Wedding Buffet Vomiting Outbreak in Rawalpindi
A wedding caterer in Rawalpindi serves a buffet to 180 guests. Chicken karahi is cooked at 10:30, then kept in covered aluminium pots in a courtyard at 34°C until service at 18:30. At 17:30 the cook reheats it until steaming but does not check the core temperature. Rice is cooked at 15:00 and held in a hot cabinet at 65°C. Raita is made at 16:00 from yogurt and raw onion and kept beside the buffet without ice. A kitchen worker has a discharging cut on his index finger and wears a loose glove while portioning chicken. By 21:30, 46 guests have vomiting and abdominal cramps; 4 also report diarrhoea. Most recover within 12 hours. Two guests have fever and bloody diarrhoea and are admitted. The caterer asks whether the event should be reported and what to do with remaining food.
1. What is the most likely cause of illness in the majority of guests, and how do the two severe cases affect your interpretation?
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Most likely agent. The majority illness fits Staphylococcus aureus food poisoning: vomiting predominates, onset is 2 to 4 hours after the meal, abdominal cramps occur, there is no fever, and recovery is within about 12 hours. The chicken was cooked at 10:30 and held at 34°C for about 8 hours, which allows rapid multiplication and toxin production if the chicken was recontaminated. The reheat to steaming was not verified with a thermometer; even if it reached a high temperature, staphylococcal toxin is heat-stable, so reheating would not make it safe. The worker with a discharging finger and a loose glove is a plausible source of staphylococci. Bacillus cereus emetic type is a differential because it also causes vomiting 1 to 6 hours after eating, but the rice was held at 65°C, which is outside the danger zone if the cabinet worked. The two guests with fever and bloody diarrhoea do not fit S. aureus intoxication; they suggest an invasive pathogen such as Salmonella and should be investigated separately. Do not force all cases into one diagnosis, and do not assume the buffet was safe because most people recovered.
2. Identify the critical control failures and the immediate corrective actions, including what to do with remaining food and symptomatic staff.
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Critical failures and immediate actions. The failures are: chicken held in the danger zone for 8 hours; reheating not monitored to a validated core temperature; no rapid cooling; raita with raw onion held without temperature control; loose glove and bare-hand contact with ready-to-eat chicken; and no employee health reporting for the finger wound. Immediate actions: stop serving and discard all remaining chicken, rice, raita and buffet items from the event; do not try to reheat and serve them. Notify the local health authority and provide the guest list, menu, timing and staff details. Collect leftover food, vomit and stool specimens for the laboratory, and interview all food handlers about symptoms and wounds. Exclude the worker with the discharging finger until the wound is healed or covered with an impermeable dressing under medical advice. Clean and sanitise the kitchen and equipment. The caterer should not prepare food for other events until the investigation and cleaning are complete. Because the staphylococcal toxin is heat-stable, reheating is not a corrective action; the only safe action for implicated food is discard.
3. What food, clinical and environmental samples and what records should be collected to support the investigation?
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Samples and records. Food samples should include leftover chicken karahi, rice, raita, any raw chicken, and swabs of the preparation table and the worker's glove or wound. Clinical samples should include stool and vomit from affected guests, and stool or nasal swabs from food handlers if advised by the laboratory. Environmental samples should include hand swabs of the implicated worker, food contact surfaces, and water if used. Records should include cooking and reheating logs, hot-holding temperatures, buffet times, staff health records, cleaning records, pest control, supplier invoices for the chicken and yogurt, and the list of guests and staff. The records should establish the time-temperature history and whether the hot cabinet was working. For the two severe cases, ask the laboratory to look for Salmonella and other invasive pathogens. The investigation should also check whether other events by the same caterer used the same chicken or equipment. If the caterer has no HACCP-based plan, require one before resuming.