The Changing Epidemiology of Meningococcal Disease in Quebec, Canada, 1991–2011: Potential Implications of Emergence of New Strains

Abstract

BackgroundIn order to inform meningococcal disease prevention strategies, we analysed the epidemiology of invasive meningococcal disease (IMD) in the province of Quebec, Canada, 10 years before and 10 years after the introduction of serogroup C conjugate vaccination.MethodologyIMD cases reported to the provincial notifiable disease registry in 1991–2011 and isolates submitted for laboratory surveillance in 1997–2011 were analysed. Serogrouping, PCR testing and assignment of isolates to sequence types (ST) by using multilocus sequence typing (MLST) were performed.ResultsYearly overall IMD incidence rates ranged from 2.2–2.3/100,000 in 1991–1992 to 0.49/100,000 in 1999–2000, increasing to 1.04/100,000 in 2011. Among the 945 IMD cases identified by laboratory surveillance in 1997–2011, 68%, 20%, 8%, and 3% were due to serogroups B, C, Y, and W135, respectively. Serogroup C IMD almost disappeared following the implementation of universal childhood immunization with monovalent C conjugate vaccines in 2002. Serogroup B has been responsible for 88% of all IMD cases and 61% of all IMD deaths over the last 3 years. The number and proportion of ST-269 clonal complex has been steadily increasing among the identified clonal complexes of serogroup B IMD since its first identification in 2003, representing 65% of serogroup B IMD in 2011. This clonal complex was first introduced in adolescent and young adults, then spread to other age groups.ConclusionImportant changes in the epidemiology of IMD have been observed in Quebec during the last two decades. Serogroup C has been virtually eliminated. In recent years, most cases have been caused by the serogroup B ST-269 clonal complex. Although overall burden of IMD is low, the use of a vaccine with potential broad-spectrum coverage could further reduce the burden of disease. Acceptability, feasibility and cost-effectiveness studies coupled with ongoing clinical and molecular surveillance are necessary in guiding public policy decisions.

Diversity of meningococci associated with invasive meningococcal disease in the Republic of Ireland over a 19 year period, 1996-2015

“…Furthermore, the genotyping data presented here supports the lack of reported epidemiological links between cases from which an isolate was received. Similar increases in genotypic diversity among IMD isolates recovered over similar time frames were also observed in Canada [64], the Netherlands [48] and Belgium [36]. This overall trend of increased diversity for menB masks the transient but marked dips in diversity observed especially during EY2005/2006 and to a lesser extent in EY2000/2001, EY2010/2011 and EY2012/2013.…”

Enhanced surveillance of invasive meningococcal disease in Canada, 2006-2011

“…Studies of population biology of invasive N. meningitidis strains by MLST have revealed a predominant clone of serogroup B ST-269 in the province of Quebec leading to an increase in the incidence of IMD (23)(24)(25). In the neighbouring province of Ontario, no similar increase of this strain or cases of disease have been observed (26,27).…”

Response to the changing epidemiology of meningococcal disease in North America 1945-2010

“…In fact in some provinces, the incidence of serogroup B has actually increased since the introduction of serogroup C conjugate immunization programs. 5 In other provinces, the incidence of disease continues to exhibit cyclical patterns, but nowhere have we observed a decline in serogroups B, Y and W135. 2,6,7 (4) The use of vaccination: Canada has been pro-active in its control of IMD.…”