Denmark and Sweden are the latest countries to report outbreaks of norovirus linked to shellfish from France.
At least 180 people in Denmark are sick since the start of the year and 70 are affected in Sweden, although some of these are thought to have fallen ill after eating Swedish oysters.
In France, 1,033 people have been sickened and 21 needed hospital treatment. Italy and the Netherlands have also reported outbreaks linked to live oysters from France.
Products have been recalled due to a risk of norovirus contamination in Belgium, Luxembourg, Switzerland, Hong Kong and Singapore. A total of 23 shellfish growing zones in seven regions have been closed with more than 400 companies affected, according to the French Ministry of Agriculture and Food.
Investigations continue in the Netherlands
Tjitte Mastenbroek, a press officer at the Netherlands Food and Consumer Product Safety Authority (NVWA), said illnesses in the country have not been definitely linked to oysters.
“There are some sick people in the Netherlands, who may have fallen ill from norovirus through oysters, but that has not yet been determined by analysis. It is therefore not yet established that there is a common source of these patients,” he told Food Safety News.
“However, we are aware of the recently increasing number of reports in a European context and the media coverage. We follow developments closely, and as soon as harmful parties are identified, we will monitor their withdrawal from the market.”
Standard advice of The Netherlands Nutrition Centre (Voedingscentrum) for consumers is: “Raw shellfish and crustaceans such as raw mussels or raw oysters can be infected with norovirus. You cannot see or smell this, but you may experience nausea, vomiting and diarrhea. To avoid this risk, it is better not to eat crustaceans and shellfish raw.”
Situation in Denmark and Sweden
The Danish Veterinary and Food Administration (Fødevarestyrelsen) started seeing reports of illness in the first few days of 2020.
Several outbreaks were reported and at least 180 people have been sick with vomiting and diarrhea after eating oysters from France in late December and on New Year’s Eve, according to Statens Serum Institut.
Affected products are sold at fishmongers, supermarkets and restaurants. The agency has informed importers they must avoid oysters from areas closed by French authorities. It is expected that oysters currently on the market come from open areas where no norovirus or other microbiological contamination has been found.
The Swedish Food Agency (Livsmedelsverket) reported that during December and January an unusually high number of people became ill after eating oysters. Outbreaks have occurred in several municipalities with 70 people contacting medical services and seeking help.
Symptoms have mostly been consistent with those for norovirus and in some cases it has been confirmed by microbiological analysis. Norovirus has also been detected in oysters in Sweden and other countries.
Swedish authorities have tracked where oysters that caused illness in the country came from. In some cases it is Swedish oysters that are suspected to have caused illness.
Symptoms of norovirus appear one to two days after being infected and typically last for two or three days. Norovirus is transmitted by having contaminated food or water or from person to person through contact with the skin, objects or inhaling airborne particles. The virus can live for long periods of time on surfaces such as counters and door knobs.
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