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

Vladimir Gilca,Monique Douville-Fradet,Raymond Tsang,Rachid Amini,Rodica Gilca,Philippe De Wals,Martyn Kirk,France Markowski,Geneviève Deceuninck,Brigitte Lefebvre

doi:10.1371/journal.pone.0050659

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.

Highlights

Neisseria meningitidis causes both epidemic and endemic invasive meningococcal disease (IMD) worldwide
From January 1997 through December 2011, a total of 1028 IMD cases were reported to the notifiable disease registry, and 945 IMD cases to the laboratory surveillance (Table 1)
Overall discrepancy between notifiable disease registry and laboratory surveillance has been relatively stable over the study period

Summary

Introduction

Neisseria meningitidis causes both epidemic and endemic invasive meningococcal disease (IMD) worldwide. In Canada, the majority of IMD has been due to serogroup B and serogroup C over the last 20 years. In the province of Quebec, outbreaks caused by the serogroup C occurred in the early 1990s [4,5] and in 2001 [6]. Since 2002, one dose of serogroup C conjugate vaccine is offered at age 12 months. In 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

Methods

Results

Discussion

Conclusion