Four outbreaks of norovirus gastroenteritis after consuming
raspberries, Sweden, June-August 2006
So far in 2006, in Sweden, there have been four outbreaks
of norovirus gastroenteritis where raspberries were the suspected vehicle
of infection. The first outbreak occurred at the end of June, the second was
at the beginning of August and the third and fourth at the end of August.
All the outbreaks occurred in the south western part of the country. In total,
43 people became ill and all these people had eaten raspberries as part of
various different dishes.
On 23 June, a group of 15 people met at a private party, where
they ate homemade cake containing cream and raspberries. One or two days
after, 12 people fell ill with gastrointestinal symptoms. Stool samples
from two patients were tested and found positive for norovirus by PCR.
On 2 August, there was a family gathering of 11 people on the west coast
of Sweden. Cheesecake with raspberries was served at the party and was eaten
by all of the guests. The following day, 10 people fell ill with signs and
symptoms typical of norovirus infection. Later, two secondary cases were
reported. No faecal samples were taken, as the patients had already recovered
by the time the outbreak was notified to the authorities. During the outbreak
investigation it was determined that the raspberries in the cheesecake were
of the same brand as in the first outbreak and imported from China.
On 24 August a school class with about 30 pupils aged 13 prepared drinks
with raspberries. A mother of one of the children reported that her child
had become ill on 26 or 27 August. The county medical officer carried out
a cohort study and it was discovered that 12 children had been ill. The
incubation period was 24-36 hours, the symptoms vomiting, fever, diarrhoea
and headache. The duration of disease was 1-3 days. Faecal samples from
two children tested positive for norovirus by PCR. Leftovers of raspberries
in a plastic bag were saved for later analysis. These raspberries were the
same brand as the other outbreaks.
On 25 August, a meeting took place with nine participants. The guests ate
baguettes with filling from a catering company and a homemade raspberry
parfait for dessert. Following this meeting, all nine people fell ill. One
stool sample was taken for testing, and this was positive for norovirus.
Raspberries were left over and saved for testing – results are pending.
These berries were also the same brand as in the previous outbreaks.
All of the suspected raspberries in these outbreaks were the same brand,
and from the same distributor in Sweden who imported these from China. Raspberries
were left over in two outbreaks and results of further tests on the raspberries
are pending. On 23 August two batches of raspberries, were withdrawn from
Outbreaks of gastroenteritis caused by norovirus from frozen imported raspberries
have been reported from several European countries in recent years [1,2,3].
Since 2000 in Sweden, there have been 11 outbreaks of gastroenteritis caused
by norovirus where the suspected food has contained raspberries (database