A bacterial outbreak in Hong Kong has been linked to raw freshwater fish, with 40 cases reported in a month. Photo: Antony DicksonHong Kong health authorities have issued a warning about the potential dangers of raw freshwater fish after 40 people contracted a deadly bacterial infection linked to the food.
The Centre for Health Protection (CHP) has identified 13 new cases of Group B Streptococcus, bringing the total to 40 in a month. The CHP is investigating the source of the ST283 infection outbreak, which appears to be linked to contact with raw freshwater fish.
The centre said the 40 patients’ onset date of disease was between August 8 and September 5. Thirty of them had underlying illnesses.
Two patients with underlying illnesses had died, while three were in a serious condition. Twenty-five were in a stable condition, and the 10 others had been discharged.
Of the 13 new cases, seven were men and six were women, aged between 35 and 94. They mainly suffered from sepsis and joint abscesses.
“Together with the 27 cases of ST283 infection announced on September 13, this cluster involves a cumulative total of 40 patients residing in 18 districts throughout [Hong Kong],” it said.
“The CHP’s analysis of samples of other recently admitted patients is still in progress and it cannot rule out that the number of cases will further increase.”
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Group B Streptococcus is a bacteria commonly seen in the intestinal, urinary and reproductive tracts.
It is usually not harmful and does not lead to any symptoms, but can potentially cause infections in blood, bones, lungs or the protective membranes covering the brain and spinal cord.
In October 2021, at least 80 cases of Group B Streptococcus infections were recorded in Hong Kong, with two people in a 32-strong cluster dying.
The CHP last week said in the 2021 outbreak, a cluster of more than 50 cases of ST283 was found to be associated with contact with raw freshwater fish or consumption of undercooked ones.
The centre on Monday said its investigations into the latest outbreak found that 31 patients had come into contact or handled raw freshwater fish before the onset of their symptoms, with five reporting they had hand wounds when doing so.
Six patients could not rule out that they had eaten undercooked freshwater fish, it said, while the exposure history of the remaining three was still being investigated.
None of the patients worked as fishmongers or in jobs related to fish culture, it added.
The centre said the affected fish came from 23 markets in 11 districts so the issue could involve the wholesale level.
It said it had found that the genetic sequence of samples collected from a retail freshwater fish stall matched those found in some patients.
“The CHP immediately teamed up with the Agriculture, Fisheries and Conservation Department to conduct an inspection in the Freshwater Fish Market under the Cheung Sha Wan Wholesale Food Market, and collect environmental samples for testing and analysis,” it said.
“The laboratory analysis is still in progress. So far, no abnormality has been observed regarding the freshwater fish in the wholesale fish markets.”
Medical surveillance on more than 200 workers had been conducted and all of them were not symptomatic, it added, while the Food and Environmental Hygiene Department had enhanced the cleansing and disinfection of relevant markets.
Members of the public should wear gloves when touching or handling raw freshwater fish, it said.
“If symptoms such as [an] inflamed wound and fever develop, they should seek medical attention promptly,” the centre warned.
“The public should refrain from consuming undercooked freshwater fish.”