A high number of Campylobacter infections and more cases of Salmonella infection linked to foods of non-animal origin have been identified in Sweden during a 10-year period, according to a new study.

The document compiles reported foodborne illness for 2008 to 2018. There were more than 4,000 events of suspected or confirmed disease with 30,964 illnesses.

During the period, 194 of the country’s 290 municipalities reported results from investigated incidents of foodborne illness to the Swedish Food Agency (Livsmedelsverket). The number of reporting municipalities per year has increased since the previous summary covering 2003 to 2007.

In 80 percent of reports, the disease-causing agent was unknown. Bacteria or toxins were identified in 13 percent of the reports, while viruses were implicated in 7 percent of them. only a few concerned parasites, marine biotoxins or mycotoxins. Results will be used as a basis for risk assessment and to form priorities to reduce foodborne illness in the country.

Lack of reporting
The report also found only about one in 100 people report suspected food poisoning to the local food control agency. If more did, authorities would be able to trace the cause easier and prevent more people from getting sick.

It showed reporting has increased, but most cases are still unlikely to be brought to the attention of authorities. If agencies quickly become aware of a patient, they can analyze the suspected food and stool samples from the person who is ill.

“Many people probably do not know that you should notify the food control authority in their municipality when you suspect that you have food poisoning. If more people did, the authorities would be better able to track and stop infection and also put in place measures to prevent food poisoning,” said Jonas Toljander, risk assessor at Livsmedelsverket.

Broiler meat was the food category behind the most reported cases with 53 outbreaks and 5,357 cases and most can be attributed to a national outbreak of campylobacteriosis in 2016 to 2017. Mixed foods, such as pizza, kebabs and sandwiches accounted for almost as many cases. Buffet food also made up 98 reports and 1,397 cases while vegetables were linked to 50 reports and 1,265 cases.

Large norovirus and Campylobacter outbreaks
The majority of reported food poisoning cases were caused by norovirus. Mixed foods were most commonly identified as the source in outbreaks. Spread was largely caused by infected individuals handling food during preparation. Food from an open buffet, oysters from other EU countries, and frozen imported raspberries were also frequent sources of contamination.

The largest norovirus outbreak sickened 681 people and was one of 35 outbreaks to affect more than 100 people. There are signs norovirus spread less in Sweden in 2020 than before, as many people have washed their hands better and more because of the coronavirus pandemic.

Campylobacter was the second top cause of foodborne illness with 83 reports and 5,589 cases. The 2016 and 2017 outbreak from chicken affected 5,150 people. In addition to chicken, other meat products, mixed foods, and items such as unpasteurized milk, were implicated in several reports as sources of infection.

Salmonella caused 99 reports and 1,472 cases. Various vegetables were identified as the source of infection for slightly more cases than meat and dairy products. A total of 24 serotypes were found. Salmonella Typhimurium, including monophasic Typhimurium, was mainly reported and also affected the most people. Salmonella Enteritidis was the second most common serotype.

Histamine was responsible for 126 reports, Bacillus cereus for 38, Shiga toxin-producing E. coli for 36, Listeria for 16, Clostridium perfringens for 15 and Shigella for 13. A total of 11 deaths linked to food poisoning were reported in 2008 to 2018 with six caused by Listeria and one due to STEC.

In 223 reports country of origin of the food vehicle was indicated and in 112 it was from abroad. Of these, 68 were reports on food imported from outside the EU.

Most reported cases are caused by improper handling of food by caterers and restaurants. Lack of hygiene skills is the main contributing factor to food poisoning.

Presence of pathogens in food points to deficiencies in primary production or slaughter. Lack of temperature control can lead to bacterial growth and formation of bacterial toxins in food. Apart from risk-mitigating measures in primary production, steps such as improved hygiene and keeping food at the proper temperature could prevent most food poisonings, according to the report.