Between February 8th and 26th, 2023, around 150 people have reported falling ill after eating oysters in restaurants across Helsinki. The illnesses are related to oysters imported from France and the Netherlands.

Reports of illnesses have been recorded from several different restaurants, prompting inspections and sample collections from affected venues. Importers of the oysters in question have also withdrawn their products from the market.

The examination of food samples is still ongoing, but some patient samples have already been completed. So far, seven individuals have tested positive for norovirus related to this outbreak.

Those who have eaten oysters are being encouraged to contact environmental services to provide information for the ongoing investigation.

A report on the outbreak will be prepared for the Finnish Food Authority and the National Institute for Health and Welfare. All known affected individuals will receive a written account of the situation.

Those who suspect that they have fallen ill due to eating food from a restaurant or store are encouraged to complete an online food poisoning report at https://ilppa.fi.

If a food industry operator receives a report of food poisoning from a customer, they have a legal obligation to report it to their local food control authority immediately. Reports should be made at https://ilppa.fi.

Oysters are considered a high-risk food product

Investigations into oyster-related food poisoning occur annually. Eating raw oysters is always a risk, even though not all oysters are contaminated. Oysters filter-feed in seawater and can accumulate norovirus from human waste. Quick heating may not be enough to destroy the virus, as it requires heating to a temperature of +90 degrees Celsius for two minutes to eliminate it.

Restaurants cannot detect norovirus in oysters, and the virus can quickly spread in households and other social settings.

Environmental services will continue to work with the Helsinki epidemiological unit to investigate this outbreak.