Serogroup W meningococcal disease: global spread and current affect on the Southern Cone in Latin America

Abstract

Meningococcal serogroup W strains have been emerging throughout the current century with most of the isolates belonging to the sequence type (ST11)/electrophoretic type (ET37) clonal complex (ST11/E37 CC), particularly since the international outbreak following Hajj 2000. That outbreak appears to have triggered off that trend, contributing to the spread of W ST11/ET37 CC strains globally; however, local strains could be also responsible for increases in the percentage and/or incidence rates of this serogroup in some countries. More recently, unexpected increases in the percentage and incidence rate of W has been noticed in different countries located in the South Cone in Latin America, and W ST11/ET37 CC strains now appear as endemic in the region and an extensive immunization programme with tetravalent conjugate vaccine (covering serogroups A, C, Y and W) has been recently implemented in Chile. It is difficult to ascertain whether we are observing the emergence of W ST11 CC strains in different geographical areas or whether the Hajj 2000 strain is still spreading globally. Several aspects of the evolution of that situation are analysed in this paper, reviewing also the implications in immunization programmes. Closely related with the analysis of this potential evolution, it will be very interesting to monitor the evolution of serogroup W in the African meningitis belt after implementation of the extensive immunization programme with serogroup A conjugate vaccine that is currently underway. More data about carriers, transmission, clonal lineages, etc. are needed for taking decisions (target groups, outbreak control, defining the extent, etc.) to adapt the response strategy with potential interventions with broad coverage vaccines against the emergent serogroup W.

The Global Meningococcal Initiative: global epidemiology, the impact of vaccines on meningococcal disease and the importance of herd protection

“…In Chile, for example, the MenW incidence rate had risen to >0.5/100,000 by 2014, compared with <0.1/100,000 in 2010 (data from the ISPCH, Laboratorio de Agentes de Meningitis Bacteriana, Santiago, Chile); by 2012, 58% of MD was MenW [89]. The MenW ST-11/ET37 cc now appears to be endemic in the Southern Cone region [90]. In the United Kingdom, MenW has also been increasing; the new isolates belong to the ST-11/ET-37 complex but, again, appear to be different from the Hajj strain, although close to the South American isolates [35].…”

Increase in Meningococcal Serogroup W Disease, Victoria, Australia, 2013–2015

“…Neisseria meningitidis serogroup W (MenW) disease was believed to have little epidemic potential before the first international outbreak in 2000, which was related to the Hajj, and has subsequently been described in the African meningitis belt, South Africa, and Saudi Arabia ( 1 ). This serogroup emerged in the South Cone of South America in the mid-2000s and in the United Kingdom in 2009–2010.…”

“…This serogroup emerged in the South Cone of South America in the mid-2000s and in the United Kingdom in 2009–2010. Strains belonging to sequence type (ST) 11 are the most prevalent; those from the South Cone of South America are part of ST11 but have diversified ( 1 , 2 ). …”

[Meningococcal meningitis: a case of serogroup W in an underage migrant]

“…Un aumento inaspettato di casi dovuti al sierogruppo W è stato osservato anche in diverse regioni del Cono Sud nell'America Latina [21]. pseudotinea amiantacea (con campione negativo per la ricerca di miceti dermatofiti), che veniva trattata con soluzione topica di rifamicina e shampoo antibatterico.…”

“…Infatti, sia in Europa sia, in scala più ampia, a livello mondiale, emergono casi singoli o focolai attribuibili a sierogruppi diversi da quelli endemici, considerati propri di una determinata area geografica. Questo può avvenire per propagazione di casi da nuovi focolai (di cui gli eventi di mass gathering possono essere fattori favorenti) [14,21,22] o anche in seguito a interventi di prevenzione e sanità pubblica, come ad esempio l'introduzione di vaccinazioni di massa contro un dato sierogruppo, con la conseguente emergenza di altri ceppi [15][16][17]. L' epidemiologia del meningococco cambia e, anche in corrispondenza della Meningitis Belt, sembra che il sierogruppo W si stia affermando in maniera concreta, come suggeriscono i casi verificatisi e gli studi sulla sierotipizzazione nei portatori.…”