Emerg Infect DiseidEmerging Infectious Diseases1080-60401080-6059Centers for Disease Control117476982631866Research ArticleClonal expansion of sequence type (ST-)5 and emergence of ST-7 in serogroup A meningococci, Africa.NicolasP.DécoussetL.RigletV.CastelliP.StorR.BlanchetG.Institut de Médecine Tropicale du Service de Santé des Armées, World Organization Collaborating Center, Marseille Armées, France. imtssa.meningo.free.frSep-Oct200175849854

One hundred four serogroup A meningococci in our collection, isolated in Africa from 1988 to 1999, were characterized by multilocus sequence typing (MLST). Our results and data from the Internet indicate that sequence type 5 (ST-5) strains were responsible for most of African outbreaks and sporadic cases during this period. In 1995, a new clone, characterized by ST-7 sequence, emerged and was responsible for severe outbreaks in Chad (1998) and Sudan (1999). MLST and epidemiologic data indicate that ST-5 and ST-7 represent two virulent clones. These two STs, which belong to subgroup III, differ only in the pgm locus: allele pgm3 is characteristic for ST-5 and allele pgm19 for ST-7. Subgroup III strains were responsible for two pandemics in the 1960s and 1980s. Our data show that the third subgroup III pandemic has now reached Africa.