Food Safety Focus (129th Issue, April 2017) – Incident in Focus
Review of Foodborne Disease Outbreaks Related to Food Premises and Food Business in 2016
Reported by Dr. Stella YAU, Medical & Health Officer,
Food Incidents Response & Management Unit,
Centre for Food Safety
This article reviews the food poisoning outbreaks related to local food premises and food business reported to the Centre for Food Safety (CFS) in 2016.
Foodborne Disease Outbreaks Related to Local Food Premises and Food Business
In collaboration with the Department of Health (DH), the CFS is responsible for the investigation and control of foodborne disease outbreaks related to local food premises and food business that are referred from the Centre for Health Protection (CHP) of DH. The annual number of referrals decreased generally from 2006 to 2010 and has since remained relatively stable (see Figure). In 2016, the CFS received 201 such referrals from CHP, a record low. These 201 cases affected 1011 persons.
Number of foodborne disease outbreaks related to food premises and food business and the corresponding number of persons affected from 2006 to 2016.
Causative Agents and Contributing Factors
For the cases with the suspected microbiological causative agents being identified, bacterial foodborne agents remained the leading causes (73%) of all foodborne disease outbreaks investigated by the CFS in 2016, with Salmonella, Vibrio parahaemolyticus and Bacillus cereus being the top three incriminated bacterial pathogens. For the viral causes, norovirus, associated with the consumption of raw/undercooked bivalves, was found to be the only incriminated viral agent causing around 18% of all the outbreak referrals.
Of the 201 cases investigated last year, the most frequently identified contributing factors are consumption of raw food (e.g. oyster with norovirus), contamination by food handlers or utensils and inadequate cooking.
We discuss below are two major food poisoning outbreaks that occurred in 2016 to illustrate the importance of good hygiene and food safety practices in safeguarding food safety.
12 Clusters of Food Poisoning Outbreaks Related to the Sauces
In April 2016, 12 clusters of food poisoning outbreaks in relation to a restaurant affecting a total of 32 persons were reported to the CFS. Stool samples of four of the victims were tested positive for group D Salmonella. Epidemiological investigation of these clusters suggested that food poisoning was related to the consumption of four different incriminated food items, all of them contained sour cream sauce as ingredient. A food sample of this sauce was tested positive for group D Salmonella. In addition to sour cream sauce, samples of guacamole sauce collected during investigation were also tested positive for group D Salmonella. Further sample collected at the supplier evel were tested negative for Salmonella and other food poisoing ogranisms. Stool samples of two food handlers were tested positive for Salmonella group B and group C respectively, but they were regarded as incidental findings.
All the clusters happened within four consecutive days and before the visit of the Food and Environmental Hygiene Department (FEHD). Our field investigation revealed that during this period, one large bottle of sour cream sauce was re-packed into smaller bottles and multiple handling occurred during the re-packing procedure. The incriminated sour cream sauce was the probable vehicle for transmission of this food poisoning outbreak. Lapse of food hygienic practices by food handlers, cross contamination with other foods, re-packing and continual topping-up of sour cream sauces posed a risk of cross-contamination.
Health advice was given to the restaurant operators and their staff.
Sale of the incriminated food items and all related sauces including the sour cream sauce was suspended immediately to curb further cases. No further outbreaks were received afterwards.
Food Poisoning Outbreaks Related to Consumption of Buffet Meals
In June 2016, 22 clusters of food poisoning outbreaks related to consumption of buffet meals in a restaurant were reported to the CFS, a total of 108 persons reported to be affected. Six victims had submitted stool specimens for testing and all were tested positive for Vibrio parahaemolyticus (VP). VP is a common food poisoning organism and often found in the marine environment and seafood.
Epidemiological assessment and field investigation indicated that some cold served seafood provided at the buffets were possible illness sources. On-site investigation revealed that the ready-to-eat frozen cooked lobster was defrosted in a basin next to another basin for washing raw seafood. Cross-contamination by raw seafood might have contributed to the outbreak. However, the cold served RTE seafood samples, including lobsters, cold shrimps and cold crabs collected at the restaurants and supplier level showed negative results
Health advice on food, environmental and personal hygiene was given to the restaurant operators and their staff. Follow up visits were also conducted to ensure proper implementation of food safety measures. No additional cases have been reported after the control measures were implemented.
Both food poisoning outbreaks discussed above demonstrated that cross-contamination posed high risk to food safety. Cross-contamination and the resulting food poisoning could, however, be prevented by improving the training to food handlers, one of the key elements of good food hygiene practice.
Although the number of food poisoning outbreaks remains at a relatively low level over the past few years, there is no room for complacency. While the government will continue to be vigilant in safeguarding food safety, the trade and the public are advised to adopt and adhere to the "Five Keys to Food Safety" in order to prevent the occurrence of future outbreaks. Moreover, the management of food premises is encouraged to provide more training and monitoring to staff to enhance food safety.