Health officials in a Finnish city are investigating multiple cases of illness caused by contaminated oysters.
Suspected food poisoning in Helsinki related to eating in different restaurants and since early February. Over the past week, officials have reported at least 20 people affected, but updates in local media suggest around 100 have fallen ill.
Investigators tested food at the restaurant and took patient samples and found norovirus. Some sick people reported eating raw oysters.
Some restaurants have been inspected after the suspected epidemic, and oyster importers have begun to issue withdrawal and recall notices.
Food safety officials in Helsinki are asking people who have eaten oysters and become ill to contact them.
Norovirus is the most common cause of foodborne disease outbreaks in Finland. According to the Finnish Institute of Health and Welfare (THL), oysters have caused 11 norovirus outbreaks between 2017 and 2021, in which more than 110 people became ill.
In October 2022, 5 people became ill in this country after eating French oysters contaminated with norovirus.
Wider issues
Finland is the latest report from shellfish The country where the disease is caused. Fishing areas have been closed and outbreaks have also been reported in France, although it is unclear how many people have fallen ill.
In February 20 people fell ill in Belgium due to norovirus in oysters from France. Another outbreak has been linked to oysters from the Netherlands, but authorities have not reported how many people have been affected.
Two outbreaks in Denmark from late 2022 to early 2023 were caused by shellfish. The first case in which 19 people became ill involved oysters from France but originally from Ireland. The second case, 73 cases, is related to oysters from Norway.
Earlier this year, oysters from Ireland caused at least 16 cases of illness in Hong Kong. Authorities in Italy and Luxembourg have also issued oyster recalls due to norovirus.
The incubation period for illness caused by norovirus is 12 to 48 hours. Symptoms include sudden onset of cramps, abdominal pain and nausea, followed by vomiting. Most people also have diarrhea. They usually last 12 to 72 hours.
Washing hands with soap and water is key to fighting the virus. Affected food industry workers should stay off work for at least two days after symptoms cease to avoid spreading infection. Norovirus can be spread directly from one person to another through contaminated surfaces.
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