A Narrative Review of the W, X, Y, E, and NG of Meningococcal Disease: Emerging Capsular Groups, Pathotypes, and Global Control

Abstract

Neisseria meningitidis, carried in the human nasopharynx asymptomatically by ~10% of the population, remains a leading cause of meningitis and rapidly fatal sepsis, usually in otherwise healthy individuals. The epidemiology of invasive meningococcal disease (IMD) varies substantially by geography and over time and is now influenced by meningococcal vaccines and in 2020–2021 by COVID-19 pandemic containment measures. While 12 capsular groups, defined by capsular polysaccharide structures, can be expressed by N. meningitidis, groups A, B, and C historically caused most IMD. However, the use of mono-, bi-, and quadrivalent-polysaccharide-conjugate vaccines, the introduction of protein-based vaccines for group B, natural disease fluctuations, new drugs (e.g., eculizumab) that increase meningococcal susceptibility, changing transmission dynamics and meningococcal evolution are impacting the incidence of the capsular groups causing IMD. While the ability to spread and cause illness vary considerably, capsular groups W, X, and Y now cause significant IMD. In addition, group E and nongroupable meningococci have appeared as a cause of invasive disease, and a nongroupable N. meningitidis pathotype of the hypervirulent clonal complex 11 is causing sexually transmitted urethritis cases and outbreaks. Carriage and IMD of the previously “minor” N. meningitidis are reviewed and the need for polyvalent meningococcal vaccines emphasized.

Toward Establishing Integrated, Comprehensive, and Sustainable Meningitis Surveillance in Africa to Better Inform Vaccination Strategies

“…Currently available polyvalent meningococcal vaccines (comprising serogroups A, C, Y, and W) are not affordable, and their use in Africa has been restricted to reactive vaccination campaigns [ 19 ]. A pentavalent meningococcal conjugate vaccine targeting serogroups A, C, Y, W, and X is in the pipeline; however, data from surveillance systems are needed to guide vaccine strategy and implementation once the vaccine becomes available [ 20 ].…”

Clinical and Laboratory Findings of 12 Children with Invasive Meningococcal Disease in Pediatric Intensive Care Unit

“…Invasive meningococcal disease (IMD) due to Neisseria meningitidis is an important cause of morbidity and mortality in children worldwide [ 1 ]. N. meningitides are classified into 12 serogroups according to the antigenic variability of their capsules, and among them, serogroups A, B, C, Y, W, and X are clinically important [ 1 , 2 ]. The epidemiology of serogroups changes over the years, and patient data on clinical presentation and laboratory workup will be helpful for diagnosis and treatment [ 1 , 2 ].…”

“…N. meningitides are classified into 12 serogroups according to the antigenic variability of their capsules, and among them, serogroups A, B, C, Y, W, and X are clinically important [ 1 , 2 ]. The epidemiology of serogroups changes over the years, and patient data on clinical presentation and laboratory workup will be helpful for diagnosis and treatment [ 1 , 2 ]. A majority of the patients are below five years of age, and secondary peaks have been reported among adolescents and young adults [ 3 ].…”

“…A majority of the patients are below five years of age, and secondary peaks have been reported among adolescents and young adults [ 3 ]. While there are some risk factors associated with IMD, for example, travel to endemic regions, complement deficiency, splenectomy, HIV infection, or eculizumab use, the majority of the patients (>95%) with IMD were previously healthy [ 1 , 2 , 4 ].…”

Editorial for the Special Issue: Bacterial Meningitis—Epidemiology and Vaccination

“…Such models are relevant both for the serogroup A vaccine currently being deployed in the meningitis belt and for the anticipated roll out of pentavalent (ACWXY) conjugate vaccines [ 6 ]. The need for broader-valency vaccines in the global control of invasive meningococcal disease was well demonstrated in the paper by Tzeng and Stephens [ 9 ], describing the changing epidemiology and emerging disease due to serogroups other than A, B, and C.…”