Livsmedelsverket (The National Food Agency, Sweden) said there was a number of different outbreak clusters in early February in which a total of 70 people were suspected to be ill.
Fødevarestyrelsen (The Danish Veterinary and Food Administration) said there had many different notifications, some from restaurants, in which around 60 people has been sickened.
Norovirus typically occurs one to two days after being infected and duration of symptoms is typically one to three days.
Both countries posted notifications via the RASFF portal.
A spokesman from Livsmedelsverket told us there was a link to one wholesaler in Sweden which has received two batches of oysters from a company in France.
“This link was made due to epidemiological evidence but the investigation is ongoing. Local municipalities investigate the outbreak and send the information to us. All affected oysters are off the market,” he told us.
“The company involved bought oysters from controlled waters but unfortunately things can still go wrong. Outbreaks of norovirus from oysters have happened before and authorities do what they can to prevent them.”
Norovirus is the most common foodborne outbreak cause in Sweden with 30 outbreaks which sickened around 600 people in 2014.
A spokeswoman from Fødevarestyrelsen told us that 19 notifications had been investigated from late January to earlier February.
The age range of those affected is from mid 20’s to late 60’s and there is a mixture of men and women.
“The oysters came from a French operator and one Danish wholesaler made a recall on 5 February. There were two lots involved and the product should be off the market and we have not had any reported cases since 4 February,” said the spokeswoman.
“We started the investigation with those ill telling us what they had eaten and based on the symptoms and incubation period we found oysters might be the problem and the traceback investigation showed a clear connection.
“Norovirus is quite common but usually it is person to person contamination and not often food sources. There have been previous outbreaks but normally two to three people are involved. In winter it is more of a problem as they are eaten more regularly than in summer.
“Our advice is to be careful when eating oysters, especially if you are in a risk group so someone elderly or with a poor immune system.”
The Danish authorities used PCR to test lots of oysters that remained on the market and found norovirus GGI and GGII.
Løgismose Mejeri og Fødevarer was the wholesaler involved in the Denmark recall.