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Outbreaks of serogroup X meningococcal meningitis in Niger 1995-2000

S Djibo1, P Nicolas, J-M Alonso

  • 1CERMES, Niamey, Niger. sdjibo@cermes.ne

Tropical Medicine & International Health : TM & IH
|December 3, 2003
PubMed

Insights

Meningitis serogroup X caused 134 cases in Niamey between 1995-2000. These cases showed no clinical differences from serogroup A meningitis and occurred mainly during the dry season.

Area of Science:

  • Epidemiology
  • Infectious Diseases
  • Microbiology

Background:

  • Recurrent meningococcal meningitis epidemics in Africa are typically caused by serogroup A.
  • Other serogroups, like X and W135, have emerged causing sporadic cases or clusters.
  • Neisseria meningitidis serogroup X has been detected in the African meningitis belt.

Purpose of the Study:

  • To report and characterize meningitis cases caused by Neisseria meningitidis serogroup X in Niamey.
  • To compare the clinical and epidemiological features of serogroup X meningitis with serogroup A meningitis.
  • To analyze the incidence and seasonality of serogroup X meningitis.

Main Methods:

  • Meningitis cases were identified through Niger's routine surveillance system for reportable diseases.
  • Neisseria meningitidis strains were isolated and serogrouped by the CERMES reference laboratory in Niamey.
  • Further typing of isolates was performed at WHO collaborating centers in Marseille and Institut Pasteur, Paris.

Main Results:

  • 134 cases of meningitis due to Neisseria meningitidis serogroup X were reported in Niamey between 1995 and 2000.
  • Serogroup X represented 3.91% of meningococcal isolates, compared to 94.4% for serogroup A.
  • Cases due to serogroup X showed no clinical or epidemiological differences from serogroup A, with 93.3% occurring in the dry season.
  • The mean age of patients was 9.2 years, the M/F sex ratio was 1.3, and the case fatality rate was 11.9%.

Conclusions:

  • Neisseria meningitidis serogroup X caused a significant number of meningitis cases in Niamey during the study period.
  • Serogroup X meningitis shares clinical and epidemiological characteristics with serogroup A meningitis.
  • The incidence of serogroup X meningitis appeared cyclic and independent of serogroups A and C.

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