Authorities investigating recent spike in Group B Streptococcus infections, previously linked to raw fish

SINGAPORE — The authorities are investigating a recent spike in cases of Group B Streptococcus (GBS) infections, which had in the past been associated with the consumption of raw freshwater fish.

There were 50 reports of GBS cases from public hospitals in July, compared with an average of 25 GBS cases per month from January to June, the Ministry of Health (MOH) and Singapore Food Agency (SFA) said in a joint press release on Sunday (Aug 30).

The agencies said investigations showed that 18 of the cases reported in July were GBS Type III ST283 — a more infectious strain. This compares with an average of four cases per month from April to June.

The majority of the cases with GBS Type III ST283 were aged 65 and above. Most have since been discharged and have recovered from the infection while one died due to an unrelated cause, the agencies added.

MOH and SFA said they are collecting information on the affected individuals’ food history and conducting field investigations at various locations, to determine possible sources of GBS in these cases.

"Based on SFA’s routine sampling and testing of fish samples for GBS between May 2019 and August 2020, the presence of ST283 has not been detected. SFA also conducted inspections at food stalls visited by recent cases and found that none of the stalls sold any ready-to-eat raw fish dishes," MOH and SFA said.

A GBS outbreak in 2015 that affected over 300 people and caused two deaths led the authorities to ban the use of freshwater fish in ready-to-eat raw fish dishes.

SFA is issuing reminders to retail food establishments to adhere to the ban, which has been in force since December 2015.

Food establishments selling ready-to-eat raw fish are also reminded to ensure good hygiene practices and proper handling of the ready-to-eat raw fish. MOH has also alerted doctors to remain vigilant and report suspected invasive GBS cases.

The agencies advise members of the public who choose to consume ready-to-eat raw fish to exercise caution.

HEALTH ADVISORY

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 cause serious infection such as sepsis or blood poisoning, which can lead to death. Symptoms include fever, chills and low alertness, the United States Centers for Disease Control and Prevention said.

GBS may also occasionally cause invasive infections of the skin, joints, heart and brain. Symptoms vary depending on the part of the body infected. If it infects the lungs, the person may have pneumonia, chest pain and difficulty breathing. 

MOH said that the risk factors for GBS infection include underlying chronic or co-morbid conditions, such as diabetes. Transmission may also occur during childbirth.

Most GBS infections are treatable with antibiotics.

GBS infections have previously been associated with the consumption of raw freshwater fish, the ministry added.

Raw food is likely to contain more bacteria compared to well-cooked food.

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. As a general precaution, vulnerable groups of people, especially young children, pregnant women, elderly persons, or people with chronic illness such as diabetes, may be more susceptible and should exercise caution by avoiding the consumption of raw food. Individuals can also reduce their risk of infection by:

• thoroughly cooking food;

• washing hands and kitchen utensils such as knives and cutting boards thoroughly before handling food; and

• using separate sets of knives and cutting board for raw and cooked food.