The outbreak, first reported in May 2013 by Germany, has hit Bulgaria, Denmark, Finland, France, Germany, Italy, Ireland, Norway, the Netherlands, Poland, Sweden and the UK.
It was identified when Germany reported cases with a travel history to Italy, which in turn revealed a national increase in the number of hepatitis A cases.
The most recent case was reported on 4 June in Finland.
Italy reports majority of cases
To date 1,444 cases have been reported in twelve European countries, 331 of which have been confirmed by genotyping. The majority of confirmed cases were reported in Italy (90%).
Hepatitis A contamination of mixed berries and mixed berry containing products was identified in Italy, France and Norway.
Following the European-wide trace-back investigation, Bulgarian blackberries and Polish redcurrants were identified as the most common ingredient in the food consumed by affected people, however, Poland is the largest producer of redcurrants in Europe, and Bulgaria is a major exporter of frozen blackberries.
No single point source of contamination has been identified but twelve food operators have been identified with links to cases and batches in five of the countries affected.
Hepatitis A virus (HAV) cases/lots in five countries could be linked to seven Polish freezing processors and/or to five frozen berry suppliers in Bulgaria, said EFSA.
“This indicates that HAV contamination could be occurring at the freezing processor or in primary production of berries and therefore compliance with Good Hygiene Practice, Good Manufacturing Practice and Good Agricultural Practice is recommended for countries producing berries for freezing.”
The agency said one conclusion is that there was a single point source for the outbreak, but information to confirm this is lacking.
The other is a high-risk practice in the production or freezing of berries or endemic occurrence of HAV OS in the region of production or the subpopulation of seasonal workers resulted in HAV contamination in multiple locations and at multiple time points.
However, uncertainties related to different investigation and sampling strategies; a lack of background information on berry production methods, the fact that only information relating to confirmed/suspect lots was analysed; recall bias on the part of cases; and the possibility of errors in the collation of the tracing data prevent a final conclusion.
The Food Safety Authority of Ireland (FSAI) has advised consumers to continue to boil all imported frozen berries for at least one minute prior to eating.
The agency said some cases of hepatitis A have been reported this month which cannot be explained by travel abroad and investigations are underway to establish if there may be a link with contaminated imported frozen berries or other foods.
Prof. Alan Reilly, chief executive of the FSAI, said it recommends boiling imported frozen berries for at least one minute before eating them.
“This is a precautionary measure and will destroy the virus if it is present. There is no evidence that fresh Irish berries were the cause of the outbreak”, he said.
“However, we suggest that - as with all other fruit and vegetables - fresh berries should be washed thoroughly if they are being eaten uncooked.”
Reilly added that the outbreak highlights just how complex the food chain can be.
“No single point source of contamination has been identified, despite the trace-back investigations which looked at 6,227 transactions among 1,974 food businesses,” he said.
“We reiterate our recommendation that food businesses at each stage of the food chain seek assurances regarding the effectiveness of the food safety management systems in place from their suppliers.”
Read the full EFSA scientific report HERE.