Joint ECDC-EFSA assessment - Outbreak of hepatitis A virus infection in four Nordic countries

Risk assessment

Between 1 October 2012 and 8 April 2013, 16 confirmed cases of hepatitis A virus (HAV) infections with subgenotype IB and identical RNA sequence were reported in four Nordic countries.
As none of the cases have a travel history outside the EU within their period of potential exposure, this represents a multicountry outbreak, with exposure currently taking place in the EU.
Epidemiological investigations in affected countries strongly point towards frozen berries as the vehicle of infection.
ECDC, EFSA and the European Commission, in cooperation with the affected countries, will continue to closely monitor this event and will update this outbreak assessment as soon as new relevant information becomes available.

Executive summary

Between 1 October 2012 and 8 April 2013, 16 confirmed cases of hepatitis A virus (HAV) infections were reported in Denmark, Finland, Norway and Sweden.

As none of the cases have a travel history outside the EU within their period of potential exposure, this represents a multicountry outbreak, with exposure currently taking place in the EU. The descriptive epidemiology indicates foodborne transmission originating from a persistent common source with possible multiple vehicles of infection in the EU that are contaminated with viruses sharing an identical sequence.

Epidemiological investigations in affected countries strongly point towards frozen berries as the vehicle of infection. This hypothesis is being further investigated. Ribonucleic acid (RNA) sequencing, interviews of cases in affected countries, food investigations, and purchase history research should provide additional evidence. According to the available information, it is likely that additional cases will be identified and reported.

ECDC, EFSA and the European Commission, in cooperation with the affected countries, will continue to closely monitor this event and will update this outbreak assessment as soon as new relevant information becomes available.