Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2025 Jun 24:153:e76.
doi: 10.1017/S0950268825100186.

A large outbreak of invasive Group B Streptococcus Sequence Type 283 infection linked to physical contact of freshwater fish

Hoi-Kei Wong  1 , Kai-Lok Lam  1 , Alan Ka-Lun Tsang  2 , Derek Ling-Lung Hung  2 , Tonny Ng  1 , Albert Ka-Wing Au  1 , Edwin Lok-Kin Tsui  3
Affiliations

A large outbreak of invasive Group B Streptococcus Sequence Type 283 infection linked to physical contact of freshwater fish

Hoi-Kei Wong et al. Epidemiol Infect. .

Abstract

Invasive Group B Streptococcus (GBS) infection caused by the highly virulent Sequence Type 283 (ST283) strain has been linked to consumption of raw freshwater fish. In late summer 2024, enhanced surveillance in Hong Kong detected a surge of invasive ST283 cases.A retrospective case-control study was conducted involving all invasive GBS patients reported during August to September 2024. Data were collected through standardised interviewer-administered questionnaires. Cases were defined as patients infected with the ST283 strain, while controls had non-ST283 strains. A multivariate logistic regression analysis was conducted to determine the risk factors.Among 170 invasive GBS patients, 131 (77%) were identified as cases and 39 (23%) as controls. Physical handling of raw freshwater fish was found to be the strongest risk factor for ST283 infection (adjusted odds ratio: 8.4, 95% confidence interval: 1.4-50.1).This study represents the first epidemiological evidence specifically linking physical contact with raw freshwater fish to an increased risk of invasive GBS ST283 infection. Effective interdepartmental coordination, intensive public health education, active surveillance, and prompt environmental interventions effectively mitigated this large outbreak. The findings underscore the need for sustainable preventive strategies targeting high-risk fish handling practices, particularly during warm periods favouring environmental proliferation of ST283.

Keywords: Group B Streptococcus; Sequence Type 283; freshwater fish; physical contact.

PubMed Disclaimer

Conflict of interest statement

The authors declare none.

Figures

Figure 1.
Figure 1.
Epidemic curve of the ST283 cases.
See this image and copyright information in PMC

References

    1. Food and Agriculture Organization of the United Nations (2021) Risk Profile. Group B Streptococcus (GBS) Streptococcus agalactiae Sequence Type 283 (ST283) in Freshwater Fish. Bangkok.
    1. Ip M, et al. (2006) Identification of a Streptococcus agalactiae serotype III subtype 4 clone in association with adult invasive disease in Hong Kong. Journal of Clinical Microbiology 44(11), 4252–4254. - PMC - PubMed
    1. Barkham T, et al. (2019) One hypervirulent clone, sequence type 283, accounts for a large proportion of invasive Streptococcus agalactiae isolated from humans and diseased tilapia in Southeast Asia. PLoS Neglected Tropical Diseases 13(6), e0007421. - PMC - PubMed
    1. Tan S, et al. (2016) Group B streptococcus serotype III sequence type 283 bacteremia associated with consumption of raw fish, Singapore. Emerging Infectious Diseases 22(11), 1970–1973. - PMC - PubMed
    1. Rajendram P, et al. (2016) Group B streptococcus sequence type 283 disease linked to consumption of raw fish, Singapore. Emerging Infectious Diseases 22(11), 1974–1977. - PMC - PubMed

MeSH terms