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.

Invasive serogroup W Neisseria meningitidis (MenW) in Ontario, Canada shows potential clonal replacement during the period January 1, 2009 – June 30, 2016

“…Prior to the spring of 2000, ST-11 MenW has only caused sporadic disease. However, the first large MenW outbreak involving >400 cases from 16 countries due to a ST-11 cc strain was reported among the pilgrims attending the Hajj in Mecca in year 2000 (13,14). Subsequent sporadic cases were thought to be due to pilgrims returning from the Hajj and transmitting the infection to their close contacts, as have been reported in Europe (15).…”

“…This clone seems to have emerged and displaced the traditional MenW clone of W:NT:P1.6 that belonged to the ST-22 cc since May 2014 (authors' unpublished data). Through genotypic and phenotypic analysis, ST-11 MenW 2a:P1.5,2 was first identified in Canada in 1970 (13). Prior to the spring of 2000, ST-11 MenW has only caused sporadic disease.…”

Vaccines based on the cell surface carbohydrates of pathogenic bacteria

“…Whilst Haemophilus influenzae disease is caused overwhelmingly by a single serotype, the type b, pneumococcal disease is caused by a very large number of the ninety known serotypes. Meningococcal disease in developed countries is principally Groups B and C, although Groups W135 and Y are becoming increasingly important, and Group A disease is virtually unknown (Racoosin et al 1998, Mayer et al 2002. Meningococcal Group A strains are, however, responsible for the regular meningitis epidemics which plague subSaharan Africa.…”

Enfermedad meningocóccica: siempre presente. Cambios en los serogrupos en el Cono Sur

“…Hay datos de aislamiento de estas cepas desde antes del año 2000, como lo demuestra el aislamiento en un paciente originario de Indonesia, retornado de la peregrinación en el año 1996 6 . Un probable "switch" capsular del serogrupo C al W135 ocurrió posiblemente desde la década del 70.…”

“…Mayer y cols. estudiaron cepas MenW135 provenientes de diversos países donde habían ocurrido los brotes relacionados con la peregrinación, mediante serotipificación y marcadores genéticos 6 . Todos los brotes asociados fueron producidos por el mismo clon hipervirulento, el ST-11/complejo ET-37 7 .…”