An investigator detects an outbreak of food poisoning with incubation period of 2–4 hours after a hotel buffet. The epi-curve shows a single sharp peak. Attack rate analysis by food item shows: Rice (50% ate, AR 10%), Chicken curry (60% ate, AR 45%), Salad (40% ate, AR 12%), Dessert (70% ate, AR 11%). The vehicle MOST likely responsible is:
- A Chicken curry — highest attack rate among consumers ✓
- B Rice — highest proportion consumed
- C Dessert — highest absolute number of consumers
- D Salad — exposure to multiple raw ingredients
Explanation
In food-borne outbreak investigation, the food with the highest attack rate among those who ate it is the most likely vehicle. Chicken curry showed an attack rate of 45% among consumers — far exceeding other food items (10–12%). A short incubation of 2–4 hours is consistent with Staphylococcal enterotoxin food poisoning, for which poorly refrigerated pre-cooked chicken is a classic vehicle. Attack rate tables compare rates in those who ate versus those who did not eat each food item — the highest rate difference and highest attack rate in consumers identifies the vehicle.
Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.