The infections started in May and continued until June, mostly occurring in southern Sweden, prompting the National Food Agency (Livsmedelsverket) and Public Health Agency (Folkhälsomyndigheten) to investigate the matter.

In every case the virus was traced back to frozen strawberries imported from Poland, which were not heated before being consumed, either in the form of smoothies or in desserts.

The fruit was sold by a Polish company to a Swedish wholesaler, who then in turn sold the goods on to restaurants and catering firms. A recall of the strawberries is still ongoing, with the wholesaler asking customers to either throw them away or send back any remaining fruit.

Livsmedelsverket recommends boiling frozen strawberries for at least one minute before consumption, as the heat kills the hepatitis A virus.

Sweden has in the past seen similar cases of infections caused by the consumption of frozen fruit, with one such outbreak of a vomiting bug at an elderly care home in 2015 leading to the death of three pensioners.

READ ALSO: Raspberries confirmed as source of deadly bug at care home

A warning from Livsmedelsverket to boil frozen raspberries for at least a minute is written on their packaging, but the same is not the case for strawberries.