The number of foodborne outbreaks almost tripled in Switzerland in 2021 compared to the year before.

This past year, 37 outbreaks were reported with 540 people sick and 40 hospitalized versus 13 outbreaks in 2020.

Officials at the Federal Food Safety and Veterinary Office said the increase could be random, it could be due to better reporting and data collection or it could show the food safety situation has gotten worse, possibly because of the COVID-19 pandemic and other challenges facing businesses.

The agent was unknown in 17 outbreaks but Salmonella caused seven, norovirus four, Campylobacter three, two were due to Bacillus cereus and one each because of Shiga toxin-producing E. coli, Clostridium perfringens and hepatitis E.

Example outbreaks
Frozen berries contaminated with norovirus affected 125 people. The product was sold in catering establishments, hotels, bakeries and retirement homes. Norovirus was found in a sample of berries taken during the outbreak in a hotel. The frozen berry mix came from Serbia and was purchased by a Swiss supplier from a firm in Germany.

In early July, an increase in cases of Salmonella Ajiobo was reported with the last infection in November. Overall, 21 people were sick from 10 parts of the country. All age groups were affected from 0 to 92 years old while 12 cases were women and nine were men. An investigation was unable to find the source.

From September to November 2021, 19 people fell sick in a Salmonella Bovismorbificans outbreak. People over the age of 70 were more affected with 13 men and six women ill. Suspicions fell on a cheese or meat product but the source remains unknown. Salmonella Enteritidis sickened 28 people, with two hospitalized. Contaminated raw eggs used in a chocolate mousse were to blame.

Switzerland also had 18 cases as part of the multi-country Salmonella Braenderup outbreak traced to melons from Honduras.

Between January and May 2021, the Federal Office of Public Health (FOPH) recorded a rise in hepatitis E virus (HEV) infections. A total of 105 patients were noted, 29 were hospitalized and two died. Cases involved more men than women, and ages ranged from 18 to 87. No source was identified but infections were caused by an HEV subtype which is predominant in pigs in Switzerland.

Campylobacter infected two students after a cooking class at a school. Either chicken nuggets were undercooked or the same cutting board was used for the raw chicken and salad.

Two people fell sick and one was hospitalized after eating a pizza with morel mushrooms. The morel, raw or undercooked, is poisonous. Its toxin, haemolysin, is destroyed by heat as long as the cooking time is sufficient.

Illnesses up after pandemic-related dip
The number of foodborne infections in Switzerland increased in 2021 and almost went back to pre-pandemic levels.

With 6,793 cases confirmed by laboratory diagnosis, compared to 6,196 in 2020, campylobacteriosis was again the most frequently recorded zoonosis in 2021.

Salmonellosis was second with 1,487 cases confirmed compared to 1,260 in 2020. The main types were Salmonella Enteritidis, typhimurium and monophasic typhimurium.

A total of 922 Shiga toxin-producing E. coli (STEC) infections were reported, up from 715 in 2020.

With 25 cases of hemolytic uremic syndrome (HUS) in 2021, the figures increased slightly compared to 18 in the previous year. Eleven children under the age of 5 and nine people over 65 were affected.

Listeria was behind 33 illnesses in 2021, which was down from the year before. Men were more affected than women and the most impacted age group were people over 65 years old.

Officials attributed seven cases to different clusters in 2021 thanks to whole genome sequencing. However, clear infection sources could not be found.

Mycobacterium Bovis was detected in four people aged 50 to 84 in 2021 and was linked to infection in their childhood through the consumption of unpasteurized milk. Six cases of Brucella were recorded in people aged 37 to 81 years old, including four men.

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