Sweden shares multi-year foodborne illness analysis

Sweden has published an analysis of outbreaks over several years that reveals the largest incident sickened 280 people.

The report published by the Swedish Food Agency (Livsmedelsverket) covers foodborne illnesses in Sweden from 2019 to 2023.

The agency said by analyzing data over time, insights can be gained into the state, trends, and risk factors for foodborne infections. It also helps estimate how many people are affected and which food groups contribute the most, enabling risk reduction.

Outbreaks caused by cryptosporidium, Listeria and lectins appear to be increasing. For cryptosporidium and Listeria, this can be partly explained by improved diagnostics. For Listeria, another contributing factor may be the growing proportion of older people. Changing consumption patterns may also explain some of the increase.

Agent and food often unknown
During the period, 142 of Sweden’s 290 municipalities reported food poisoning to Livsmedelsverket. This includes 1,621 incidents, covering 10,139 illnesses. The agency said COVID-19 pandemic restrictions impacted the number and type of foodborne infections.

In 80 percent of all reports, the microorganism or substance that caused illness could not be identified. Bacteria, bacterial toxins, or histamine were indicated as the cause in 11 percent of reports, while viruses and parasites accounted for 7 percent and 1 percent of notices, respectively.

Among reported illness cases, 45 percent were from outbreaks with an unknown agent. Bacteria and viruses each accounted for about 20 percent of cases, while parasites caused 7 percent of the cases. Nine reports during 2019 to 2023 concerned illnesses involving lectins or marine biotoxins.

A total of 11 outbreaks with more than 100 patients occurred during the period. The largest affected 280 people and was caused by lectins in legumes that had not been cooked for long enough. A norovirus outbreak linked to a bakery affected 200 people and Campylobacter infections spread by contaminated chicken sickened 150 people.

In most cases, the food involved was unknown. Vegetables represented the largest category in terms of reported illnesses, followed by composite meals, seafood, and buffet food. Plant-based food categories accounted for 57 reports and 1,925 illness cases while animal-based foods were behind 200 reports and 1,397 cases.

Outbreaks by pathogen
Caliciviruses (mainly norovirus) caused the highest number of illnesses with 112 reports and 2,308 cases. They were reported throughout the year, but the number rose in winter to spring, peaking in March. Composite meals, seafood (especially oysters), and buffet food were most frequently identified in outbreaks. In most cases, the transmission was caused by infected individuals handling food during preparation. Oysters were contaminated in the production area.

Salmonella was behind 33 reports and 749 illnesses. Incidents involved 15 serotypes of Salmonella. Salmonella Enteritidis was the most common type and caused the second highest number of cases. Salmonella Typhimurium, including monophasic Salmonella Typhimurium, infected the most people.

Campylobacter was responsible for 24 outbreaks with 267 cases, Listeria for 21 with 110 cases, Shiga toxin-producing E. coli (STEC) for 17 with 135 cases, and Bacillus cereus for 14 with 110 cases. Cryptosporidium was identified in 20 reports with 697 cases. Leafy greens, especially kale, were a common source of contamination.

Lectins were identified in eight reports with 357 illnesses. Insufficiently cooked beans caused these outbreaks. There are indications that lectin poisoning has become more prevalent compared to previous years, which may be explained by changing consumption patterns combined with a lack of knowledge about the proper preparation of certain legumes, said Livsmedelsverket.

Five outbreaks were caused by Yersinia, four each by Clostridium perfringens and Hepatitis A virus, and one by Vibrio parahemolyticus.

Deficiencies in temperature control were contributing factors, the most common being too high temperatures during refrigeration. Other frequent factors included contaminated ingredients or poor hand hygiene. The top food contamination setting was restaurants and institutional kitchens, followed by primary production and industry.

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Source: https://www.foodsafetynews.com/2025/05/sweden-shares-multi-year-foodborne-illness-analysis/