Luncheon Outbreak with Rice Held at Ambient Temperature
At 16:00 on Saturday, the duty manager receives reports that 14 of 60 guests at a 13:00 luncheon have vomiting and nausea; onset was between 14:30 and 17:00. The menu was chicken pilau, steamed rice, coleslaw and custard. The rice was cooked at 11:00 and kept in a covered 30 L pot in the service area, where the ambient temperature was 30°C, until 14:00. It was then reheated to 65°C for 10 minutes and served. The chicken was cooked to 68°C according to the cook's probe, but no log exists. Leftover rice was cooled in the same pot at room temperature overnight and used in staff lunch the next day. Coleslaw was prepared at 09:00 and held in a bowl on the counter. Two food handlers had mild diarrhoea earlier in the week but reported for work. There is no retained sample.
1. Identify the most likely contamination route and the organism group you would prioritise. Explain using the times and temperatures, and state what evidence you would collect.
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The strongest route is cooked rice held for three hours at 30°C, then reheated only to 65°C. That is consistent with Bacillus cereus, whose emetic toxin can form when cooked rice is left in the danger zone and is heat-stable, so later reheating does not make it safe. The short onset, mainly vomiting, and the rice history fit this better than a solely diarrhoeal pathogen. The leftover rice kept overnight at room temperature and then eaten by staff strengthens the hypothesis.
Other routes cannot be dismissed: chicken cooked to only 68°C, coleslaw held on the counter from 09:00, and two handlers with diarrhoea. I would collect:
- The written menu, service times and any temperature logs.
- Interviews with the cook, service staff and ill handlers, including what they ate and when.
- Retained samples if any exist; if not, the leftover rice, coleslaw and custard.
- Probe calibration records and cleaning records for the 30 L pot.
The conclusion must be phrased as a probable cause, not a confirmed one, because there is no retained sample.
2. Set out corrective actions for the operation and the HACCP controls you would verify at the next service.
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Immediate corrective actions:
- Discard the leftover rice and any ready-to-eat food implicated; do not use it for staff meals.
- Exclude the two symptomatic handlers until 48 hours after symptoms stop, and arrange stool testing if the environmental health officer advises it.
- Deep-clean and sanitise the service area, the 30 L pot and all utensils.
- Stop holding rice in a covered pot at ambient temperature. Cook smaller batches and either hold above 63°C or cool from 63°C to 5°C within 90 minutes in shallow containers.
- Reheat rice to 74°C, not 65°C, and record it.
HACCP controls to verify at the next service:
- Cooking: chicken to 74°C; probe and log.
- Hot holding: above 63°C; check every two hours.
- Cooling: 63°C to 5°C within 90 minutes; use shallow pans and record.
- Cold holding: coleslaw below 5°C, not on the counter.
- Personal hygiene: no handlers with diarrhoea; handwashing station stocked.
- Sampling: retain a sample of each high-risk dish for 48 hours.
3. What would you tell the guests and the environmental health officer? Include what not to claim.
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To guests: give a factual, sympathetic message - that 14 people reported illness after the luncheon, that the operation is investigating with the environmental health officer, that implicated food has been withdrawn, and that anyone with severe symptoms should seek medical advice. Offer a single contact point and take details of what each guest ate.
To the environmental health officer: provide the menu, preparation and service times, temperature records that exist, staff illness information, supplier details and samples. State clearly which records are missing, such as the chicken log and retained samples. Do not speculate publicly about a specific organism before laboratory results.
Do not claim that the food was definitely safe because it was reheated, and do not claim that the operation has been cleared before the investigation concludes. Do not identify individual staff or guests. Avoid admitting liability or attributing blame to a supplier without evidence. Keep a written record of all communications.