Health authorities investigating spike in Group B Strep cases, advise caution when consuming raw fish

Health authorities investigating spike in Group B Strep cases, advise caution when consuming raw fish

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File photo of a plate of raw freshwater fish. 

SINGAPORE: Members of the public who consume raw fish should exercise caution, Singapore's health authorities warned as they investigate a spike in the number of Group B Streptococcus (GBS) cases. 

Fifty cases of GBS were reported by public hospitals in July, up from an average of 25 cases a month between January and June, the Ministry of Health (MOH) and Singapore Food Agency (SFA) said in a press release on Sunday (Aug 30).

Laboratory investigations found that 18 of the cases reported in July were GBS Type III ST283. This compares with an average of four cases per month from April to June.

The majority of the cases were patients aged 65 and above. Most have since recovered and have been discharged from hospital, although one patient died of an unrelated cause, MOH said.

In 2015, the same strain of the bacteria landed more than 160 people in hospital with fever and invasive infections, such as meningitis, after they consumed yusheng, a raw fish dish typically eaten with congee.

File photo of raw fish and porridge.

Two died from the infection and one of the patients, former technician Tan Whee Boon, had to have all his limbs amputated.  

Following the outbreak, food outlets were banned from selling raw freshwater fish, after tests showed that such fish had higher bacterial contamination than saltwater fish, and are likely to present higher risks of infection when consumed raw.

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For the recent cases, health authorities are collecting information on the patients’ food history and conducting field investigations at various locations to determine possible sources of GBS.

SFA said it has not detected the ST283 bacteria strain in its routine testing of fish samples between May 2019 and August this year.

It also inspected food stalls visited by the patients and found that none of the stalls sold ready-to-eat raw fish dishes.

Ready-to-eat raw fish are intended for raw consumption, and generally sold and marketed separately from other raw fish intended for cooking.

Still, the agency said it is issuing reminders to retail food outlets to adhere to the ban on the sale of raw freshwater fish. Those selling ready-to-eat raw fish have also been reminded to ensure good hygiene practices and proper handling of food. 

The health ministry said it has also alerted doctors to report suspected invasive GBS cases.

READ: Bacteria in 2015 GBS outbreak is widespread in Southeast Asia: Researchers

GBS is a common bacterium found in the human gut and urinary tract of about 15 to 30 per cent of adults without causing disease. However, it may occasionally cause invasive infections of the skin, joints, heart and brain. 

The risk factors for GBS, which is usually treatable with antibiotics, include underlying chronic or co-morbid conditions, such as diabetes. Transmission may also occur during childbirth. 

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"Members of the public who choose to consume ready-to-eat raw fish must be aware of the risks involved. Cooking raw food well is still the most effective way to kill bacteria," said MOH and SFA.

They cautioned that vulnerable groups of people, especially young children, pregnant women, elderly people or those with chronic illnesses such as diabetes may be more susceptible and should avoid eating raw food.

People can also reduce their risk of infection by washing their hands and kitchen utensils thoroughly before handling food, and using separate sets of knives and cutting boards for raw and cooked food.

Source: CNA/zl(cy)