Around 150 people reported getting sick after eating oysters in restaurants all over Helsinki between February 8 and February 26, 2023.  The Oysters were imported from France and the Netherlands. Importers of these oysters have also taken their goods off the market.

The examination of food samples is still ongoing. Seven people have so far tested positive for the norovirus associated with this outbreak.

The National Institute for Health and Welfare and the Finnish Food Authority will receive reports on the outbreak.  A business owner in the food industry is required by law to notify the local food control authority right away after learning about a customer’s report of food poisoning.

There are yearly investigations into food poisoning caused by oysters. Even though not all oysters are contaminated, eating raw oysters always carries a risk. Oysters can acquire norovirus from human waste and filter feed in seawater. The virus needs to be heated for two minutes at a temperature of +90 degrees Celsius in order to be eliminated, so quick heating may not be sufficient to eliminate it.

Oysters cannot be tested for norovirus in restaurants, and households and other social settings can become infected very quickly. In order to investigate this outbreak, environmental services will keep collaborating with the Helsinki epidemiological unit.

Seven people became ill from norovirus after eating Swedish mussels. Three people contracted the norovirus from French oysters, and 15 people have fallen ill from Dutch oysters. Twenty people fell ill in Belgium in February as a result of the norovirus found in French oysters.  Several outbreaks involving raw oysters have been reported by Hong Kong’s authorities, including one earlier this year that at least 16 illnesses were linked to an outbreak of Irish-sourced products.

Norovirus illness:

The incubation period for norovirus illness is 12 to 48 hours. Symptoms include nausea, diarrhea, vomiting, sudden onset of cramping and abdominal pain.  One effective way to combat the virus is to wash your hands with soap and water. Norovirus can spread not only through contaminated surfaces, food, and drinks but also directly from one person to another.