cholera-like diarrhea; the others are not typical causes of that specific syndrome.

Step-by-Step Solution:
Step 1: Define the syndrome: secretory diarrhea due to toxin-mediated cAMP/cGMP changes.Step 2: Link Aeromonas hydrophila to enterotoxin production and cholera-like disease.Step 3: Recognize that V. vulnificus primarily causes wound sepsis and fulminant bacteremia, not classic cholera-like diarrhea.Step 4: V. alginolyticus is mainly otitis externa and wound-related; diarrheal illness is uncommon.Step 5: Conclude that Aeromonas hydrophila is the best answer.

Verification / Alternative check:
Clinical reviews categorize Aeromonas diarrheal disease as watery and sometimes cholera-like, particularly in tropical regions and in association with contaminated water or food.

Why Other Options Are Wrong:

• Vibrio vulnificus: predominantly invasive soft-tissue infection and septicemia after seafood; not classically cholera-like diarrhea.
• Vibrio alginolyticus: notable for ear and wound infections; cholera-like illness is not characteristic.
• All of these: overinclusive and misleading given the typical syndromes.
• Campylobacter jejuni: causes inflammatory diarrhea with fever and abdominal cramps, often bloody, unlike cholera.

Common Pitfalls:
Assuming all marine vibrios cause cholera-like disease; conflating watery diarrhea of many causes with the specific cholera phenotype.

Final Answer:
Aeromonas hydrophila.