The 1998 Senegal epidemic of meningitis was due to the clonal expansion ofA : 4 : P1.9, clone III-I, sequence type 5 Neisseria meningitidis strains

Between January and April 1998, a meningitis outbreak due to serogroup A me ningococcus took place in Senegal, The outbreak began in Gandiaye, 165 Irm to the east of Dakar, and progressed towards the towns of Gossas, Niakkhar, Guinguineo, Fatik, Foundiougne, Dioffior, Sokone, Kaolack and Nioro. At th e same time, the outbreak reached regions of Kaffrine, Koungheul, and Tamba counda in the east of Senegal. A total of 1,350 cases and 200 deaths were r eported. The WHO Collaborating Center in Marseilles received 24 strains for analysis. All were serogroup A Neisseria meningitidis, type 1 and subtype P1.9. Multilocus enzyme electrophoresis, performed by Institut Pasteur Pari s, showed that the strains belonged to clone III-I. DNA restriction fragmen ts generated by endonuclease Bg/II and analyzed by pulsed-field gel electro phoresis showed 24 indistinguishable fingerprint patterns similar to those of meningococcus strains isolated from African outbreaks since 1988. Three strains were studied by multilocus sequence typing (MLST) with seven loci. The comparison between sequences and existing alleles on the MLST website ( http://mlst.zao.ox.ac.uk) allowed us to assign these strains to sequence ty pe 5 (ST5), as their sequences were identical to the consensus at seven loc i. All 24 strains were susceptible to penicillin, amoxicillin, chlorampheni col, and rifampin. Subgroup IU, is finishing its spread towards west of the meningitis belt of Africa. To our knowledge, this is the first time subgro up III, and more precisely ST5, strains are reported as being responsible f or a meningitis outbreak in Senegal.