More than 100 people have fallen ill in Norway from norovirus likely in a frozen seaweed salad from China.

The first outbreak of norovirus suspected to be linked to the seaweed salad occurred in mid-June and the most recent was at the beginning of August. The implicated product was also shipped to Denmark.

“It is suspected that seaweed from China was the cause of more than 100 cases of gastroenteritis from at least 11 eateries in different areas of Norway. Most of the outbreaks were in June and July this year. Investigations are still ongoing. Norovirus was detected in patients from at least two of these eateries,” Guri Aanderud, senior adviser in the seafood section at the Norwegian Food Safety Authority (Mattilsynet) told Food Safety News.

“We have no information regarding individual cases such as age, sex, place of residence, or hospitalization related to these outbreaks as norovirus is not notifiable in Norway. However, symptoms of norovirus are generally mild and self-limiting. All involved restaurants have received and served seaweed salad from two different lots in the relevant time period. Many of the people who reported illness have stated that they have eaten dishes containing seaweed salad.”

Product recall

On Aug. 22, Goma Wakame Seaweed salad bags of 1000-gram imported into Norway by Østlandske Formidling AS (Øfas) were withdrawn from the market due to suspected norovirus.

Product was sold to the food service sector in Norway but distribution may have included several stores across the country. It was imported into Denmark by World Seafood and is produced by Dalian Kowa Foods Co. in China.

Affected bags have item number 8032 and lot number 1904, which was manufactured on March 14, 2019, and lasts until March 13, 2021, and lot number 1811, which was made on November 8, 2018 and lasts until Nov. 7, 2020.

Since withdrawing the product, no further outbreaks linked to seaweed salad have been reported.

The Norwegian Food Safety Authority took product samples that have not yet been fully analyzed and the Norwegian Institute of Public Health (FHI) has informed the European Centre for Disease Prevention and Control (ECDC) via the Epidemic Intelligence Information System (EPIS).

Spanish outbreak and further distribution

Aanderud added it also knew of a Spanish RASFF alert from Aug. 13, 2019 related to a foodborne outbreak caused by norovirus GI and GII in frozen seaweed salad from China, via Germany.

Countries part of this notice include Austria, Germany, Greece, Italy, Portugal, Romania, Slovakia, Spain and the United Kingdom.

The International Food Safety Authorities Network (INFOSAN) was mentioned in both RASFF notifications.

Adam Bradshaw, technical officer in the Department of Food Safety and Zoonoses at the World Health Organization, said INFOSAN was working with colleagues at the European Commission’s RASFF because the frozen seaweed salad suspected to be responsible for the outbreak was distributed from China.

He added it does not have the authority to disclose non-public information on behalf of countries involved in the outbreak when asked which countries had reported cases and how many.

“To better understand the potential international aspects of this event, we have been in contact with the INFOSAN emergency contact point in China to seek details as to whether the implicated frozen seaweed salad has been distributed from China to any other countries. once further information is available, we will updat all INFOSAN members through the INFOSAN community website,” said Bradshaw.