I love the frozen berries. Almost every night I put some in a bowl with oatmeal and milk or yoghurt, and by morning it’s all thawed and yummy and just really fabulous for my colon.

But there’s been this on-going outbreak in European countries that raises the risk specter.

Gillesberg et al. report in Eurosurveillance this week that a foodborne outbreak of hepatitis A in Denmark was notified to other countries on 1 March 2013. A case–control study identified frozen berries eaten in smoothies as potential vehicle. In the following weeks, Finland, Norway and Sweden also identified an increased number of hepatitis A patients without travel history. Most cases reported having eaten frozen berries at the time of exposure. By 17 April, 71 cases were notified in the four countries. No specific type of berry, brand or origin of berries has yet been identified.

In February 2013, Denmark registered a higher than usual number of notified patients with hepatitis A virus (HAV) infection who had no travel history 2–6 weeks before symptom onset or other known risk factors for HAV infection. Concurrently, viruses from six hepatitis A patients who had been notified since October 2012 were shown to be genotype IB with the same sequence across 1,231 nucleotides of the capsid protein VP1 gene, including the VP3/VP1 and VP1/2A junctions (GenBank accession number KC876797). An outbreak investigation was initiated and an urgent enquiry was posted through the European Epidemic Intelligence Information System for food- and waterborne diseases (EPIS-FWD) on 1 March 2013, asking if any other countries had also seen an increase in the number of domestic patients with HAV infection. The sequence was also shared within the International HAV laboratory network managed in the Netherlands.

Following the urgent enquiry, Finland, Norway and Sweden also reported an increase in the number of patients with HAV infection who had no history of foreign travel. Each country identified one or more cases with HAV genotype 1B that had identical sequences to the HAV of the Danish cases. The outbreak is still ongoing. 

The following outbreak case definition was defined in Denmark and applied in all four countries, except that Sweden only includes cases from 1 December 2012 onwards and Finland is not excluding cases with other potential risk factors.

A probable case is defined as a person living in Denmark, Finland, Norway or Sweden with clinical illness compatible with HAV infection and positive for HAV IgM antibodies, no travel history outside of Nordic countries two to six weeks before onset of symptoms or having other known HAV risk factors, such as intravenous drug use, homelessness or male-to-male sexual contact and symptom onset on 1 October 2012 or later.

The full report is available at:

http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=20467