Marriage Feast Kheer: Two Plausible Causes of a Food Poisoning Complaint
A caterer in Hooghly prepares 60 litres of kheer for a marriage feast. Milk is boiled at 6 a.m., rice is added and simmered, and the hot kheer is poured at 8 a.m. into two 30-litre aluminium drums. The lids are put on and the drums stand under a fan in the pandal where the afternoon temperature is about 34 °C. Serving runs from 1 p.m. to 2.30 p.m. Leftover kheer is returned to the same drums and kept for the next morning's breakfast without refrigeration. From 6 p.m., about 35 guests report vomiting and abdominal cramps, with no fever and no diarrhoea; most fell ill two to five hours after eating. The caterer says the milk was boiled properly, so the kheer must be safe. Two food handlers have boils on their hands, the same cloth is used to wipe the serving table and the vessels, and washing water comes from a shallow borewell that has never been tested.
1. Name the two most probable causes and explain how you would distinguish between them using the evidence available.
Read the worked answer
Two probable causes, both consistent with a 2–5 hour incubation and vomiting without fever.
- Bacillus cereus, emetic type. Cooked rice in kheer held at 34 °C for five hours is the classic setting: spores survive boiling, germinate in the warm moist mass, and release cereulide, a heat-stable toxin. Illness comes on in 1–6 hours with vomiting and cramps.
- Staphylococcus aureus from the handlers' boils. Skin lesions shed large numbers of organisms; the cloth used on both table and vessels is a direct cross-contamination route; the toxin is also heat-stable and acts in 2–6 hours with vomiting.
How to distinguish:
- Epidemiology: if several families who took kheer from one drum fell ill and those who ate other items did not, the kheer is the vehicle. Ask whether any guest ate rice from another preparation.
- Microbiology: send the leftover kheer and a swab of the handlers' lesions and of the wiping cloth for total plate count and specific testing; matching phage type or toxin gene between the lesion isolate and the food isolate points to S. aureus.
- Dose pattern: B. cereus emetic illness usually follows a large load built up during slow cooling; S. aureus follows handling.
Given the boils, the shared cloth and the untested water, both routes are live; do not let the caterer blame the milk.
2. The caterer insists that boiling the milk makes the kheer safe. Explain precisely why that defence fails, and state the one temperature-time control that would have prevented both causes.
Read the worked answer
Why boiling does not protect the kheer.
- Boiling kills vegetative bacteria, but Bacillus cereus spores survive 100 °C and germinate later in the warm kheer; the toxin they form is itself heat-stable and is not destroyed even by reboiling.
- Staphylococcus aureus is killed by boiling, but any toxin formed before boiling survives; and here contamination happened after boiling, through the handlers, the cloth and possibly the water, when the drums were open for serving.
- The real problem is what happened during those five hours: from 8 a.m. to 1 p.m. the kheer sat at 34 °C, squarely in the danger zone of 5–60 °C, where bacteria multiply fastest. Boiling at 6 a.m. is irrelevant if the food is then left warm.
The control that would have prevented both: rapid two-stage cooling to below 5 °C within two hours, or holding hot above 60 °C until serving. In a pandal, keeping the drums in an insulated hot box above 60 °C is the practical option; if cooling is needed, decant into shallow trays, place in an ice bath and refrigerate. Discard any kheer held in the danger zone beyond two hours - never carry it over to breakfast.
3. The panchayat asks you, as the local food safety resource person, for a corrective action list and the records the caterer must keep. Draft it in a form a small caterer can follow.
Read the worked answer
Corrective action list
- Remove the two handlers with boils from food contact until the lesions are healed and covered; any cut must be dressed with a waterproof coloured plaster and a glove.
- Stop using one cloth for everything. Colour-code cloths: one for tables, one for vessels; wash, then sanitise in hot water with chlorine, and dry in the sun.
- Get the borewell water tested for coliforms; until then, use municipal or boiled water for washing vessels and for drinking.
- Cook kheer in batches sized to the serving time; hold hot above 60 °C; cool any surplus rapidly and refrigerate below 5 °C.
- Serve with a ladle, not hands; keep the drums covered except while serving.
- Clean and sanitise the drums, ladles and the serving area before and after; wash hands with soap at a handwash station with running water.
- Keep the premises free of flies; cover all food; do not store leftovers for another meal.
Records to keep:
- Daily cooking and holding temperature log with times.
- Handwash and staff health register, including skin infections.
- Cleaning and sanitation schedule with sign-off.
- Water test report, renewed periodically.
- Supplier bills for milk and other raw materials, and a sample retention of each feast preparation for 24 hours.
- Complaint and incident register with the action taken.