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

Abstract

BackgroundThe 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®) was undertaken.MethodCerebrospinal 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 Neisseria meningitidis infections. A sample of strains were analysed by multi-locus sequence typing.ResultsN. 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.ConclusionThe 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® 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.

Development and Evaluation of a Dipstick Diagnostic Test for Neisseria meningitidis Serogroup X

“…In addition, the test remained proficient (NPV, Ն0.95) if the prevalence increased to 50%. These considerations seem realistic and reflect the current epidemiological situation in the meningitis belt after the introduction of MenAfriVac, which was associated with a significant decrease in NmA (9). Indeed, this small-scale prospective use of the new RDT in the three centers located in this area (Abidjan, Garoua, and Niamey), suggests, on the basis of the sensitivities of RDT and PCR (which are Ͻ100%), that NmX may be present, albeit not as a dominating pathogen.…”

“…In the meningitis belt, N. meningitidis serogroup A (NmA) predominated prior to the introduction of the NmA polysaccharide-protein conjugate vaccine (MenAfriVac) (6), while other serogroups (mainly serogroups W [NmW] and X [NmX]), were also detected and still are. Of particular concern, outbreaks due to isolates of NmW and NmX were recently reported in Africa (7)(8)(9). Surveillance of the distribution of meningococcal serogroups is therefore important, and its comprehensiveness will benefit from diagnostic tools that can be widely used at the bedside.…”

Pathogens Penetrating the Central Nervous System: Infection Pathways and the Cellular and Molecular Mechanisms of Invasion

“…N. meningitidis is most likely to cause meningitis in children and adolescents and has a mortality rate of 10.1% in the United States (14). The serotypes most commonly implicated are A, B, C, W135, and Y (14,(36)(37)(38), and meningitis without shock is the most common presentation (38). The predominant clinical feature, which can distinguish N. meningitidis from other causes of bacterial meningitis, is the presence of a petechial rash.…”

Geophysical investigation of Obot Ekpo Landslide site, Cross River State, Nigeria

“…Rather, isolated communities in the country are usually challenged annually by recurring flood, erosion and storminduced hazards (George et al, 2008a,b;Akpan et al, 2009;Ezezika and Adetona, 2011;Okoyeh et al, 2013), in addition to the occasional outbreaks of epidemics such as yellow fever (Ezezika and Adetona, 2011), cholera (Adagbada et al, 2012; http://dx.doi.org/10.1016/j.jafrearsci.2015.05.015 1464-343X/Ó 2015 Elsevier Ltd. All rights reserved. Ogunniyi, 2014) and meningitis (Collard et al, 2013). Isolated low-magnitude earthquakes (tremors) have also occurred at different times (Akpan and Yakubu, 2010;Afegbua et al, 2011).…”