Meningococcal Meningitis Surveillance in the African Meningitis Belt, 2004-2013

Abstract

Background: An enhanced meningitis surveillance network was established across the meningitis belt of sub-Saharan Africa in 2003 to rapidly collect, disseminate, and use district weekly data on meningitis incidence. Following 10 years' experience with enhanced surveillance that included the introduction of a group A meningococcal conjugate vaccine, PsA-TT (MenAfriVac), in 2010, we analyzed the data on meningitis incidence and case fatality from countries reporting to the network.

Methods: After de-duplication and reconciliation, data were extracted from the surveillance bulletins and the central database held by the World Health Organization Inter-country Support Team in Burkina Faso for countries reporting consistently from 2004 through 2013 (Benin, Burkina Faso, Chad, Democratic Republic of Congo, Ghana, Côte d'Ivoire, Mali, Niger, Nigeria, Togo).

Results: The 10 study countries reported 341 562 suspected and confirmed cases over the 10-year study period, with a marked peak in 2009 due to a large epidemic of group A Neisseria meningitidis (NmA) meningitis. Case fatality was lowest (5.9%) during this year. A mean of 71 and 67 districts annually crossed the alert and epidemic thresholds, respectively. The incidence rate of NmA meningitis fell >10-fold, from 0.27 per 100,000 in 2004-2010 to 0.02 per 100,000 in 2011-2013 (P < .0001).

Conclusions: In addition to supporting timely outbreak response, the enhanced meningitis surveillance system provides a global overview of the epidemiology of meningitis in the region, despite limitations in data quality and completeness. This study confirms a dramatic fall in NmA incidence after the introduction of PsA-TT.

Keywords: Africa; meningitis; surveillance.

Figure 1.

Incidence rate of suspected and confirmed cases of meningitis in the African meningitis belt by year (solid line) and case fatality (dotted line), 2004–2013.

Figure 2.

Number of suspected and confirmed meningitis cases by week in the African meningitis belt of 2004 (red), 2005 (orange), 2006 (yellow), 2007 (light green), 2008 (green), 2009 (light blue), 2010 (blue), 2011 (purple), 2012 (pink), and 2013 (gray).

Figure 3.

Incidence rate of pathogens per 100 000 population among positive cerebrospinal samples before (2004–2010) (blue) and after (2011–2013) (red) the introduction of vaccination with PsA-TT (MenAfriVac). Abbreviations: Hib, Haemophilus influenzae type b; Nm, Neisseria meningitidis; NmA, Neisseria meningitidis group A; NmW, Neisseria meningitidis group W; Spn, Streptococcus pneumoniae.