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. 2012;7(11):e50659.
doi: 10.1371/journal.pone.0050659. Epub 2012 Nov 29.

The changing epidemiology of meningococcal disease in Quebec, Canada, 1991-2011: potential implications of emergence of new strains

Rodica Gilca  1 , Geneviève Deceuninck, Brigitte Lefebvre, Raymond Tsang, Rachid Amini, Vladimir Gilca, Monique Douville-Fradet, France Markowski, Philippe De Wals
Affiliations

The changing epidemiology of meningococcal disease in Quebec, Canada, 1991-2011: potential implications of emergence of new strains

Rodica Gilca et al. PLoS One. 2012.

Abstract

Background: 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.

Methodology: IMD 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.

Results: Yearly 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.

Conclusion: Important 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.

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Conflict of interest statement

Competing Interests: The authors have the following conflicts: RG received a research grant for unrelated study from Pfizer; PDW received research grants, honoraria and reimbursements of travel expenses from vaccine manufacturers Glaxo-Smith-Kline, Novartis, Sanofi Pasteur, Merck and Pfizer; VG received research grants, honoraria and/or reimbursements of travel expenses from Novartis, Glaxo-Smith-Kline, Merck and Pfizer; GD, BL, RT, RA, MDF, and FM have declared that no competing interests exist. This does not alter the authors’ adherence to all the PLOS ONE policies on sharing data and materials.

Figures

Figure 1
Figure 1. IMD incidence in Quebec, 1991–2011.
Figure 2
Figure 2. IMD incidence by age group in Quebec according to laboratory surveillance, 1997–2011.
A. Overall IMD incidence. B. Serogroup B incidence.
Figure 3
Figure 3. Number and proportion of different clonal complexes among culture-positive serogroup B isolates, 2003–2011.
See this image and copyright information in PMC

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