Outbreaks of serogroup X meningococcal meningitis in Niger 1995–2000

Abstract

SummaryIn the African meningitis belt, the recurrent meningococcal meningitis epidemics are generally caused by serogroup A. In the past 20 years, other serogroups have been detected, such as X or W135, which have caused sporadic cases or clusters. We report here 134 meningitis cases caused by Neisseria meningitidis serogroup X that occurred in Niamey between 1995 and 2000. They represented 3.91% of the meningococcal isolates from all CSF samples, whereas 94.4% were of serogroup A. Meningococcal meningitis cases were detected using the framework of the routine surveillance system for reportable diseases organized by the Ministry of Public Health of Niger. The strains were isolated and determined by the reference laboratory for meningitis in Niamey (CERMES) and further typed at the WHO collaborating center of the Pharo in Marseille and at the National Reference Center for the Meningococci at the Institut Pasteur. Reference laboratories in Marseille and Paris characterized 47 isolates having the antigenic formula (serogroup:serotype:sero-subtype) X:NT:P1.5. Meningitis cases due to meningococcus serogroup X did not present any clinical or epidemiological differences to those due to serogroup A. The seasonal incidence was classical; 93.3% of the cases were recorded during the dry season. The mean age of patients was 9.2 years (±6 years). The sex ratio M/F was 1.3. Case fatality rate was 11.9% without any difference related to age or sex. The increasing incidence of the serogroup X was not related to the decrease of serogroup A, but seemed cyclic, and evolved independently of the recurrence of both serogroups A and C.

Biological diagnosis of meningococcal meningitis in the African meningitis belt: Current epidemic strategy and new perspectives

“…Bearing in mind these risks it is also important, therefore, to evaluate the performance of the new RDTs on blood and/or urine samples. In addition, a rapid test including diagnosis of NmX is now a priority for countries within the meningitis belt, as the threat of a recurrence of an outbreak due to this serogroup is currently possible [5,7].…”

“…Large epidemics are attributed predominantly to Neisseria meningitidis (Nm) serogroup A [3,4]. However serogroups C and X meningococci have been isolated during some epidemics [5][6][7] and, more of concern, serogroup W135 (NmW135) was identified in 2002-2003 as the main pathogen during outbreaks in Burkina Faso [8]. This serogroup is responsible for sporadic cases in many countries [9].…”

Development of a glycoconjugate vaccine to prevent meningitis in Africa caused by meningococcal serogroup X

“…In 2011, MenX accounted for 59% of confirmed cases of meningococcal meningitis in this country (7). Higher case fatality rates have been reported for meningitis caused by MenX compared with MenA (4,6), and children aged 1-9 y constitute the most affected age group (4,8).…”

<i>Neisseria meningitis</i> serogroup X outbreak in Burkina Faso, 2009-2010

“…Niger is moreover a West African country which had described the greatest number of meningitis serogroup X cases, with the first cases isolated in 1982 [23]. Then after a silent of 8 years, 22 cases were described in 1990 [12,24]. Between 1995 and 2000, serogroup X meningitis cases were annually detected, with a peak of 83 cases in 1997 [12,25,26].…”

“…But eight years after, this extension didn't occur and cases of meningitis W135 were relatively rarely identified in Burkina through national reinforced surveillance data system. Sporadic cases of meningitis caused by serogroupe X of Neisseria meningitis (NmX) were already reported in Niger in 1990 [10,11] and from 1995 to 2000 [12] and in Ghana in 2000 [13]. Since 2006, sporadic cases of NmX were also reported in some health Districts of Burkina Faso (Data from routine surveillance of Health Ministry not published).…”