Ongoing multi-strain food-borne hepatitis A outbreak with frozen berries as suspected vehicle: four Nordic countries affected, October 2012 to April 2013.

A food-borne 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.