Four years ago, frozen strawberries imported to Finland from Poland were found to be spreading norovirus across borders.  More than 1,000 Finlanders became sick.  A new norovirus outbreak may be underway, only this time Polish frozen raspberries are the suspected source.

Going into this weekend, the Finnish Food Safety Authority, Evira, warned the population to thoroughly heat all foreign frozen raspberries.

New norovirus epidemics have occurred again in southern Finland since the beginning of October.  A viral analysis of the raspberries is underway and the suspected lot has been withdrawn from the market.  Previous norovirus epidemics occurred in different parts of Finland in May-June, and analyses confirmed Polish frozen raspberries to be the cause. Raspberries had been used in desserts and cakes without first being heated.

Evira urges mass caterers, restaurants, catering firms and consumers to check the origin of frozen raspberries and to only use foreign raspberries after adequate heating in order to avoid food poisoning.

Frozen raspberries of foreign origin should be heated for at least two minutes at 90 degrees Centigrade, according to Evira.

In Finland, the country of origin must be indicated on the labeling of foods if the omission to do so could mislead the consumer.  In light of the current outbreak, country of origin should particularly be checked for foreign raspberries packed in Finland.

Viruses can gain access to berries through contaminated irrigation water. The freezing process keeps the viruses alive and contagious. If the berries are used frozen or are only slightly heated after defrosting, the norovirus is not destroyed. 

Heating is also recommended for other frozen berries of foreign origin, if they are served to persons in at-risk groups, such as elderly people, children, or persons who are immune-compromised.

Norovirus causes stomach upset with nausea, vomiting and diarrhea. Fever and various head and muscle pains are also possible symptoms of norovirus infection.  The symptoms can be very sudden and severe, but usually pass quite quickly (1-2 days).  The virus is highly contagious through contact and aerosols, and affected persons can spread the disease further.  The virus is excreted in feces for several weeks after the diarrhea symptoms have passed, which makes stringent hand hygiene necessary to prevent the spreading of the virus.

The Finnish Food Safety Authority Evira was organized in 2006.  The agency is responsible for control and inspection of imported produce.  Evira also carries out scientific research and risk assessments.