Epidemiological changes in meningococcal meningitis in Niger from 2008 to 2011 and the impact of vaccination.

Jean-Marc Collard (1) , Bassira Issaka (1) , Maman Zaneidou (2) , Stéphane Hugonnet (3) , Pierre Nicolas (4) , Muhamed-Kheir Taha (5) , Brian Greenwood (6) , Jean-François Jusot (1)

1 CERMES - Centre de Recherche Médicale et Sanitaire (Niamey, Niger)
2 Direction de la Surveillance et de la Riposte aux Epidémies
3 OMS / WHO - Organisation Mondiale de la Santé / World Health Organization Office
4 WHO Collaborative Center for the meningococcus
5 CC-OMS - WHO-CC - Centre Collaborateur de l'OMS pour les méningites bactériennes - WHO Collaborating Center Bacterial Meningitis
6 LSHTM - London School of Hygiene and Tropical Medicine

BACKGROUND: The epidemiology of bacterial meningitis in the African 'meningitis belt' changes periodically. In order to design an effective vaccination strategy, we have examined the epidemiological and microbiological patterns of bacterial meningitis, and especially that of meningococcal meningitis, in Niger during the period 2008-2011. During this period a mass vaccination campaign with the newly developed meningococcal A conjugate vaccine (MenAfriVac(R)) was undertaken. METHOD: Cerebrospinal fluid samples were collected from health facilities throughout Niger and analysed by culture, seroagglutination and/or speciation polymerase chain reaction, followed by genogrouping PCR for of Neisseria meningitidis infections. A sample of strains were analysed by multi-locus sequence typing. RESULTS: N. meningitidis serogroup A cases were prevalent in 2008 and 2009 [98.6% and 97.5% of all N. meningitidis cases respectively]. The prevalence of serogroup A declined in 2010 [26.4%], with the emergence of serogroup W Sequence Type (ST) 11 [72.2% of cases], and the serogroup A meningococcus finally disappeared in 2011. The geographical distribution of cases N. meningitidis serogroups A and W within Niger is described. CONCLUSION: The substantial decline of serogroup A cases that has been observed from 2010 onwards in Niger seems to be due to several factors including a major polysaccharide A/C vaccination campaign in 2009, the introduction of MenAfriVac(R) in 10 districts at risk in December 2010, the natural dynamics of meningococcal infection and the persistence of serogroup A sequence-type 7 for about 10 years. The emergence of serogroup W strains suggests that there may be a need for serogroup W containing vaccines in Niger in the coming years.

Domaines: Maladies infectieuses

Jean-Marc Collard, Bassira Issaka, Maman Zaneidou, Stéphane Hugonnet, Pierre Nicolas, et al.. Epidemiological changes in meningococcal meningitis in Niger from 2008 to 2011 and the impact of vaccination.. BMC Infectious Diseases, 2013, 13 (1), pp.576. ⟨10.1186/1471-2334-13-576⟩. ⟨pasteur-00917555⟩