The message comes after an outbreak of Hepatitis A in an imported berry mix cake which sickened at least 19 people in Norway.
Berries are increasingly imported into Europe, and Norway has seen an increase of this product over the last five years, said the authors of the report.
“In outbreaks, traceback of these products, especially frozen berries, has proven to be challenging and is illustrated in the current European outbreak in which the origin of the berries has not yet been found.
“This highlights the need to improve traceback systems for berries imported into Europe.”
Imported from Germany
Traceback investigations on the Norwegian incident showed that the berry mix buttermilk cake was imported frozen from Germany and distributed to the country.
Marexim recalled berry slices because Hepatitis A was suspected in the berries used in the cake.
The affected product has a best before date of 27-12-2014, Lot number: 3178079418 and product number: EPD nr 2071272.
The firm said the cake was sold to the food service market but may have been sold in packages to individual customers in a limited number of outlets.
RASFF portal said the origin of the cake involved Germany, Poland and Morocco and was distributed to Czech Republic, Finland, France, Germany, Norway, Romania, Slovakia, Spain, Switzerland and UK.
The Norwegian Food Safety Authority (NFSA) said there is nothing to suggest the frozen berries used in production of the cake came to the country through other channels.
The agency said it no longer suspects infected berries are on the market but added berries should be boiled before eating if possible.
On 7 March, an increase in hepatitis A virus (HAV) infections was identified in Norway.
19 cases of HAV infection with a virus strain identical to an ongoing European outbreak were identified and six probable cases.
“On 21 March, the first available typing results showed that 16 domestic cases out of 21 had an identical outbreak strain (NOR-2014-V1) of genotype IA based on a 466 bp sequence in the VP3-VP1 region of the HAV genome,” said the report.
To confirm the association with the European Hepatitis A outbreak ongoing since January 2013 that was associated with consumption of frozen berries the reference laboratory repeated the sequencing using the region used in the case definition for that outbreak.
Results confirmed that the Norwegian isolates were identical to those in the European outbreak.
Fifteen cases were men and all were adults (age range: 24–71 years; median: 43 years).
The patients lived in 15 different municipalities, mainly in the south-east region of the country and onset of symptoms ranged from 7 November 2013 to 9 April 2014.
Five cases bought bags of frozen berries during the incubation period. Three of them had berries left in the freezer and allowed the NFSA to take samples to test for HAV.
Results from samples from two of the patients were negative. Results from the third patient are pending.
“Ongoing Hepatitis A outbreak in Europe 2013 to 2014: Imported berry mix cake suspected to be the source of infection in Norway"
Authors: B Guzman-Herrador, L Jensvoll, M Einöder-Moreno, H Lange, S Myking, K Nygård, K Stene-Johansen, L Vold