Icelandic officials have revealed that 17 people were affected in a Salmonella outbreak from January to May 2024.
The outbreak control team (OCT) had representatives from the Chief Epidemiologist, local health authorities, Reykjavik Health Authorities, the Icelandic Food and Veterinary Authority (MAST), the Microbiology Department of Landspitali University Hospital, as well as district and regional epidemiologists.
The monophasic Salmonella Typhimurium outbreak was identified at the end of January 2024. Initially, it appeared to be confined to preschool children in Húsavík, but cases were then detected in other regions and among older individuals. Over nearly five months, 17 patients with ages ranging from less than 1 to 78 years old were diagnosed with the same type of Salmonella. Eight cases were females and nine were males. Seven were children aged 1 to 3 from Húsavík.
Chicken meat is a very common food item and all infected individuals had consumed it. Food testing and stool samples from kitchen workers at the preschool were negative for Salmonella.
Poultry link
Salmonella Typhimurium was identified in samples from domestic chickens at slaughter in April. This prompted a company called Matfugli to issue a product recall. Results from whole genome sequencing (WGS) later confirmed that Salmonella Typhimurium strains isolated from infected individuals and the chicken were related as both were sequence type 34.
This led investigators to suspect that chicken meat was the source of infections. They said the outbreak investigation highlighted the importance of WGS in tracing the source of foodborne illnesses.
Salmonella was detected at the chicken slaughtering stage several weeks after the largest peak of infection occurred. Officials said this means it is not clear when or how the meat was contaminated.
Samples taken at the farm of the flock in question tested negative for Salmonella. This farm is owned by Matfugli. Two additional flocks tested positive for Salmonella at slaughter, which is believed to have been due to cross-contamination from the first group.
No related Salmonella Typhimurium strains were identified in other European countries.
Monophasic Salmonella Typhimurium had only been detected on one poultry farm previously in Iceland, which is owned by a different producer. Official inspections were also carried out at this farm, which is now used for egg production. Checks revealed that the producer’s own monitoring of Salmonella was in order and no positives were found in official samples.
E. coli outbreak
The final report of a Shiga toxin-producing E. coli (STEC) outbreak in Iceland has also been submitted.
In October, the Chief Epidemiologist received a report of a confirmed STEC infection in a preschool-aged child treated at Landspítali’s emergency department. Other children from the same preschool also sought medical attention for gastrointestinal symptoms. By Oct. 25, the number of confirmed cases had reached 32.
The outbreak affected 49 individuals, including 45 children attending Mánagarður Preschool in Reykjavík and four people connected to the school. Twelve children were hospitalized at Landspítali’s pediatric ward due to hemolytic uremic syndrome (HUS), with five admitted to the intensive care unit. Two children required dialysis due to kidney failure. All children have been discharged from hospital, but some are still being monitored for related complications.
The investigation identified ground (minced) meat used in a meal served at the preschool as the source of infections. Lunch was being cooked in the kitchen onsite when the infection occurred. Microbiological tests confirmed the presence of E. coli O145:H25 in both the meat and stool samples of affected individuals. Meal preparation practices at the preschool, including handling, cooking, and storage, were found to be inadequate.
It was likely that the ground meat was not fully defrosted when cooking began. Other ingredients were then added. The mince did not boil during cooking, then it was cooled at room temperature for up to 5 to 6 hours. It was refrigerated overnight. The next day, mince was reheated and served for lunch with cooked spaghetti. Some of the meat did not reach the cooking temperature needed to kill E. coli and the bacteria could have multiplied when food was kept at room temperature.
Other food samples were negative for E. coli. It is not clear whether children who do not normally eat meat but fell sick accidentally ate mince, were infected due to cross-contamination or by other children.
The Reykjavík Health Authority inspected practices at the preschool, implemented improved food safety protocols, and provided staff guidance. The facility underwent cleaning and disinfection and resumed operations in early November. To minimize risks, the preschool temporarily decided to purchase meals.
MAST contacted a company called Kjarnafæði about findings of E. coli in ground meat. The batch had not been sold to the public, only to restaurants and canteens, including three kindergartens. The company contacted all buyers on the same day and was told all ground meat had been cooked and consumed, so there was no recall. There was no evidence of illness among other buyers.
The mixed ground meat had beef from Germany and mutton from Iceland. Beef was tested by Kjarnafæði on arrival in Iceland and found to be compliant. Mutton came from a Kjarnafæði slaughterhouse and was from the 2023 slaughter season. No sampling for E. coli was done before it went into the mince.
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