Norwegian data shows that the number of outbreaks decreased in 2023

The number of outbreaks and sick people fell in Norway in 2023, but last year the country recorded one of the worst E. coli outbreaks on record.

Twenty-five outbreaks were caused by contaminated food, sickening 518 people. This is less than the 34 outbreaks and 628 cases in 2022. In eight outbreaks with 290 patients, the drug was unknown.

The most common pathogen in foodborne outbreaks in 2023 was norovirus five times. Three were due to Salmonella, and two each to cryptosporidium and enterohemorrhagic E. coli (EHEC).

The norovirus outbreaks sickened 105 people. Salmonella Napoli, Salmonella Kintambo and another serotype affected 14 people. The E. coli incidents sickened 36 people and the cryptosporidium outbreaks affected 23 patients.

One Campylobacter outbreak involved 16 cases and one Bacillus outbreak sickened 15 people. Ten cases were reported in an E. coli outbreak and seven in a Listeria outbreak. Two cases of Clostridium botulinum were linked to eating a Spanish omelette (tortilla de patata) in Spain.

Four outbreaks occurred in restaurants, cafes, pubs and fast food outlets, and three occurred in hotels or other accommodations and corporate workplaces.

Vegetables and herbal products were responsible for four outbreaks with 40 cases. Drinking water caused two outbreaks involving 150 patients. Beef and grain-based products were both linked to two outbreaks.

Examples of outbreaks
A national E. coli O26:H11 outbreak affected 24 people, nine of whom developed hemolytic uremic syndrome (HUS). Norwegian officials said it was one of the largest and most serious E. coli outbreaks the country had ever seen.

The cases were aged between 1 and 55 years, with 15 men and nine women. HUS is a serious complication associated with E. coli infections that causes kidney failure and can lead to brain damage and other lifelong complications.

Nordfjord Kjøtt recalled fresh and frozen burgers sold in Rema 1000 stores. The outbreak strain was found in the company’s frozen hamburgers.

Thanks to interviews with patients, an outbreak of E. coli O157 with 12 cases appeared to be linked to hamburgers or ground (minced) meat. Ten people were hospitalized, but there were no HUS cases.

The Salmonella Kintambo outbreak with five cases was traced to sesame seed products from Syria. Three people ate such products before they became ill. Product tests have shown Salmonella Kintambo and Salmonella Amsterdam in Halva from Syria. Whole-genome sequencing data showed that Salmonella Kintambo from patients and a sesame seed product were similar.

Norway has had thirteen cases of this multi-country outbreak linked to contaminated tahini and halva since 2020. People are infected with Salmonella Havana, Salmonella Mbandaka, Salmonella Orion, Salmonella Kintambo, Salmonella Senftenberg and Salmonella Amsterdam.

In mid-June 2023, one case of Listeria monocytogenes was reported with the same genotype as a previous listeriosis outbreak in 2022 linked to smoked salmon. Seven cases were found between June and July. Six people said they had eaten smoked salmon or smoked trout from one producer before becoming ill.

The outbreak strain was found in two unopened packages of smoked salmon from Troll Salmon, which one patient had at home. It was later also found in product samples taken from the manufacturer. The business is temporarily closed to clean and replace some equipment.

Imported leafy vegetables were suspected of being responsible for a Salmonella Napoli outbreak involving seven patients. Four sick people were hospitalized.

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