Serogroup-Specific Characteristics of Localized Meningococcal Meningitis Epidemics in Niger 2002-2012 and 2015: Analysis of Health Center Level Surveillance Data.

Halima Boubacar Maïnassara,Jean-François Jusot,Juliette Paireau,Judith E Mueller,Arnaud Fontanet,Issa Idi,Odile Ouwe Missi Oukem-Boyer,Jean-Paul Moulia Pelat

doi:10.1371/journal.pone.0163110

Abstract

To compare dynamics of localized meningitis epidemics (LE) by meningococcal (Nm) serogroup, we analyzed a surveillance database of suspected and laboratory-confirmed Nm cases from 373 health areas (HA) of three regions in Niger during 2002–2012 and one region concerned by NmC epidemics during 2015. We defined LE as HA weekly incidence rates of ≥20 suspected cases per 100,000 during ≥2 weeks and assigned the predominant serogroup based on polymerase chain reaction testing of cerebrospinal fluid. Among the 175 LE, median peak weekly incidence rate in LE due to NmA, W, X and C were 54, 39, 109 and 46 per 100,000, respectively. These differences impacted ability of the epidemic to be detected at the district level. While this analysis is limited by the small number of LE due to NmX (N = 4) and NmW (N = 5), further research should explore whether strategies for prevention and response to meningitis epidemics need to be adapted according to predominant meningococcal serogroups.

Highlights

In the African meningitis belt, major epidemics of bacterial meningitis were historically due to the meningococcus of serogroup A
Spatial autocorrelation, while during other years, localized meningitis epidemics (LE) of any serogroup followed a random spatial pattern. In this description of serogroup-specific dynamics of meningitis epidemics at fine spatial scale in Niger, we found differences in peak epidemic force and cumulative annual incidence between serogroups
We found that epidemics due to NmX tended to have higher peak force at health center level than those due to serogroup A, while the peak force of NmW appeared to be lower

Summary

Introduction

In the African meningitis belt, major epidemics of bacterial meningitis were historically due to the meningococcus of serogroup A. Since the introduction of the conjugate vaccine against this predominant epidemic agent, (PsA-TT, MenAfrivac1), the overall incidence of suspected cases of acute bacterial meningitis has declined in all vaccinated countries and meningococcal (Nm) serogroup A cases have been identified only exceptionally [1]. Characteristics of Localized Meningococcal Meningitis Epidemics in Niger. Technique Belge” funded the first health area map’s support

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