Which bacterium is associated with gastroenteritis after consuming raw shellfish and has a 4-96 hour incubation period?

• A. Vibrio parahaemolyticus
• B. Bacillus cereus (diarrheal)
• C. Staphylococcus aureus
• D. Campylobacter enteritis

Answer: (A)

Vibrio parahaemolyticus is a classic cause of gastroenteritis linked to raw or undercooked seafood, especially shellfish like oysters. The illness typically shows up within 4 to 96 hours after ingestion, which matches the scenario you’re given. Symptoms usually include watery diarrhea, abdominal cramps, nausea, and sometimes vomiting, and the illness is usually self-limiting.

The other bacteria have different typical sources and timing that don’t fit as well. Bacillus cereus diarrheal illness is associated with cooked foods like fried rice and shows up about 6–24 hours after eating. Staphylococcus aureus food poisoning tends to begin much sooner, around 1–6 hours, from preformed toxins in foods. Campylobacter enteritis is commonly linked to undercooked poultry, unpasteurized dairy, or contaminated water and has a longer incubation, typically 2–5 days.