title: Epidemiological patterns of meningococcal meningitis in Niger in 2003 and 2004: under the threat of N. meningitidis serogroup W135.
abstract: Since the Neisseria meningitidis serogroup W135 epidemic in Burkina Faso in 2002, the neighbouring countries dread undergoing outbreaks. Niger has strongly enhanced the microbiological surveillance, especially by adding the polymerase chain reaction (PCR) assay to the national framework of the surveillance system. During the 2003 epidemic season, 8113 clinically suspected cases of meningitis were notified and nine districts of the 42 crossed the epidemic threshold, while during the 2004 season, the number of cases was 3521 and four districts notified epidemics. In 2003 and 2004, serogroup A was identified in most N. meningitidis from cerebrospinal fluid (CSF) specimens (89.7% of 759 and 87.2% of 406, respectively). Although serogroup W135 represented only 8.3% of the meningococcal meningitis in 2003 and 7.9% in 2004, and was not involved in outbreaks, it was widespread in various areas of the country. In the regions that notified epidemics, the proportion of serogroup W135 was tiny while it exceeded 40% in several non-epidemic regions. Despite the wide distribution of W135 serogroup in Niger and the fears expressed in 2001, the threat of a large epidemic caused by N. meningitidis W135 seems to have been averted in Niger so far. There is no clear indication whether this serogroup will play a lasting role in the epidemiology of meningococcal meningitis or not. As early as in the 1990s, a significant but transient increase in the incidence of N. meningitidis serogroup X was observed. Close microbiological surveillance is crucial for monitoring the threat and for identifying at the earliest the serogroups involved in epidemics.
authors.affiliation: CERMES, Réseau International des Instituts Pasteur, Ministère de la Santé, Niamey, Niger. pascal.boisier@cermes.ne
authors.forename: Pascal
authors.initials: P
authors.lastname: Boisier
authors.forename: Saacou
authors.initials: S
authors.lastname: Djibo
authors.forename: Fati
authors.initials: F
authors.lastname: Sidikou
authors.forename: Habsatou
authors.initials: H
authors.lastname: Mindadou
authors.forename: Kiari Kaka
authors.initials: KK
authors.lastname: Kairo
authors.forename: Ali
authors.initials: A
authors.lastname: Djibo
authors.forename: Kadade
authors.initials: K
authors.lastname: Goumbi
authors.forename: Suzanne
authors.initials: S
authors.lastname: Chanteau
mesh_terms: D000890:Anti-Infective Agents / Q000627:therapeutic use; D002648:Child; D004196:Disease Outbreaks; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008585:Meningitis, Meningococcal / Q000134:cerebrospinal fluid / Q000453:epidemiology* / Q000401:mortality; D038582:Neisseria meningitidis, Serogroup W-135 / Q000302:isolation & purification / Q000472:pathogenicity*; D009548:Niger / Q000453:epidemiology; D016133:Polymerase Chain Reaction / Q000379:methods; D011159:Population Surveillance / Q000379:methods; D012621:Seasons
chemical_list: D000890:Anti-Infective Agents