The king of noroviruses in Finland has been named

Norovirus has caused the majority of foodborne outbreaks, but salmonella has been the largest, according to an analysis of several years in Finland.

Between 2020 and 2022, 135 foodborne outbreaks were reported and included in the register maintained by the Finnish Food Administration (Ruokavirasto). In total, 2,543 people became ill, 86 were hospitalized and 15 died.

According to a report published by Ruokavirasto and the Finnish Institute of Health and Welfare (THL), a total of 55 outbreaks were reported in 2022, 46 in 2021, and 34 in 2020.

Norovirus was the most common cause of foodborne outbreaks during the period, with 34. Contaminated oysters were linked to five norovirus outbreaks. Salmonella was responsible for 13 outbreaks with 226 cases, Campylobacter was responsible for 12 with 101 cases, Listeria was responsible for seven with 69 cases, five were caused by Yersinia enterocolitica with 40 cases and three were due to E. coli with 90 cases. The pathogen was unknown in 33 outbreaks.

The most significant Salmonella Typhimurium poisoning occurred in June 2021, when 728 people became ill from salad mix in lunches served in day care centers. More than 100 employees and 620 children fell ill. More than 50 children’s organizations received food from the same central kitchen.

Salmonella caused the largest outbreak in 2022 and was part of an EU-wide incident involving chicken. A total of 97 people fell ill in Finland. The severe outbreak has affected 62 people in 2021. Two people developed hemolytic uremic syndrome (HUS) and two died. Salad products were suspected, but food testing did not reveal the contamination strain.

Two clusters of bacteria, one with 23 cases between 2016 and 2020 and the other with 14 cases over the same time period, have been linked to meat products.

Most foodborne epidemics have been small (fewer than 10 cases). Two cases had more than 100 patients; the rest were medium in size, ranging from 11 to 100 incidents.

Bacillus cereus has caused three epidemics in 2020 and 2022, during which 28 people became ill. One of them involved a contaminated oat drink.

Clostridium perfringens also caused three outbreaks that sickened 62 people. Two ETEC outbreaks affected 39 people. Each outbreak was caused by histamine (nine cases) and cryptosporidium (35 cases).

As a result of the research, it was possible to find out that the most common food products that became the causes of poisoning were vegetables and products. In second place are fish and fish products, including shellfish and mussels.

Quite unusual was the hepatitis A epidemic associated with imported frozen raspberries (5 cases). In 2022, an outbreak of hepatitis E sickened four people. E. coli and cryptosporidium caused illness in an outbreak linked to cheese. Another small outbreak of E. coli was linked to raw milk.

The involvement of an infected kitchen worker in food preparation and poor hand hygiene resulted in 23 outbreaks. In almost all of these cases, the causative agent was norovirus. Use of contaminated ingredients has been linked to 18 outbreaks. In 16 outbreaks, there were inconsistencies and errors in food temperature and storage.

The main places where outbreaks occurred were restaurants, cafes or hotels, with 64 outbreaks, followed by homes, with 16 outbreaks. Sixteen national or multi-location outbreaks have also been reported.

Meanwhile, data from Helsinki shows that there were more reports of suspected food poisoning in 2023 than the year before. However, the number of outbreaks investigated dropped from 18 to 13. A total of 245 people became ill.

The number of alerts for suspected food poisoning increased from 654 in 2022 to 795 in 2023. This trend may be due to an increase in restaurant dining or increased awareness among operators to report incidents. In most cases where food poisoning was suspected, the cause was unclear or the illness was not associated with the outlet.

Of the 13 food poisoning outbreaks, norovirus caused four. Three were associated with an infected kitchen worker, and the other was caused by oysters. Contaminated oysters caused 150 people to become ill after eating at various restaurants. Norovirus has been found in Dutch, French and Irish oysters, and several lots have been withdrawn from the market.