Bakery products were linked to the most illnesses in 2020, according to an analysis of food poisonings reported to the Swedish Food Agency (Livsmedelsverket).
Food categories behind illnesses included bakery items with 210 cases, chicken with 155 people sick and foods from the sea at 164 cases. Bakery products such as cakes were a source of infection in outbreaks of norovirus and Shiga toxin-producing E. coli (STEC) with 200 and 10 cases, respectively.
Campylobacter in chicken was behind 155 cases. When the source of infection was food from the sea, norovirus in oysters caused 124 illnesses, followed by Vibrio parahaemolyticus in seagrass with 50 sick and histamine in fish with 34 cases.
A new online form for recording incidents launched in January 2020 to raise the quality of data. Municipal control authorities, the County Administrative Boards, and Public Health Agency of Sweden (Folkhälsomyndigheten) conduct epidemiological investigations of foodborne outbreaks and send results to the Swedish Food Agency.
Causes of outbreak and illness decline
There were 173 reports of suspected or confirmed food poisoning with 1,314 cases of illness. In 160 reports, two or more people were infected from the same source.
Compared to 314 outbreaks with 2,835 cases in 2019, the number of reports and illnesses almost halved in 2020. This reduction might have been because of restrictions and recommendations introduced during the COVID-19 pandemic. For example, there were fewer people using restaurants, better hand hygiene among food handlers, and public events where food might have been served were cancelled.
For most reports, the cause was unknown, however for 44 percent of reported cases, some type of virus was cited. This is due to 23 outbreaks with 571 illnesses. Norovirus caused 22 food poisoning outbreaks with 513 cases, Campylobacter was behind four outbreaks with 158 cases and Vibrio parahaemolyticus was associated with one outbreak of 50 patients.
Histamine caused 10 outbreaks, while STEC, Salmonella, Cryptosporidium and Listeria monocytogenes were responsible for a few incidents.
Food poisoning reports were highest between January to March in 2020, with 63 reports and 634 cases of illness. This is due to several oyster-related outbreaks and because fewer events occurred during the rest of the year because of pandemic-related measures, according to the report.
A previous report on infectious diseases in animals and humans found an overall decline in foodborne infections in Sweden in 2020.
Factors behind contamination
For almost two-thirds of cases reported to the Swedish Food Agency, the source was food contaminated early in the production chain, such as in industrial facilities, from there the food was widely distributed to industry or primary production. To reduce the number of poisonings, it is important to have good systems for food safety in primary production and such facilities, said officials.
The most commonly mentioned contributing factor was incorrect storage with respect to time and temperature. This may refer to inappropriate temperature when keeping food heated, or it not be held at low enough temperatures in cold storage. The next most common issue was a contaminated ingredient.
Reporting information on country of origin of contaminated food is optional. Examples of outbreaks traced to countries outside Europe include nine outbreaks from tuna, one of norovirus from frozen raspberries and one with Vibrio parahaemolyticus from seagrass. A number of norovirus outbreaks were linked to oysters from France and some outbreaks were traced to Swedish products.
Climate change impact
Meanwhile, a new analysis from the Public Health Agency of Sweden shows how health in the country could be affected by climate change.
The risk and vulnerability analysis describes 17 different risks based on the estimated probability between 2021 and 2050, different health consequences and current vulnerability and capacity.
The greatest risks to health, in relation to severity and probability, are heat waves and tick-borne diseases. There is a high probability that climate change may lead to poorer drinking water quality and an increase in water- and foodborne infections, according to the report.
Climate change can increase the risk of foodborne infection through a higher risk of contaminated irrigation water being used on fruits and vegetables in Sweden and also via imported food.
During the hot summer months, infectious agents have more favorable conditions for growth and illnesses are often reported because of inadequate handling of food in warmer weather. For example, more people have picnics and barbecues but food handling, cold storage and hygiene advice is not always followed. This means expected longer and warmer summers could result in more people being sick.
The Swedish Food Agency also recently looked at how climate change could affect microbiological food safety in the future, finding the prevalence of most hazards would probably increase.
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