Abstract
BackgroundThe epidemiology of pneumococcal meningitis in the African ‘meningitis belt’ is poorly studied. In order to ensure an effective vaccination strategy and post-vaccination surveillance, we examined the serotype distribution patterns of pneumococcal meningitis in Niger over the period 2003–2011.MethodsCerebrospinal fluid (CSF) samples were collected from different health facilities throughout Niger in the frame of the national microbiological surveillance of meningitis. Determination of the serotype of CSF positive for pneumococci was performed using a sequential multiplex PCR method (SM-PCR) adapted with a national algorithm in which 32 different serotypes were covered and grouped into eight consecutive PCR.ResultsThe SM-PCR assay could predict the Sp serotype for 779 CSF (88.7%), 98 CSF (11.3%) were not-typeable in our national-adapted algorithm. In total, 26 different serotypes were identified. Serotype 1 (n = 393) was the most prevalent and accounted for 45.3% of infections, followed by serogroups/serotypes 12F/(12A)/(44)/(46) (7.3%), 6/(6A/6B/6C/6D) (5.4%), 14 (5.2%), 5 (4.6%), 23F (4.2%), 45 (3.6%), 2 (3.1%), 18/(18A/18B/18C/18F) (2.9%) and 17 others serotypes with a prevalence of less than 2%. The proportion of serotype 1 in infants(<2 years old) represented only 4.3% of the cases affected by this serotype. In contrast, serotypes 5, 6, 14, 19A and 23F were only detected in very young children.ConclusionsThe proportion of serotype 1 in the pneumococcal meningitis cases and the theoretical vaccine coverage across all age groups advocates for the introduction of a conjugate vaccine (PCV10 or 13) into the Expanded Programme on Immunization (EPI) in Niger. Post-vaccine introduction surveillance supported by molecular approaches will be essential to provide a comprehensive picture of the impact of the vaccine on the burden reduction of pneumococcal meningitis and on pneumococcal serotype distribution.
Highlights
Meningitis epidemics in sub-Saharan Africa have been due to Neisseria meningitidis (Nm) serogroup A, responsible for the majority of the disease burden and accounting for several thousand cases every year
The introduction of the MenAfriVacTM vaccine in Burkina Faso, Mali and Niger has already contributed to a substantial decline in the number of meningitis cases due to meningococci irrespective of the ability of currently circulating serogroups W [4] and X [5] to lead to small-scale epidemics
Meningitis surveillance in Niger is undertaken by the Direction of Surveillance and Response to Epidemics (DSRE), Ministry of Public Health (MoPH)
Summary
Meningitis epidemics in sub-Saharan Africa have been due to Neisseria meningitidis (Nm) serogroup A, responsible for the majority of the disease burden and accounting for several thousand cases every year. Recurrent PM epidemics, mainly due to serotype 1 strains, have been observed in Burkina Faso and Togo from 2006 [3], mirroring the seasonality of meningococcal meningitis. The introduction of the MenAfriVacTM vaccine (conjugate vaccine against serogroup A meningococci) in Burkina Faso, Mali and Niger has already contributed to a substantial decline in the number of meningitis cases due to meningococci irrespective of the ability of currently circulating serogroups W [4] and X [5] to lead to small-scale epidemics. The decline of meningococcal meningitis next to the MenAfriVacTM campaign was concomitant to the rise PM cases, mainly in Burkina Faso. In order to ensure an effective vaccination strategy and post-vaccination surveillance, we examined the serotype distribution patterns of pneumococcal meningitis in Niger over the period 2003–2011
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