Salmonella caused the most outbreaks and outbreak-related illnesses but Listeria was behind the most deaths in Europe in 2021, according to a new report.

Salmonella accounted for almost 20 percent of all outbreaks. The top sources of salmonellosis outbreaks were eggs, egg products, and mixed foods, which are meals composed of various ingredients.

Outbreaks caused by Listeria monocytogenes were at the highest level ever but the number of sick people and deaths did not rise. This might be linked to the increased use of whole genome sequencing, which allows scientists to better detect outbreaks, according to the report.

Outbreaks in 2021 went up compared to 2020 but were below pre-COVID-19 pandemic years, said the European Food Safety Authority (EFSA) and European Centre for Disease Prevention and Control (ECDC).

More than 4,000 foodborne outbreaks, 32,543 illnesses, 2,495 hospitalizations, and 31 deaths were recorded in 2021. Also, 83 outbreaks, 1,270 patients, 65 hospitalizations, and two deaths were reported in Bosnia and Herzegovina, Iceland, Montenegro, Norway, North Macedonia, Serbia, and Switzerland.

The largest outbreak was in Finland, and most deaths were in France
Belgium, France, the Netherlands, and Poland accounted for almost 75 percent of all outbreaks. France had 1,286, the Netherlands had 838, Belgium had 547, and Poland had 299.

Finland reported an outbreak caused by Salmonella Typhimurium in pre-cut vegetables involving 728 patients. This outbreak was the largest in 2021 and the biggest caused by this pathogen since data collection began in 2004.

With 17 fatalities, France accounted for more than half of all deaths in the EU. This is the highest from a single country since 2012. At the EU level, 15 deaths were linked to health care and residential facilities, which emphasizes the risks of foodborne hazards to vulnerable people, researchers reported.

The agent was unknown for 1,831 outbreaks, with more than 10,100 patients and three deaths. Salmonella was responsible for the majority of outbreaks, cases, and hospitalizations. Unspecified bacterial toxins were behind 484 outbreaks and norovirus caused 251. Listeria monocytogenes was associated with the most deaths with 12.

France reported 176 Salmonella outbreaks while Poland had 165, Slovakia 154 and Spain 93. Salmonella Enteritidis was the top serovar, followed by Typhimurium. Salmonella was the main cause of outbreaks in 17 EU countries.

Shiga toxin-producing E. coli (STEC) was the third most common bacterial agent with 31 outbreaks and 275 patients. It was the top cause in Ireland. Identified serogroups in 24 outbreaks were O157, O26, O103 and once each for O12, O145, O146 and O91.

Campylobacter was the fourth most reported agent in outbreaks with 249. Germany was top with 64, followed by France and Slovakia both with 55. Six severe outbreaks leading to deaths or hospitalizations were reported by Denmark, France, Spain, and Sweden. The six deaths were the highest number reported since 2007.

Yersinia was detected in 21 outbreaks from 12 countries with 125 patients. Six countries reported 11 outbreaks caused by Shigella with 63 cases. Six were due to Shigella sonnei.

One outbreak was caused by Cronobacter sakazakii in Germany. It involved four newborns and caused one death. The implicated food was a hospital-mixed probiotic formula for infants. This was the first outbreak since EFSA began collecting data in 2004. Vibrio cholera was also reported for the first time with 47 cases. It was detected in Spain, in a residential institution (nursing home, prison or boarding school) and was linked to mixed food.

Contributing factors and food links
France recorded 90 percent of all outbreaks caused by bacterial toxins with more than 600. Three epidemics led to 708 cases and 97 hospitalizations. Seven deaths involved people living in health care and residential facilities. Bacillus cereus was associated with the most outbreaks among bacterial toxins, Clostridium perfringens caused the highest number of cases and deaths, and Staphylococcus aureus was top for hospitalizations.

Norovirus was the leading agent in Belgium, the Czech Republic, Denmark, Finland, Latvia, and Sweden. Thirteen outbreaks involved more than 100 people. France had the most with 112 outbreaks. 

Czech Republic reported a major outbreak of hepatitis A, involving 199 cases, of which 195 needed hospitalization. Mixed food was the suspected vehicle. Hepatitis E in Switzerland affected 105 people with 29 hospitalizations and two deaths. Slovakia reported an outbreak with five cases caused by tick-borne encephalitis virus linked to raw goat’s milk.

Almost 50 outbreaks and more than 200 cases were due to histamine and Scombrotoxin, often caused by fish products. Marine biotoxins such as Ciguatera were behind 17 outbreaks and mushrooms were linked to six. Two lectin outbreaks were reported in Denmark and one atropine incident linked to vegetables was noted in Italy.  

Foods of animal origin were implicated in 202 outbreaks, 2,221 cases, 316 hospitalizations, and 11 deaths. There was an increase in outbreaks linked to vegetables and juice products. Salmonella in this product category caused the most illnesses with more than 1,100.

Salmonella in mixed foods was responsible for the most hospitalizations, followed by Salmonella in egg products and in vegetables and juice products. Listeria in fish products was responsible for the most deaths followed by Clostridium perfringens toxins in pig meat products.

Cross-contamination was reported as a contributing factor in 34 outbreaks. An infected food handler was identified in 26 outbreaks. Time or temperature storage abuse, inadequate heat treatment, and inadequate chilling were also reported.