Denmark recorded an increase in foodborne outbreaks in 2021 but the number of infections remained below the average, likely because of COVID-19 related factors.

Figures came from a report published by the DTU Food Institute, Statens Serum Institut (SSI) and the Danish Veterinary and Food Administration (Fødevarestyrelsen).

The number of foodborne outbreaks rose to 63, compared to 35 in 2020 and 51 in 2019. In 2021, 1,257 people fell ill as part of outbreaks. The biggest affected 85 people and six were part of international incidents.

“2021 was dominated by two large foodborne outbreaks in particular. One outbreak with Salmonella in herbal medicine that made 54 people sick, and one with Enteroinvasive E. coli, where 48 people became ill after eating spring onions. Both outbreaks were due to imported, raw products,” said epidemiologist Luise Müller from SSI.

Norovirus is the most common cause of foodborne events. Outbreaks increased from six in 2020 to 14 in 2021 affecting nearly 500 people.

Outbreak highlights
A large national outbreak of Salmonella Typhimurium with 54 cases from November 2020 to July 2021 was recorded. During the outbreak, 32 patients were hospitalized, and three people died within 30 days of testing positive.

Through a case-control investigation and exchange of information between SSI, the Danish Veterinary and Food Administration and Danish Medicines Agency, psyllium seed husks consumed as herbal medicine were identified as the source of infection. Raw psyllium seeds were imported from India. The producer of the medicine and food supplements implemented heat treatment of raw psyllium seeds to prevent future issues.

Denmark reported 41 cases in a multi-country Salmonella Braenderup outbreak linked to melon from Honduras and 12 cases since 2019 in an outbreak traced to tahini from Syria. Seven patients were recorded in an international outbreak of Salmonella Litchfield and eight in a Salmonella Chester incident but the source was not identified.

Seven Salmonella Enteritidis infections were linked to foreign egg products with patients traveling to France and Spain. Another Salmonella outbreak involving Danish eggs affected 26 people.

In the Enteroinvasive E. coli outbreak, 88 people were ill from November 2021 to February 2022. Twenty-six people were hospitalized, and three died. Sick people had bought different ready-to-eat fresh cabbage salads from supermarkets. Spring onions were the only common ingredient and a trace-back investigation showed they came from Egypt.

Three Listeria outbreaks of unknown sources added five or more new patients during 2021 and reached a total of 10 to 14 patients: One started in October 2020 and the other two had been ongoing since 2014 and 2018. Overall, 62 listeriosis cases were recorded versus 43 in 2020.

Reported infections
Registered cases of Salmonella and Campylobacter remained low due to the Coronavirus pandemic affecting reporting, travel and people’s behavior.

Campylobacter was the most common bacterial foodborne illness, with 3,740 confirmed cases in 2021. This was only two cases fewer than in 2020. Three outbreaks with 19, 28 and 16 cases were related to chicken meat in the past year.

Salmonella resulted in 692 laboratory-confirmed infections, which was slightly higher than the 614 in 2020. Salmonella Typhimurium and Enteritidis caused the most illnesses.

A significant decrease was seen in patients with travel reported less than seven days before onset of disease from 28.1 percent in 2020 to 11 percent in 2021. This was probably influenced by pandemic restrictions, according to the report.

Shiga toxin-producing E. coli (STEC) doubled from 448 cases in 2020 to 927 in 2021. The top types were O146, O103, O157, O63, O26, O91 and O145. Two STEC O103 outbreaks sickened 12 people but the source was not identified. A STEC O157 outbreak with 12 patients and a STEC O26 outbreak with four patients remain unsolved.

Yersinia enterocolitica rose slightly from 413 to 453 in 2021. Two outbreaks affected 15 and eight people but the source is not known.

There were seven outbreaks with an unknown agent. The largest with 82 sick people was linked to mixed food at a hotel. Three Clostridium perfringens outbreaks affected 60 people and three Shigella sonnei epidemics sickened 24 people. Two lectins incidents from fried beans and an elderberry smoothie had eight cases and one Clostridium botulinum outbreak from roe sickened five people.

Monitoring figures show the targets for Campylobacter in chicken have been partially achieved and Salmonella in production animals, food, feed, and the environment is in line with previous years.

‟From 2022 there will be focus on further reducing Campylobacter in chicken in a new action plan made in collaboration between the Danish Veterinary and Food Administration, which DTU advises, and the industry,” said senior special advisor Birgitte Borck Høg from the DTU National Food Institute.

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