CHP reminds public to avoid consuming raw oysters and undercooked bivalve shellfish for the time being to prevent norovirus infection
In view of the recent surge in norovirus food poisoning cases linked to the consumption of raw oysters, the Centre for Health Protection (CHP) of the Department of Health today (February 11) reiterated its call for the public to stay alert and maintain good personal, food and environmental hygiene at all times. The public, especially the elderly, pregnant women, children and those with weakened immune systems, should refrain from consuming raw oysters and undercooked bivalve shellfish as they are at higher risk of developing complications (such as dehydration) if infected with norovirus.
The norovirus, Photo source: CDC
"The number of food poisoning cases recorded over the past few weeks has continued to rise, increasing from an average of one case per week in late December to an average of four cases per week in January. From January 18 to February 10, the CHP recorded 39 food poisoning cases, affecting 44 males and 75 females aged between 15 and 75. Nearly 90 per cent (35 cases) were associated with norovirus, affecting 105 persons. Epidemiological investigations showed that all the individuals affected by the abovementioned food poisoning cases related to norovirus had consumed raw oysters during the incubation period. Six of them required hospitalisation. All are in stable condition. The CHP has notified the Centre for Food Safety (CFS) of the Food and Environmental Hygiene Department (FEHD) of all food poisoning cases for appropriate follow-up and source tracing. Investigations are ongoing," 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 or undercooked oysters are considered a high-risk food. Persons who consume contaminated or undercooked oysters may contract food-borne diseases, such as norovirus, hepatitis A virus or other bacteria. During the Lunar New Year, people usually gather for meals with relatives and friends. I particularly remind the public that only thoroughly cooked food, especially shellfish, should be consumed, whether dining at home or in restaurants, to avoid contracting enteric diseases. Norovirus cannot be killed by alcoholic beverages, lemon juice or wasabi. When cooking oysters in a hot pot or on the grill, ensure that they are thoroughly cooked to effectively minimise the risk of norovirus infection. Given the recent increase in norovirus activity and epidemiological data indicating that most food poisoning cases are related to raw oyster consumption, the CFS of the FEHD is investigating the source of raw oysters. Hence, members of the public should not take the risk of consuming undercooked oysters," Dr Tsui explained.
"It is worth noting that norovirus is highly contagious. Individuals infected with norovirus through contaminated food can spread the virus to others through person-to-person contact or environment contaminated by vomitus. In addition to causing food poisoning, norovirus is also one of the primary causes of acute gastroenteritis (AGE). According to our surveillance data, the AGE activity level in Hong Kong has been rising since early January. The latest data showed that, as of February 10, a total of 38 AGE outbreaks in institutions and schools were recorded so far this year, involving 294 persons. Laboratory testing indicated that over 75 per cent of the outbreaks were caused by norovirus. Additionally, norovirus activity has increased in other popular travel destinations for Hong Kong citizens, including Japan and Korea. Surveillance data from Korea showed that the norovirus activity has reached its highest level in nearly five years for this time of year. Members of the public should remain vigilant and maintain good personal, environmental and food hygiene when travelling abroad and pay attention to minimise the risk of infection," Dr Tsui added.
To prevent AGE and norovirus infection, members of the public should perform hand hygiene frequently. Since alcohol is not effective in killing norovirus, alcohol-based handrubs are not a substitute for handwashing with soap and water, 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.
Members of the public may visit the CHP's dedicated webpages for the prevention of Norovirus Infection and Viral Gastroenteritis.
The raw oysters, Photo by Bastille Post
