Genetically distinct Hajj and South American-related strains of serogroup W Neisseria meningitidis causing invasive meningococcal disease in Ontario, Canada, January 1, 2015 to June 30, 2024

Courtney Meilleur; Julianne Kus; Christine Navarro; Vinita Dubey; Jay Lucidarme; Ray Borrow; Raymond S W Tsang

doi:10.1016/j.jiph.2025.102728

Genetically distinct Hajj and South American-related strains of serogroup W Neisseria meningitidis causing invasive meningococcal disease in Ontario, Canada, January 1, 2015 to June 30, 2024

J Infect Public Health. 2025 Mar 1;18(5):102728. doi: 10.1016/j.jiph.2025.102728. Online ahead of print.

Authors

Courtney Meilleur¹, Julianne Kus², Christine Navarro³, Vinita Dubey⁴, Jay Lucidarme⁵, Ray Borrow⁵, Raymond S W Tsang⁶

Affiliations

¹ Vaccine Preventable Bacterial Diseases, National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg, Manitoba, Canada.
² Public Health Ontario, Toronto, Ontario, Canada; Department of Laboratory Medicine and Pathobiology, University of Toronto, Toronto, Ontario, Canada.
³ Public Health Ontario, Toronto, Ontario, Canada.
⁴ Toronto Public Health, Toronto, Ontario, Canada; Dalla Lana School of Public Health, University of Toronto, Ontario, Canada.
⁵ Meningococcal Reference Unit, UK Health Security Agency, Manchester Medical Microbiology Partnership, Manchester Royal Infirmary, Manchester, UK.
⁶ Vaccine Preventable Bacterial Diseases, National Microbiology Laboratory Branch, Public Health Agency of Canada, Winnipeg, Manitoba, Canada. Electronic address: raymond.tsang@phac-aspc.gc.ca.

PMID: 40056891
DOI: 10.1016/j.jiph.2025.102728

Abstract

Objectives: To characterize the recent trends in serogroup W isolates from invasive meningococcal disease (IMD) cases (MenW) in Ontario, Canada since 2015.

Methods: IMD case isolates in Ontario between January 1, 2015 and June 30, 2024 were examined by phenotypic and genetic methods for possession of vaccine antigen genes and clonal characteristics. MenW ST-11 clonal complex (CC) strains were compared against global MenW isolates by core-genome multi-locus sequence typing (cgMLST).

Results: The percentage of culture-confirmed IMD caused by MenW in Ontario increased from 10 % in 2015-40.9 % in the first half of 2024, consisting entirely of strains belonging to the ST-11 CC. cgMLST comparison of the Ontario invasive MenW isolates versus international MenW ST-11CC strains showed that the Ontario isolates were related to those found globally, with a recent cluster of eight cases from one city due to a strain highly related to international Umrah outbreak strains. Most MenW IMD cases (60 %) occurred in individuals older than 40 years of age and the majority (83.3 %) predicted to express antigens covered by the 4CMenB vaccine.

Conclusions: Multiple different introductions of international MenW strains likely accounted for the recent shift towards invasive MenW disease in Ontario.

Keywords: Genetic strains; Invasive meningococcal disease; ST-11 complex; Serogroup W.