Epidemiologic pattern of meningococcal meningitis in northern Cameroon in 2007-2010: contribution of PCR-enhanced surveillance

Abstract

Objectives: Monitoring acute bacterial meningitis in northern Cameroon.

Methods: Health professionals collected cerebrospinal fluid (CSF) specimens from patients presenting with clinical symptoms of meningitis. Specimens were tested using gram stain, latex agglutination test, and culture. A PCR assay completed the diagnostic testing. Multilocus sequence typing (MLST) was performed on some Neisseria meningitidis (Nm) isolates.

Results: From 2007 through 2010, of the 1429 CSF specimens tested, 292 (20·4%) were positive, either for Nm (205), Streptococcus pneumoniae (Sp) (57), or Haemophilus influenzae (Hi) (30). From 2007 through 2009, the serogroup W135 represented 98·8% of 164 case isolates. Until 2008, most serogroup W135 isolates presented the sequence-type ST-2881 usually associated with sporadic cases. Since 2009, the ST-11 (an epidemic-associated clone) became predominant, although no epidemic occurred. Serogroup A ST-7 was observed in 2010 and caused a localized epidemic. Using the detection PCR on turbid CSF, a 2·7-fold increase in cases with etiologic diagnosis was obtained, compared to culture. All tested meningococcal isolates (42) were susceptible to ampicillin, chloramphenicol, and cefotaxim.

Conclusions: Resurgence of serogroup A and recent increase in ST-11 among serogroup W135 isolates were worrying when considered with the epidemic wave of serogroup A meningitis, which affected neighboring countries and the serogroup W135 epidemic in Niger in 2009-2010.

Figure 1

Monthly distribution of cerebrospinal fluid (CSF) specimens tested at Centre Pasteur laboratory in Garoua and results, January 2007–December 2010. Red bars: Neisseria Meningitidis A (NmA); blue bars: Neisseria meningitidis (Nm) W135; yellow bars: Haemophilus Influenzae (Hi); green bars: Streptococcus Pneumoniae (Sp); black bars: turbid CSF without diagnosis; white bars: clear CSF without diagnosis.

Figure 2

Map of Cameroon with results of cerebrospinal fluid examined from 2007 to 2010.