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Norwegian health officials are searching for the source of a Yersinia outbreak that has affected at least nine people.
The Norwegian Institute of Public Health (FHI) also reported a further six suspected cases.
Samples from the 15 patients were taken between May 26 and June 15. They are between 10 and 75 years old, and the median age is 29. Eleven of them are women. Sick people live in Trøndelag, Vestfold, Telemark, Østfold, Innlandet, Rogaland and Vestland.
Patients are infected with Yersinia enterocolitica O3. Analyses of the samples showed that confirmed cases have the same genotype, suggesting they may have contracted the infection from a common source.
FHI has opened an outbreak investigation with help from the Norwegian Food Safety Authority (Mattilsynet) and the Norwegian Veterinary Institute.
Patients are being interviewed to find out what they ate, drank, and were exposed to before they became ill.
In 2025, there were 94 Yersinia infections, compared to 90 in 2024. Among cases with a known place of infection, 51 were infected in Norway and 20 were infected abroad. Thirty people were hospitalized. No outbreaks were recorded.
Symptoms of yersiniosis often develop three to seven days after infection. They include fever, abdominal cramps, watery or bloody diarrhea, headaches, and vomiting. Yersiniosis is typically self-limiting, and symptoms can persist from one to three days up to three weeks.
Joe Whitworth
Prior to reporting for Food Safety News, Whitworth worked for William Reed as editor of Food Quality News before becoming food safety editor for Food Navigator. He was named in the Top 40 Food Safety Professionals Under 40 in 2023.
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