Surge in Norovirus Cases: Public Urged to Avoid Raw Oysters and Maintain Hygiene

CHP reminds public not to consume raw oysters and observe food safety as norovirus-related food poisoning cases surged recently

In view of the recent surge in norovirus food poisoning cases related to consumption of raw oysters, the Centre for Health Protection (CHP) of the Department of Health today (February 5) urged the public to stay vigilant, maintain personal, food and environmental hygiene at all times, and avoid consuming high-risk foods like raw oystersto prevent foodborne diseases.

Recent surge in norovirus-related food poisoning cases

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"Food poisoning cases have increased significantly in the recent month, rising from one case a week on average in late December last year to four cases a week on average in January. A total of 16 cases have been recorded in the first five days of February. Since January 18, the CHP has so far recorded 23 food poisoning cases, affecting 69 persons. Among which, 20 cases (87 per cent) were related to norovirus, affecting 57 persons. Epidemiological investigation showed that all cases were related to raw oyster consumption. The places of origin of the raw oysters include Korea, France, Ireland, Spain, etc. Among the affected persons, five persons were hospitalised for treatment. All are in stable condition. The CHP has notified the Centre for Food Safety (CFS) of the Food and Environmental Hygiene Department (FEHD) to follow up on the food poisoning cases," the Controller of the CHP, Dr Edwin Tsui, said.

"As oysters feed by filtering a large volume of seawater, pathogens can accumulate in them if they are grown in or harvested from contaminated water. Raw and partially cooked oysters are considered a high-risk food. Persons who consume undercooked or contaminated oysters may contract food-borne diseases such as norovirus, hepatitis A virus or other bacteria. In view of the drastic increase in food poisoning cases related to consumption of raw oysters recently, members of the public, especially pregnant women, young children, the elderly and people with weakened immune systems or liver diseases, shall stay vigilant and avoid consumption of raw oysters or partially cooked bivalve shellfish to prevent infection," Dr Tsui explained.

"In addition to food poisoning, norovirus can also cause acute gastroenteritis (AGE). The CHP reminded members of the public that AGE outbreaks have been steadily increasing since early January through press release last week. The latest data showed that, this year (as of February 4), a total of 29 AGE outbreaks in institutions and schools were recorded, involving a total of 206 persons. Laboratory testing indicated that over 60 per cent were caused by norovirus. Furthermore, according to the CHP's sentinel surveillance data, the AGE activity level has also shown an upward trend recently in Family Medicine Clinics, private medical practitioner clinics and child care centres/kindergartens. In addition, there have been increases in the norovirus activity in other popular travel destinations for Hong Kong citizens, including Japan and Korea. Members of the public should remain vigilant and maintain personal, environmental and food hygiene at all times to minimise the risk of being infected while travelling," Dr Tsui added.

New food poisoning clusters

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The CHP is investigating two epidemiologically linked food poisoning clusters affecting a total of four persons. The clusters involve one male and three females aged between 28 and 38. They developed abdominal pain, nausea, vomiting, diarrhoea and fever about 20 to 42 hours after having dinner at Odelice located at Shop No. 628, 6/F, New Town Plaza Phase 1, 18 Shatin Centre Street, Shatin on January 31 and February 1 respectively.

Three of the affected persons sought medical advice, and one of them required hospitalisation.A stool specimen from this patient tested positive for norovirus.All of the affected individuals are currently in stable condition.

A preliminary investigation revealed that raw oyster was the food item that the affected individuals had in common at the aforementioned restaurant. Officers of the FEHD (including personnel of the CFS and the Environmental Hygiene Branch) conducted an investigation and examined the handling processes and food hygiene at the restaurant. Food samples were also collected for testing. The CFS's field investigation revealed that the affected persons may have contracted food poisoning from consuming raw food. The CFS immediately instructed the premises concerned to suspend serving the incriminated food items and to carry out cleaning and disinfection of the premises. The officers have also provided health education related to food safety and environmental hygiene to the staff of the premises.

The investigation of the CHP and the CFS is ongoing.

Preventive measures to be taken by the public

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Norovirus infection typically causes food poisoning and AGE with symptoms including nausea, vomiting, diarrhoea, abdominal pain, low-grade fever and malaise. The symptoms are usually self-limiting and most people will get better within one to three days.

In general, norovirus is more active in winter (around December to March). As norovirus is highly contagious, individuals may become infected after being exposed to even a small amount of norovirus. The virus can be transmitted through various means, such as eating contaminated food, contacting with the vomit or excreta of infected persons, and contacting with contaminated objects. In settings where people are staying close together such as schools, elderly homes etc., there is a possibility of a large-scale outbreak.

"As the Lunar New Year holiday is approaching, members of the public have more opportunities to have parties with food delivery services or hotpot. To prevent food poisoning, apart from maintaining personal hygiene, they should also consume thoroughly washed and cooked food. For shellfish, the shells should be well scrubbed and the internal organs be removed before consumption. To prevent AGE and norovirus infection, members of public should perform hand hygiene frequently, especially before handling food or eating, and after using the toilet. Wash hands with liquid soap and water, and rub for at least 20 seconds, then rinse with water and dry with a disposable paper towel or hand dryer. Since alcohol is not effective in killing norovirus, alcohol-based handrubs are not a substitute for handwashing with soap and water," said Dr Tsui.

In addition, members of the public are reminded to maintain personal, food and environmental hygiene at all times. When dining out, one should:

Avoid eating raw seafood;

Be a discerning consumer in choosing cold dishes, including sashimi, sushi and raw oysters at a buffet;

Choose pasteurised eggs, egg products or dried egg powder for dishes that often use undercooked eggs;

Patronise only reliable and licensed restaurants;

Ensure food is thoroughly cooked before eating during a hotpot or barbecue meal;

Handle raw and cooked foods carefully and separate them completely during the cooking process;

Use two sets of chopsticks and utensils to handle raw and cooked foods;

Avoid patronising illegal food hawkers;

Drink boiled water;

Susceptible populations, including those with weakened immunity, the elderly, pregnant women and young children, are at a higher risk of foodborne diseases, so they should not consume raw or undercooked foods;

Refrain from trying to use salt, vinegar, wine or wasabi to kill bacteria as they are not effective; and

Always wash hands before eating and after going to the toilet.

Source: AI-found images

Trade instructed to suspend importing and selling of raw oysters supplied by Seojun Mulsan Co., Ltd. from Korea

The Centre for Food Safety (CFS) of the Food and Environmental Hygiene Department today (February 5) instructed the trade to suspend the import of raw oysters supplied by Seojun Mulsan Co., Ltd from Korea. The trade should stop using or selling the affected product immediately should they possess it.

A spokesman for the CFS said, "The CFS, upon recent notification by the Centre for Health Protection of the Department of Health of food poisoning cases, conducted follow-up investigations at both the restaurant and supplier levels, and found that the cases involved consumption of raw oysters supplied by Seojun Mulsan Co., Ltd. from Korea. For the sake of prudence, the CFS has immediately instructed the trade to suspend the import into and sale within Hong Kong of raw oysters supplied by Seojun Mulsan Co., Ltd. from Korea."

The CFS has also instructed the supplier and restaurants concerned to stop supplying and selling the affected raw oysters immediately, and is tracing the distribution of the product concerned. The trade should also stop using or selling the product concerned immediately should they possess it.

The spokesman pointed out that as oysters feed by filtering a large volume of seawater, pathogens can accumulate in them if they are grown in or harvested from contaminated water. Raw or partially cooked oysters are high-risk foods. Susceptible groups, such as pregnant women, young children, the elderly and people with weakened immune systems or liver diseases, should avoid eating raw oysters.

The CFS has informed the Korean authorities of the matter and will also notify the local trade. It will continue to follow up on the incident and take appropriate action to safeguard food safety and public health. An investigation is ongoing.

Source: AI-found images