Category Archives: Norovirus

Research- Development of an Extraction Method to Detect Hepatitis A Virus, Hepatitis E Virus, and Noroviruses in Fish Products


Hepatitis E virus capsid structure. HEV infection causes viral hepatitis. Atomic-level structure.


Viruses are a leading cause of foodborne disease worldwide. Hepatitis viruses (hepatitis A (HAV) and hepatitis E (HEV)) and human norovirus are recognized as the main viruses of public health concern in food hygiene. ISO 15216 approved procedures are not validated for detection of HAV and human norovirus in foodstuffs, such as fishes, leading to an inability to ensure the safety of these products. This study aimed to provide a rapid and sensitive method for detecting these targets in fish products. An existing method that includes proteinase K treatment was selected for further validation using artificially contaminated fish products, according to the recent international standard ISO 16140-4. Recovery efficiencies in pure RNA extracts of viruses ranged from 0.2% to 66.2% for HAV, 4.0% to 100.0% for HEV, 2.2% to 100.0% for norovirus GI, and 0.2% to 12.5% for norovirus GII. LOD50 values were between 144 and 8.4 × 104 genome copies/g for HAV and HEV, and 104 and 2.0 × 103 copies/g for norovirus GI and norovirus GII, respectively. LOD95 values were between 3.2 × 103 and 3.6 × 105 genome copies/g for HAV and HEV, and between 8.8 × 103 and 4.4 × 104 genome copies/g for norovirus GI and norovirus GII, respectively. The method developed here was successfully validated in various fish products and can be applied for routine diagnostic needs.

Finland – Around 150 cases of food poisoning caused by oysters in Helsinki – Norovirus

Helsinki Times

Food Borne Illness - Norovirus -CDC Photo

Between February 8th and 26th, 2023, around 150 people have reported falling ill after eating oysters in restaurants across Helsinki. The illnesses are related to oysters imported from France and the Netherlands.

Reports of illnesses have been recorded from several different restaurants, prompting inspections and sample collections from affected venues. Importers of the oysters in question have also withdrawn their products from the market.

The examination of food samples is still ongoing, but some patient samples have already been completed. So far, seven individuals have tested positive for norovirus related to this outbreak.

Those who have eaten oysters are being encouraged to contact environmental services to provide information for the ongoing investigation.

RASFF Alert – Norovirus – French Oysters – Clams


Norovirus in oysters from France in Finland


Presence of norovirus genogroup ii in clam (Chamelea gallina) from Italy in Spain

France Research – Acute gastroenteritis: review of the 2020-2021 and 2021-2022 winter seasons

Sante Publique

Every year, an increase in acute gastroenteritis (AGE) is observed caused mainly by the circulation of noroviruses and rotaviruses. Noroviruses are responsible for AGE in people of all ages, while rotaviruses mainly affect children under 5 years of age. 

During the winter season, Public Health France monitors, with its network of partners , the epidemiological evolution of acute gastroenteritis and publishes weekly national and regional epidemiological bulletins on its website . These data are also made available as open data on Géodes .

Santé publique France is today publishing the winter monitoring report covering the 2020-2021 and 2021-2022 seasons in mainland France and recalls the simple actions to take to limit the risk of contamination.

What are the highlights of the last two seasons?

2020-2021: a season marked by a historically low level of activity

The low level of activity observed from March 2020 (end of the 2019-2020 season), in the context of the COVID-19 pandemic, continued during the 2020-2021 season. In city medicine or in hospital emergency departments, activity remained relatively stable and lower than the years prior to the COVID-19 pandemic in all metropolitan areas. 

A return to activity comparable to pre-COVID seasons during winter 2021-2022

The activity levels recorded throughout the 2021-2022 season were again comparable to those observed during the pre-COVID seasons. In hospital emergencies, activity for acute gastroenteritis remained close to historical maximums, from December 2021 to April 2022. Consultations at SOS Médecins were similar to the data observed before the COVID-19 pandemic.

Finland – People sick in Finland after eating oysters – Norovirus?

Food Safety News

Health officials in a city in Finland are investigating several cases of illness caused by contaminated oysters.

Food poisoning in Helsinki is suspected to be related to eating in different restaurants and at an event since the beginning of February. This past week, officials reported at least 20 people were affected but updates in local media suggest there are around 100 illnesses.

Investigators have tested food from restaurants and taken patient samples and have found norovirus. Some of those sick reported eating oysters.

A few restaurants have already been inspected after suspected epidemics and oyster importers have started to issue withdrawals and recall.

Food safety officials in Helsinki asked people who had eaten oysters and then fallen sick to contact them.

Norovirus is the most commonly identified cause of foodborne outbreaks in Finland. Between 2017 and 2021, oysters caused 11 norovirus outbreaks in which more than 110 people fell ill, according to the Finnish Institute for Health and Welfare (THL).

In October 2022, five people fell sick in the country after eating oysters from France contaminated with norovirus.

Finland – Several cases of food poisoning caused by oysters confirmed in Helsinki

Helsinki Times

french oysters

The Environment Services of the City of Helsinki is investigating a number of suspected cases of food poisoning that are believed to be related to dining at several different restaurants and a pop-up event since the beginning of February. Currently, there are about 20 known cases of illness.

The individuals who have fallen ill all consumed oysters, and environmental services have taken food samples from the restaurants as well as patient samples from the city’s epidemiological action. Norovirus has been found in the samples.

The Food Safety Unit is requesting that anyone who has eaten oysters at Fisken på Disken, Ravintola Natura, Ravintola Gillet, The Cock, Ravintola Meripaviljonki, and the pop-up event at Ravintola Sake bar & Izakaya in February 2023 and has fallen ill after their meal, to contact the food safety unit. Illnesses may also be linked to other restaurants.

Those who have fallen ill are encouraged to contact the food safety unit primarily through an electronic food poisoning form at Contact can also be made by phone on weekdays from 8 am to 4 pm at +358 9 310 31527.

Norovirus is the most common cause of sudden intestinal infections in Finland.

USA – FDA Advises Restaurants, Retailers and Consumers to Avoid Raw Oysters from Baynes Sound, British Columbia, Canada Because They Are Potentially Contaminated with Norovirus



The FDA is advising consumers not to eat, and restaurants and food retailers not to sell, and to dispose of oysters that were harvested between January 16, 2023, and February 17, 2023, from Deep Bay, Baynes Sound subarea 14-8 or subarea 13-16 (landfile #140185) in British Columbia, Canada. Consumers who purchased oysters after January 16, 2023, should check the packaging to see if they were harvested in Baynes Sound subarea 14-8 or subarea 13-16 (landfile #140185). Contaminated shellfish can cause illness if eaten raw, particularly in people with compromised immune systems. Food contaminated with norovirus may look, smell, and taste normal. Consumers of these products who are experiencing symptoms of norovirus illness should contact their healthcare provider, who should report their symptoms to their local Health Department.

RASFF Alert – Norovirus – French Oysters


Norovirus in oysters (Crassostrea gigas) from France in Italy

RASFF Alerts – Norovirus – Oysters from France


Norovirus in oysters from France in Belgium


Norovirus in oysters from France in Denmark


Norovirus in oyster from France in Italy

England – Norovirus cases increase significantly in England

Gov UK

Food Borne Illness - Norovirus -CDC Photo

National surveillance data shows laboratory reports of the virus are 66% higher than the average at this time of year. The biggest increase in laboratory confirmed norovirus has been seen in the group of those aged 65 years and over. While high numbers of cases in this age group is expected at this time of year, these levels haven’t been seen in over a decade.

In response to the increase in cases, UKHSA is reminding the public of the actions that they can take to reduce the spread of norovirus.

Norovirus is highly infectious and is easily spread through contact with someone with the infection or with contaminated surfaces. One of the best ways to prevent the spread of norovirus is by practising good hand hygiene. Most people will make a full recovery within 2 to 3 days but it is important to drink plenty of fluids to prevent dehydration, especially for the very young, elderly or those with weakened immune systems who are more at risk.

The number of outbreaks caused by norovirus have increased in hospitals, schools and care homes, with the majority of outbreaks reported in care home settings.

Dr Lesley Larkin, Surveillance Lead, Gastrointestinal Infections and Food Safety (One Health) Division at UKHSA, said:

Norovirus levels are currently the highest we have seen at this time of year in over a decade. Most reported cases are in the over 65s and we’re also seeing a rise in reported outbreaks, particularly in care home settings.

Please stay at home if you are experiencing norovirus symptoms and do not return to work (particularly if you work with vulnerable people or food) or send sick children to school or nursery until 48 hours after symptoms have cleared. If you have a loved one in a care home or hospital, please avoid visiting until 48 hours after symptoms have cleared.

Regular hand washing is really important to help stop the spread of this bug, but remember, alcohol gels do not kill off norovirus so soap and warm water is best.

NHS Medical Director, Professor Sir Stephen Powis, said:

The number of people in hospitals with norovirus has risen significantly in line with what we are seeing in the community and in care homes – it is a really unpleasant illness to catch, but for the vast majority of people it will usually pass in a couple of days, and self-treating at home is the best way to help yourself and avoid putting others at risk.