title: Outbreak of W135 meningococcal disease in 2000: not emergence of a new W135 strain but clonal expansion within the electophoretic type-37 complex.
abstract: In 2000, >400 cases of disease caused by Neisseria meningitidis serogroup W135 (MenW135), the largest MenW135 outbreak reported to date, occurred worldwide among Hajj pilgrims and their contacts. To elucidate the origin of the outbreak strains and to investigate their relatedness to major clonal groups, genotypic and phenotypic subtyping was performed on 26 MenW135 outbreak-associated isolates and 50 MenW135 isolates collected worldwide from 1970 through 2000. All outbreak-associated isolates were members of a single clone of the hypervirulent electrophoretic type (ET)-37 complex, designated the "(W)ET-37 clone"; 19 additional MenW135 strains were also members of this clone, and the remaining 31 MenW135 strains were clearly distinct. The 2000 MenW135 outbreak was not caused by emergence of a new MenW135 strain but rather by expansion of the (W)ET-37 clone that has been in circulation at least since 1970; the strains most closely related to those causing the 2000 outbreak have been isolated in Algeria, Mali, and The Gambia in the 1990s.
authors.affiliation: Meningitis and Special Pathogens, Division of Bacterial and Mycotic Diseases, National Center for Infectious Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road NE, Atlanta, GA 30333, USA. lmayer@cdc.gov
authors.forename: Leonard W
authors.initials: LW
authors.lastname: Mayer
authors.forename: Michael W
authors.initials: MW
authors.lastname: Reeves
authors.forename: Nasser
authors.initials: N
authors.lastname: Al-Hamdan
authors.forename: Claudio T
authors.initials: CT
authors.lastname: Sacchi
authors.forename: Muhamed-Kheir
authors.initials: MK
authors.lastname: Taha
authors.forename: Gloria W
authors.initials: GW
authors.lastname: Ajello
authors.forename: Susanna E
authors.initials: SE
authors.lastname: Schmink
authors.forename: Corie A
authors.initials: CA
authors.lastname: Noble
authors.forename: Maria Lucia C
authors.initials: ML
authors.lastname: Tondella
authors.forename: Anne M
authors.initials: AM
authors.lastname: Whitney
authors.forename: Yagoub
authors.initials: Y
authors.lastname: Al-Mazrou
authors.forename: Mohammed
authors.initials: M
authors.lastname: Al-Jefri
authors.forename: Amin
authors.initials: A
authors.lastname: Mishkhis
authors.forename: Sameer
authors.initials: S
authors.lastname: Sabban
authors.forename: Dominique A
authors.initials: DA
authors.lastname: Caugant
authors.forename: Jairam
authors.initials: J
authors.lastname: Lingappa
authors.forename: Nancy E
authors.initials: NE
authors.lastname: Rosenstein
authors.forename: Tanja
authors.initials: T
authors.lastname: Popovic
mesh_terms: D015373:Bacterial Typing Techniques; D004269:DNA, Bacterial / Q000032:analysis / Q000235:genetics; D004196:Disease Outbreaks; D004586:Electrophoresis / Q000379:methods; D005838:Genotype; D014943:Global Health; D006801:Humans; D007514:Islam; D008589:Meningococcal Infections / Q000453:epidemiology* / Q000382:microbiology; D009345:Neisseria meningitidis / Q000145:classification* / Q000235:genetics* / Q000502:physiology; D010641:Phenotype; D012336:RNA, Ribosomal, 16S / Q000235:genetics; D017422:Sequence Analysis, DNA / Q000379:methods; D014195:Travel; D014774:Virulence / Q000235:genetics
chemical_list: D004269:DNA, Bacterial; D012336:RNA, Ribosomal, 16S