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Bacteria outbreak: Stalls told to stop selling Chinese-style raw-fish dishes

SINGAPORE — Food stalls here have been ordered to stop selling Chinese-style raw-fish dishes until they can comply with stipulated guidelines, after investigations by the Ministry of Health (MOH) found a definite link between eating these dishes and Group B Streptococcus (GBS) infection, which can potentially cause permanent disability and even death in severe cases.

Bacteria outbreak: Stalls told to stop selling Chinese-style raw-fish dishes

File photo of raw fish served with congee. Photo: Channel NewsAsia

SINGAPORE — Food stalls here have been ordered to stop selling Chinese-style raw-fish dishes until they can comply with stipulated guidelines, after investigations by the Ministry of Health (MOH) found a definite link between eating these dishes and Group B Streptococcus  (GBS) infection, which can potentially cause permanent disability and even death in severe cases. 

To date, two persons have died from GBS infections this year, said MOH today (Nov 27), without providing details. One of the cases was not linked to the ongoing outbreak, and the other is being investigated.

MOH said it has been notified of 355 cases of GBS infections so far. Of these, about 150 cases had the Sequence Type (ST) 283 strain which causes Type III GBS disease. In comparison, there were, on average, 150 cases of GBS infections per year from 2011 to last year. 

The consumption of Chinese-style ready-to-eat raw-fish dishes was found to be associated with Type III GBS disease, said the National Environment Agency (NEA) in a joint media briefing yesterday with the MOH and the Agri-Food and Veterinary Authority of Singapore (AVA). MOH had said previously it has not found any links between the GBS infection and the consumption of Japanese raw meat or fish dish sashimi. Examples of popular Chinese-style raw-fish dishes are “yusheng”, which is usually eaten during Chinese New Year, and raw-fish porridge.

Over 70 stalls selling Chinese-style raw fish dishes have been identified by the authorities. NEA met with the owners of some of these stalls to brief them on its directive and guidelines, which include buying fish from suppliers which can provide certification on the health of the fish from authorities in the country of origin. Other measures include proper cold chain management, such as keeping fish for raw consumption chilled at the right temperature, and proper hygiene practices like using separate kitchen tools for preparing raw fish. 

NEA said it has ruled out food handlers as the source of the bacteria. Tests on stool samples from 82 food handlers and fishmongers from retail food establishments, market stalls and wholesalers found that they did not carry the ST283 strain. Contamination of the fish could have occurred along the food chain supply, the probe concluded. 

The authorities began investigations following reports in July that there was a spike in local GBS infections. Within the same month, NEA issued an advisory to food stalls, asking them to temporarily stop the sale of raw fish dishes made from Song fish and Toman fish. Since then, the number of GBS cases notified to MOH has decreased to “a usual baseline of less than 5 per week and continues to remain low”, the ministry said. Most of these cases were not due to raw fish consumption.  

Between August and last month, the AVA and the NEA carried out tests on 400 fish samples from various species and across the food chain supply including fishery ports, wet markets, fresh produce section of supermarkets, and retail food establishments.

A fifth of the samples were found to contain the GBS bacteria, and 4.1 per cent tested positive for the ST283 strain. 

Infectious disease experts TODAY spoke to pointed out that GBS bacteria is found naturally on fish and handling practices could have led to cross-contamination where fish meant to be eaten raw were mixed with fish for cooking and carrying the ST283 strain. 

Dr Leong Hoe Nam, from the Rophi Clinic in Mount Elizabeth Novena Specialist Centre, said: “Someone must have started a new practice of handling the fish in the recent year and it’s still ongoing. It could be very harmless handling of just using the same box (to hold the fish) and then the cross-contamination occurred.” 

The particular strain could also be causing the spike in GBS infections because it seems to be associated with “greater virulence or greater deadliness”, said Dr Hsu Li Yang, a physician at the ID Clinic in Mount Elizabeth Novena Specialist Centre. 

Mr Derek Ho, NEA’s director-general of environmental public health, reiterated that most food in fisheries and markets here are not meant for raw consumption. “They’re meant for cooking… If you want to eat food that’s raw, you should ensure they are procured from proper sources,” he said. Some supermarkets have dedicated counters for selling raw products, he noted. 

However, experts felt that food stalls would face difficulties in following NEA’s guidelines. As a result, most could stop selling the dishes, they noted. Dr Hsu said: “(Food stalls) have to be able to trace the source of the fish down to how they store it, how they serve it and prepare it… Even if they get it from a supplier who can tick all these boxes for them, they still have to go through great lengths in terms of how they store the fish in the hawker stall and prepare it.” 

Dr Leong described NEA’s directive to the food stalls as “a right order but... a tall order”. “It’s good to come up with some protocols but implementation will be extremely difficult… It requires a higher understanding of science, and it’s a new level of understanding and education,” he said.

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