The Food Safety Authority of Ireland is advising people to boil imported frozen berries following an outbreak of the Hepatitis A virus.
Ten cases of the virus have been identified and half of these have been linked to the consumption of imported frozen berries.
Speaking on RTÉ's News At One, FSAI Chief Executive Professor Alan Reilly warned that Hepatitis A can be fatal in the most extreme cases.
It is of particular concern for the elderly or those with any immune deficiency.
The outbreak has raised concern about all frozen berries, he said.
Prof Reilly said: "The source of this outbreak is not known yet, but all indications are pointing towards imported frozen berries, such as blueberries, raspberries, redcurrants, blackberries and strawberries."
The FSAI is urging people to boil all such berries for at least one minute before eating them, as a precautionary measure.
Italy, Denmark, Sweden, Norway and Finland are dealing with similar outbreaks.
Hepatitis A is a disease that can be relatively mild lasting one to two weeks or more severe lasting months.
The most common symptoms are fever, loss of appetite, nausea, fatigue and abdominal pain, followed by jaundice.
People with concerns can call the authority’s advice line on 1890-336677.