Investigation of an outbreak of diarrheal illness following Þorrablót events

Samples of people and food

Stool samples were obtained from a few individuals who became ill in an attempt to identify the causative agent. Samples were also collected from food items that were served at the Þorrablót events. Samples were collected both from leftovers and unopened, sealed food containers from the manufacturer.

The results of the collected samples suggest that the causative agent could be enteropathogenic E. col and/or Bacillus cereus. Results from the sampling revealed that the pork jelly and the sheep's head jelly from the buffets were contaminated with Bacillus cereus and the pork jelly additionally with E. coli. High total bacterial counts indicate that the food may have been left out for a considerable amount of time without adequate refrigeration, allowing the bacteria to multiply.

Conclusions

The samples from the sheep's head jelly and pork jelly from unopened packaging from manufacturers revealed that the product itself was not contaminated. This suggests that the cold chain of the food was broken. The cold chain refers to the system ensuring proper storage, transportation, and handling of products sensitive to temperature changes. These results suggest inadequate food handling by the catering service.

Many reports mentioned suspicions regarding the potatoes and the white sauce they were served in (Icelandic: uppstúfur) as the possible cause, but no samples could be taken from these items since no leftovers were available. Cross-contamination between food items can occur, and the source of the bacteria is uncertain.

E. coli and Bacillus cereus

Enteropathogenic E. coli (EPEC)was identified from the stool samples of people who became ill. Bacillus cereus can cause food poisoning, either by forming toxins in food and causing food poisoning when ingested or by producing toxins inside the body after the bacteria has been ingested. It is difficult to find B. cereus and its toxins in stool samples. Therefore, it cannot be ascertained what the causative agent was. Norovirus was not detected in the samples. It should be noted that there are many different strains of E. coli, and this is a different strain than the one identified in an outbreak at a daycare center caused by STEC (Shiga toxin-producing E. coli) last year.

Buffets and Food Handling

The working group investigating the outbreak emphasizes the risks associated with buffets. Lack of cleanliness in food handling and improper temperatures, which can allow microorganisms to proliferate in the food are among common causes of foodborne illnesses. Warm food should be kept at least 60°C, and food that is to be served cold should be stored in a refrigerator (0-4°C) until ready for serving. The preparation area must be adequate, good internal control must be in place, and handwashing facilities must be sufficient. Utensils should be replaced regularly, and food items that have been out on the buffet should not be reused. For more detailed guidelines on buffets, see the website of the Icelandic Food and Veterinary Authority (Icelandic).

The Health Inspectorate of South Iceland visited the catering service. A serious violation was noted, as the catering service was without a license. Furthermore, the handwashing facilities in the kitchen were inadequate. The Health Inspectorate reviewed the procedures with the catering service and will follow up to ensure that improvements are made.

Final Report of the Working Group

The working group investigating the outbreak is still working on the investigation. The results will be published in the final report soon.

On behalf of the working group on the investigation of the group infection,

The Chief Epidemiologist