SINGAPORE - The authorities are looking into a recent spike in bacterial infections that were associated with eating raw freshwater fish in the past.
In a Friday (Aug 28) circular to doctors seen by The Straits Times, Ministry of Health (MOH) medical services director Kenneth Mak said 50 cases of invasive Group B Streptococcus (GBS) were reported by public hospitals last month.
This is twice the average monthly figure of 25 from earlier this year.
Laboratory tests showed that 18 of these cases were infected by GBS Type III ST283, and the profile of these patients is similar to that of those who were infected by the same bacteria in a 2015 outbreak caused by eating raw freshwater fish. The National Environment Agency had subsequently banned the sale of such ready-to-eat fish by retail food places.
Most of the latest 18 cases were aged 65 years and above, and developed septicaemia or bacteraemia, commonly known as blood poisoning. All of them were Chinese, said Associate Professor Mak in the circular.
Most of the patients have been discharged but one patient died from an unrelated cause.
"All medical practitioners are requested to remain vigilant and to refer all patients with symptoms suggestive of severe GBS to a hospital for assessment," he said.
It is not known if the July infections are linked to eating raw freshwater fish. ST has contacted the MOH and the Singapore Food Agency for more information.
In 2015, the highly infectious strain of bacteria caused an outbreak of blood poisoning in over 160 people, who suffered from fever, joint infection and meningitis.
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, said Prof Mak.
It may occasionally cause serious infections, and symptoms include fever, chills and low alertness.
Doctors who spoke to ST on Saturday confirmed that they had received the circular and warned that the disease could be easily misdiagnosed as Covid-19 or dengue fever.
Dr Leong Hoe Nam, an infectious disease specialist at Mount Elizabeth Novena Hospital, said this is because the initial symptoms are "remarkably similar".
"You don't want to put a strain on the existing system, already laden with Covid-19 and dengue... It confuses the picture," he said.
Dr Leong added that he has seen at least three GBS cases in recent weeks, and said 50 cases was a lot, especially considering milder cases may not be identified.
Similarly, Dr Raymond Ong, a general practitioner at Intemedical 24 Hour Clinic, said the symptoms are the same as many other infections. Like Covid-19 and dengue, most people generally recover, but the infection is much more dangerous for the elderly and those who have pre-existing symptoms, he added.
Both doctors stressed the importance of hygiene in food preparation and consumption.
Dr Ong said: "The disease is transmitted through the faecal-oral route, so hand hygiene is very important."
He advised consumers to wash their hands and not to cross-contaminate cooked and uncooked food.
Dr Leong agreed, saying: "If we don't clean food with GBS, we end up as food for the GBS."