Outbreak of W135 meningococcal disease in 2000: not emergence of a new W135 strain but clonal expansion within the electophoretic type-37 complex

Range of Clinical Manifestations Caused by Invasive Meningococcal Disease Due to Serogroup W: A Systematic Review

INTRODUCTION

Invasive meningococcal disease (IMD) due to serogroup W meningococci (MenW) is consistently reported with atypical clinical manifestations, including gastrointestinal symptoms, bacteremic pneumonia, and septic arthritis. We undertook a systematic review of the literature for a comprehensive assessment of the clinical presentation of IMD caused by MenW.

METHODS

PubMed and Embase databases were searched from inception to June 2022 using a combination of MeSH terms and free text for articles that reported symptoms and signs of MenW IMD, and associated manifestations.

RESULTS

The most commonly reported symptoms identified included: fever (range 36-100% of cases), nausea and/or vomiting (range 38-47%), vomiting (range 14-68%), cough (range 7-57%), sore throat (range 13-34%), headache (range 7-50%), diarrhea (range 8-47%), altered consciousness/mental status (range 7-38%), stiff neck (range 7-54%), and nausea (range 7-20%). Sepsis (range 15-83% of cases) was the most commonly reported manifestation followed by meningitis (range 5-72%), sepsis and meningitis (range 6-74%), bacteremic pneumonia (range 4-24%), arthritis (range 1-15%), and other manifestations (e.g., pharyngitis/epiglottitis/supraglottitis/tonsillitis/conjunctivitis; range 1-24%). The case fatality rates ranged from 8-40%, and among the survivors 4-14% had long-term sequelae.

CONCLUSIONS

Clinicians need to be aware of the nonspecific symptoms and signs of IMD, as well as of the atypical manifestations in regions where MenW is known to circulate to ensure timely diagnoses and treatment.

Epidemiology, clinical features and outcome of adults with meningococcal meningitis: a 15-year prospective nationwide cohort study

Background

We describe the epidemiology, clinical features and outcome of adult meningococcal meningitis in the Netherlands over a 15-year period.

Methods

We studied adults (age ≥ 16 years) who were listed by the Netherlands Reference Laboratory for Bacterial Meningitis and/or included in the prospective nationwide cohort study (MeninGene) between January 2006 and July 2021. Incidences were calculated per epidemiological year (July-June).

Findings

We identified 442 episodes of adult meningococcal meningitis. The median patient age was 32 years (IQR 18-55) and 226 episodes (51%) occurred in female patients. The annual incidence per 100,000 adults fluctuated, from 0.33 in 2006-2007 to 0.05 in 2020-2021, with a temporal increase up to 0.30 from 2016 to 2018, driven by an outbreak of serogroup W (MenW). Of 442 episodes, 274 episodes (62%) in 273 patients were included in the clinical cohort study. The overall case fatality rate was 4% (10 of 274) and 16% (43 of 274) had an unfavourable outcome (Glasgow Outcome Scale score 1-4). Compared to other serogroups, MenW was associated with higher rates of unfavourable outcome (6 of 16 [38%] vs. 37 of 251 [15%], P = 0.03) and death (4 of 16 [25%] vs. 6 of 251 [2%], P = 0.001).

Interpretation

The overall incidence of adult meningococcal meningitis in the Netherlands is low and outcome is generally favourable. An increase of MenW meningitis occurred from 2016 to 2018, which was associated with more unfavourable outcome and death.

Funding

Netherlands Organisation for Health Research and Development, European Research Council, National Institute of Public Health and Environmental protection.

Trends in Neisseria meningitidis serogroups amongst patients with suspected cerebrospinal meningitis in the meningitis belt of Ghana: a 5-year retrospective study

BACKGROUND

Serogroup A Neisseria meningitidis was the major cause of meningococcal meningitis epidemics in the African meningitis belt before 2010 when the monovalent meningococcal A conjugate vaccine (MenAfriVac) was introduced in the region. Therefore, this study aimed to establish the trends in N. meningitidis serogroups from 2016 to 2020 in Ghana's meningitis belt.

METHODS

Polymerase chain reaction (PCR) confirmed laboratory results of suspected cases of cerebrospinal meningitis from January, 2016 to March, 2020 were obtained from the Tamale Public Health Laboratory. The data were subjected to trend analysis using Statistical Package for the Social Sciences version 25. Differences between discrete variables were analyzed using the Cochran-Armitage trend test.

RESULTS

Of the 2,426 suspected cases, 395 (16.3%) were confirmed positive for N. meningitidis using PCR. Serogroup X showed a significant upward trend (P < 0.01), and serogroup W showed a downward trend (P < 0.01). However, no significant trend was observed for any other serogroup.

CONCLUSION

This study showed the emergence of serogroup X, a non-vaccine type, as the predominant N. meningitidis serogroup in the wake of a declining serogroup W in Ghana's meningitis belt.

Identification of the nasopharyngeal carriage of Neisseria meningitidis by 16S rRNA Gene sequencing in asymptomatic adolescents and young adults in Cartagena, Colombia (2019–2020)

The bacterium Neisseria meningitidis, a strictly human pathogen, can cause meningitis, meningococcemia, sepsis, and death; repeatedly it scause outbreaks around the world. The frequency of asymptomatic carriage is often high in adolescents and young adults, increasing the invasive meningococcal disease risk and likelihood of transmission. However, detailed analyses of meningococcal carriage in this population in Colombia, particularly in coastal areas, are lacking. In this study, the prevalence and characteristics of Neisseria meningitidis carriage were evaluated in asymptomatic adolescents and young adults (11-25 years old) in Cartagena, Colombia. Oropharynx samples were collected from participants between August and December 2019. The phenotypic identification of bacteria was performed by conventional methods and biochemical testing. Molecular identification to the species level was performed by 16S rRNA gene sequencing. In total, 12 of 648 samples were positive for Neisseria meningitidis by 16S rRNA sequencing, indicating a prevalence of 1.9%. Isolates were classified into four invasive serogroups (A, B, C, and W) by a comparative sequence analysis of the ribosomal gene. Despite the occurrence of meningococcal disease in Cartagena city in the last several years, the frequency of oropharyngeal carriage in adolescents and young adults was low. Serogroup A had not been previously reported in nasopharyngeal samples in Colombia. This is the first report of Neisseria meningitidis on the Colombian Caribbean coast based on 16S rRNA sequencing and is expected to guide the development of vaccination and follow-up strategies.

Genomic surveillance of Neisseria meningitidis serogroup W in Portugal from 2003 to 2019

In recent years, a change in the epidemiology of meningococcal disease caused by Neisseria meningitidis serogroup W (MenW) has been observed worldwide, with the emergence of new sublineages associated with a higher rate of fatal cases. The present study intends to describe the epidemiology of invasive meningococcal disease (IMD) due to MenW in Portugal between 2003 and 2019, and to genetically characterize population structure. Despite MenW has a low incidence in Portugal, having almost disappeared from 2008 to 2015, since 2016, the number of MenW cases has been steadily increasing at a rate of ~ twofold per year, with more than 80% of the characterized isolates belonging to clonal complex 11 (cc11). Core-genome phylogeny of 25 Portuguese (PT) MenW isolates showed a strain clustering mainly either with the Original UK or the UK 2013 sublineages. Our study also reported for the first time the presence of distinct prophages with a notable overrepresentation of an ~ 32-35-kb PS_1-like prophage found in MenW cc11 genomes. The presence of the PS_1-like prophage in almost all 4723 cc11 genomes selected from Neisseria PubMLST database regardless of the capsular group they belong to suggests an ancestral acquisition of this mobile element prior to capsular switching events. Overall, by mimicking the scenario observed worldwide, this study reinforces the importance of a close monitoring of MenW disease, especially from cc11, in order to promptly adapt the vaccination plan for IMD control in Portugal. Moreover, future studies are needed to understand the putative contribution of prophages to fitness and virulence of PT MenW strains.

Deciphering the role of nanoparticles for management of bacterial meningitis: an update on recent studies

Meningitis is an inflammation of the protective membranes called meninges and fluid adjacent the brain and spinal cord. The inflammatory progression expands all through subarachnoid space of the brain and spinal cord and occupies the ventricles. The pathogens like bacteria, fungi, viruses, or parasites are main sources of infection causing meningitis. Bacterial meningitis is a life-threatening health problem that which needs instantaneous apprehension and treatment. Nesseria meningitidis, Streptococcus pneumoniae, and Haemophilus flu are major widespread factors causing bacterial meningitis. The conventional drug delivery approaches encounter difficulty in crossing this blood-brain barrier (BBB) and therefore are insufficient to elicit the desired pharmacological effect as required for treatment of meningitis. Therefore, application of nanoparticle-based drug delivery systems has become imperative for successful dealing with this deadly disease. The nanoparticles have ability to across BBB via four important transport mechanisms, i.e., paracellular transport, transcellular (transcytosis), endocytosis (adsorptive transcytosis), and receptor-mediated transcytosis. In this review, we reminisce distinctive symptoms of meningitis, and provide an overview of various types of bacterial meningitis, with a focus on its epidemiology, pathogenesis, and pathophysiology. This review describes conventional therapeutic approaches for treatment of meningitis and the problems encountered by them while transmitting across tight junctions of BBB. The nanotechnology approaches like functionalized polymeric nanoparticles, solid lipid nanoparticles, nanostructured lipid carrier, nanoemulsion, liposomes, transferosomes, and carbon nanotubes which have been recently evaluated for treatment or detection of bacterial meningitis have been focused. This review has also briefly summarized the recent patents and clinical status of therapeutic modalities for meningitis.

Evolution of Sequence Type 4821 Clonal Complex Hyperinvasive and Quinolone-Resistant Meningococci

Expansion of quinolone-resistant Neisseria meningitidis clone China^{CC4821-R1-C/B} from sequence type (ST) 4821 clonal complex (CC4821) caused a serogroup shift from serogroup A to serogroup C invasive meningococcal disease (IMD) in China. To determine the relationship among globally distributed CC4821 meningococci, we analyzed whole-genome sequence data from 173 CC4821 meningococci isolated from 4 continents during 1972–2019. These meningococci clustered into 4 sublineages (1–4); sublineage 1 primarily comprised of IMD isolates (41/50, 82%). Most isolates from outside China (40/49, 81.6%) formed a distinct sublineage, the Europe–USA cluster, with the typical strain designation B:P1.17-6,23:F3-36:ST-3200(CC4821), harboring mutations in penicillin-binding protein 2. These data show that the quinolone-resistant clone China^{CC4821-R1-C/B} has expanded to other countries. The increasing distribution worldwide of serogroup B CC4821 raises the concern that CC4821 has the potential to cause a pandemic that would be challenging to control, despite indirect evidence that the Trumenba vaccine might afford some protection.

Carbohydrate based meningococcal vaccines: past and present overview

Neisseria meningitidis is a major cause of bacterial meningitidis worldwide. Children less than five years and adolescents are particularly affected. Nearly all invasive strains are surrounded by a polysaccharide capsule, based on which, 12 N. meningitidis serogroups are differentiated. Six of them, A, B, C, W, X, and Y, cause the vast majority of infections in humans. Mono- and multi-valent carbohydrate-based vaccines against meningococcal infections have been licensed or are currently in clinical development. In this mini-review, an overview of the past and present approaches for producing meningococcal glycoconjugate vaccines is provided.

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

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.

A Review of the Epidemiology of Invasive Meningococcal Disease and Vaccination Strategies in North Africa

OBJECTIVE

This narrative review considers the epidemiology of invasive meningococcal disease (IMD) in North Africa and the adequacy of current preventive measures to provide guidance for future vaccination strategies.

METHODS

Literature searches were conducted using PubMed for articles published from 1998 onwards to identify publications on IMD in North Africa. Additional relevant articles not included within the search results and data sources were identified from the reference lists of identified publications, authors' personal files, and publicly available government or regional surveillance data.

RESULTS

Although IMD is an endemic and notifiable disease in several North African countries, inadequacies exist regarding each country's surveillance, vaccination strategies, and disease understanding. Studies showed bacterial meningitis in North Africa caused by Neisseria meningitidis mostly affects young children (aged <5 years), with meningococcal serogroup B (MenB) being the most frequently identified serotype. Importantly, MenB isolates were genetically heterogeneous. Serogroup A incidence and meningococcal outbreaks decreased over time in Morocco and Egypt, possibly because of their nationwide or school-based vaccination programs. Within the region, meningococcal vaccines are only included in the national immunization program of Egypt.

CONCLUSIONS

Improving IMD diagnosis and surveillance would provide a reliable estimate of IMD burden, leading to better vaccination strategies.

Cocirculation of Hajj and non-Hajj strains among serogroup W meningococci in Italy, 2000 to 2016

In Italy, B and C are the predominant serogroups among meningococci causing invasive diseases. Nevertheless, in the period from 2013 to 2016, an increase in serogroup W Neisseria meningitidis (MenW) was observed. This study intends to define the main characteristics of 63 MenW isolates responsible of invasive meningococcal disease (IMD) in Italy from 2000 to 2016. We performed whole genome sequencing on bacterial isolates or single gene sequencing on culture-negative samples to evaluate molecular heterogeneity. Our main finding was the cocirculation of the Hajj and the South American sublineages belonging to MenW/clonal complex (cc)11, which gradually surpassed the MenW/cc22 in Italy. All MenW/cc11 isolates were fully susceptible to cefotaxime, ceftriaxone, ciprofloxacin, penicillin G and rifampicin. We identified the full-length NadA protein variant 2/3, present in all the MenW/cc11. We also identified the fHbp variant 1, which we found exclusively in the MenW/cc11/Hajj sublineage. Concern about the epidemic potential of MenW/cc11 has increased worldwide since the year 2000. Continued surveillance, supported by genomic characterisation, allows high-resolution tracking of pathogen dissemination and the detection of epidemic-associated strains.

Suspected cluster of Neisseria meningitidis W invasive disease in an elderly care home: do new laboratory methods aid public health action? United Kingdom, 2015

In 2015, a suspected cluster of two invasive meningococcal disease (IMD) cases of serogroup W Neisseria meningitidis (MenW) occurred in elderly care home residents in England over 7 months; case investigations followed United Kingdom guidance. An incident control team reviewed epidemiological information. Phenotyping of case specimens informed public health action, including vaccination and throat swabs to assess carriage. Whole genome sequencing (WGS) was conducted on case and carrier isolates. Conventional phenotyping did not exclude a microbiological link between cases (case 1 W:2a:P1.5,2 and case 2 W:2a:NT). After the second case, 33/40 residents and 13/32 staff were vaccinated and 19/40 residents and 13/32 staff submitted throat swabs. Two MenW carriers and two MenC carriers were detected. WGS showed that MenW case and carrier isolates were closely related and possibly constituted a locally circulating strain. Meningococcal carriage, transmission dynamics and influence of care settings on IMD in older adults are poorly understood. WGS analyses performed following public health action helped to confirm the close relatedness of the case and circulating isolates despite phenotypic differences and supported actions taken. WGS was not sufficiently timely to guide public health practice.

Characterization of invasive Neisseria meningitidis isolates recovered from children in Turkey during a period of increased serogroup B disease, 2013-2017

Diverse Neisseria meningitidis strains belonging to various serogroups and clonal complexes cause epidemic and endemic life-threatening disease worldwide. This study aimed to investigate the genetic diversity of recent invasive meningococci in Turkey with respect to multilocus sequence type (MLST) and also meningococcal serogroup B (MenB) vaccine antigens to enable assessment of potential MenB strain coverage using the genetic Meningococcal Antigen Typing System (gMATS). Fifty-four isolates, representing 37.5% of all pediatric (ages 0-18 years) invasive meningococcal disease cases in Turkey from January 2013 to December 2017, underwent genome sequence analysis. Thirty-six (66.7%) isolates were MenB, 10 (18.5%) were serogroup W (MenW), 4 (7.4%) were serogroup A (MenA), 3 (5.6%) were serogroup Y (MenY) and 1 (1.8%) was serogroup X (MenX). The MenB isolates were diverse with cc35 (19.4%), cc41/44 (19.4%) and cc32 (13.8%) as the most prevalent clonal complexes. The MenW isolates (n = 10) comprised cc11 (n = 5), ST-2754 (cc-unassigned; n = 4) and cc22 (n = 1). gMATS was indicative of high 4CMenB coverage (72.2-79.1%) of Turkish invasive MenB strains from pediatric patients. Strain coverage of several clonal complexes differed from that seen elsewhere in Europe highlighting the importance of performing local assessments and also the use of phenotypic methods, i.e. MATS, where possible. All of the isolates possessed in-frame fhbp alleles and so were potentially covered by MenB-fHbp. Continued surveillance is essential to guide recommendations for current and future vaccines as well as understanding changes in epidemiology.

Neisseria meningitidis: using genomics to understand diversity, evolution and pathogenesis

Meningococcal disease remains an important cause of morbidity and death worldwide despite the development and increasing implementation of effective vaccines. Elimination of the disease is hampered by the enormous diversity and antigenic variability of the causative agent, Neisseria meningitidis, one of the most variable bacteria in nature. These features are attained mainly through high rates of horizontal gene transfer and alteration of protein expression through phase variation. The recent availability of whole-genome sequencing (WGS) of large-scale collections of N. meningitidis isolates from various origins, databases to facilitate storage and sharing of WGS data and the concomitant development of effective bioinformatics tools have led to a much more thorough understanding of the diversity of the species, its evolution and population structure and how virulent traits may emerge. Implementation of WGS is already contributing to enhanced epidemiological surveillance and is essential to ascertain the impact of vaccination strategies. This Review summarizes the recent advances provided by WGS studies in our understanding of the biology of N. meningitidis and the epidemiology of meningococcal disease.

The Hajj 2019 Vaccine Requirements and Possible New Challenges

Each year millions of pilgrims perform the annual Hajj from more than 180 countries around the world. This is one of the largest mass gathering events and may result in the occurrence and spread of infectious diseases. As such, there are mandatory vaccinations for the pilgrims such as meningococcal vaccines. The 2019 annual Hajj will take place during August 8-13, 2019. Thus, we review the recommended and mandated vaccinations for the 2019 Hajj and Umrah. The mandatory vaccines required to secure the visa include the quadrivalent meningococcal vaccine for all pilgrims, while yellow fever, and poliomyelitis vaccines are required for pilgrims coming from countries endemic or with disease activity. The recommended vaccines are influenza, pneumococcal, in addition to full compliance with basic vaccines for all pilgrims against diphtheria, tetanus, pertussis, polio, measles, and mumps. It is imperative to continue surveillance for the spread of antimicrobial resistance and occurrence of all infectious diseases causing outbreaks across the globe in the last year, like Zika virus, MDR-Typhoid, Nipah, Ebola, cholera, chikungunya and Middle East Respiratory Syndrome Coronavirus.

Comparative genomic analyses of Chinese serogroup W ST-11 complex Neisseria meningitidis isolates

Although serogroup W ST-11 complex (cc11) (W:cc11) Neisseria meningitidis has been widespread in China over the past ten years, its origin and genetic relatedness has not yet been described. In this study, we described the genetic relatedness and discuss the possible origin of Chinese W:cc11 isolates by comparing their genome sequences with those of other cc11 strains globally. Comparative genomic analysis with geo-temporally diverse cc11 isolates showed that the Chinese W:cc11 isolates exclusively formed two closely related subclusters within a distinct sublineage (proposed as the Chinese-strain sublineage) of lineage 11.1 close to the interface between the Hajj-strain sublineage and the South American-strain sublineage. Several isolates from Africa and Europe were closely related to the Chinese subclusters which were largely segregated from one another among distinct provinces of China. No alleles were identified that were unique to the Chinese isolates as a whole, though each subcluster possessed unique alleles differentiating itself from the other subcluster as well as closely related isolates within the extended sublineage. Three genes differentiated the two subclusters with allele combinations that were each present among the non-Chinese isolates within the wider sublineage. These results indicate that the Chinese W:cc11 isolates formed part of a previously undescribed W:cc11 sublineage that is closely related to, but distinct from, the Hajj-strain sublineage and South American-strain sublineage. The geographical source of the Chinese subclusters was indeterminate based on available data.

Global estimate of Neisseria meningitidis serogroups proportion in invasive meningococcal disease: A systematic review and meta-analysis

Using the PRISMA guideline, 102 studies were included in this study. The highest and the lowest proportion of N. meningitidis serogroups in invasive meningococcal disease (IMD) was for NmB with 48.5% (95% CI: 45-52) and NmX with 0.7% (95% CI: 0.3-1.7). Among the WHO regional offices, serogroup NmW with 57.5% (95% CI: 35-77.5) in Eastern Mediterranean, and NmZ with 0.1% (95% CI: 0-0.9) in America had the highest and the lowest proportion of N. meningitidis serogroups in IMD. NmC with 9.7% (95% CI: 5.6-16.2) and NmB with 9.5% (95% CI: 0.2-3.8) had the highest proportion in 1-4 and <1 year age groups, respectively. Our analysis showed that NmB had the highest proportion of N. meningitidis serogroups in IMD worldwide. However, proportion of N. meningitidis serogroups in IMD varied noticeably across countries and age groups. Therefore, establishing appropriate control guidelines depending on the geographical regions and age groups is essential for prevention of IMD.

Management of meningococcal outbreaks: are we using the same language? Comparison of the public health policies between high-income countries with low incidence of meningococcal disease

BACKGROUND

Invasive meningococcal disease (IMD) in high-income countries usually occurs sporadically with low incidence and occasionally as small clusters or outbreaks. The WHO guidelines (GLs) for IMD outbreak applies only to African countries with high endemic incidence. Several high-income countries developed their own GLs on IMD outbreak, and we compare their terminology, classification, definitions, and public health interventions.

METHODS

National IMD outbreak GLs of the European Union and the Organisation for Economic Co-operation and Development member states were compared. Due to linguistic barriers, 17 out of forty-one countries were selected, and the GLs on the websites of the national health authorities were independently screened by two researchers.

RESULTS

National GLs on IMD outbreak were available for 12 countries. All GLs classify IMD outbreak into organization and community based using different terminology (cluster, epidemic, etc.). Two GLs introduce also a third condition of hyperendemic. Definitions, thresholds, and countermeasures vary among countries.

CONCLUSIONS

Different definitions of organization and community-based outbreaks and countermeasures are expected because of uncertainties about their effectiveness, and differences between countries in health-care systems and public health policy approaches. Nevertheless, variations in terminology, definitions and countermeasures are confusing and reflect the need for an international standardization.

The Impact of Nucleotide Sequence Analysis on Meningococcal Vaccine Development and Assessment

Since it became available as a routine tool in biology, the determination and analysis of nucleotide sequences has been applied to the design of vaccines and the investigation of their effectiveness. As vaccination is primarily concerned with the interaction of biological molecules with the immune system, the utility of sequence data is not immediately obvious and, indeed, nucleotide sequence data are most effective when used to complement more conventional immunological approaches. Here, the impact of sequencing on the field of vaccinology will be illustrated with reference to the development and implementation of vaccines against Neisseria meningitidis (the meningococcus) over the 30-year period from the late-1980s to the late-2010s. Nucleotide sequence-based studies have been important in the fight against this aggressive pathogen largely because of its high genetic and antigenic diversity, properties that were only fully appreciated because of sequence-based studies. Five aspects will be considered, the use of sequence data to: (i) discover vaccine antigens; (ii) assess the diversity and distribution of vaccine antigens; (iii) determine the evolutionary and population biology of the organism and their implications for immunization; and (iv) develop molecular approaches to investigate pre- and post-vaccine pathogen populations to assess vaccine impact. One of the great advantages of nucleotide sequence data has been its scalability, which has meant that increasingly large data sets have been available, which has proved invaluable in the investigation of an organism as diverse and enigmatic as the meningococcus.

Whole genome sequencing of Neisseria meningitidis W isolates from the Czech Republic recovered in 1984-2017

Introduction

The study presents the analysis of whole genome sequence (WGS) data for Neisseria meningitidis serogroup W isolates recovered in the Czech Republic in 1984–2017 and their comparison with WGS data from other countries.

Material and methods

Thirty-one Czech N. meningitidis W isolates, 22 from invasive meningococcal disease (IMD) and nine from healthy carriers were analysed. The 33-year study period was divided into three periods: 1984–1999, 2000–2009, and 2010–2017.

Results

Most study isolates from IMD and healthy carriers were assigned to clonal complex cc22 (n = 10) in all study periods. The second leading clonal complex was cc865 (n = 8) presented by IMD (n = 7) and carriage (n = 1) isolates that emerged in the last study period, 2010–2017. The third clonal complex was cc11 (n = 4) including IMD isolates from the first (1984–1999) and third (2010–2017) study periods. The following clonal complex was cc174 (n = 3) presented by IMD isolates from the first two study periods, i.e. 1984–1999 and 2000–2009. One isolate of each cc41/44 and cc1136 originated from healthy carriers from the second study period, 2000–2009. The comparison of WGS data for N. meningitidis W isolates recovered in the Czech Republic in the study period 1984–2017 and for isolates from other countries recovered in the same period showed that clonal complex cc865, ST-3342 is unique to the Czech Republic since 2010. Moreover, the comparison shows that cc11 in the Czech Republic does not comprise novel hypervirulent lineages reported from both European and non-European countries. All 31 study isolates were assigned to Bexsero® Antigen Sequence Types (BAST), and seven of them were of newly described BASTs.

Conclusions

WGS analysis contributed considerably to a more detailed molecular characterization of N. meningitidis W isolates recovered in the Czech Republic over a 33-year period and allowed for a spatial and temporal comparison of these characteristics between isolates from the Czech Republic and other countries. The most interesting finding of this study is that eight of 31 Czech isolates of N. meningitidis W belong to clonal complex cc865, which is uncommon for serogroup W. In addition, the WGS data precised the base for the update of the recommendation for vaccination in the Czech Republic.

Whole-Genome Sequencing of Emerging Invasive Neisseria meningitidis Serogroup W in Sweden

Invasive disease caused by Neisseria meningitidis serogroup W (MenW) has historically had a low incidence in Sweden, with an average incidence of 0.03 case/100,000 population from 1995 to 2014. In recent years, a significant increase in the incidence of MenW has been noted in Sweden, to an average incidence of 0.15 case/100,000 population in 2015 to 2016. In 2017 (1 January to 30 June), 33% of invasive meningococcal disease cases (7/21 cases) were caused by MenW. In the present study, all invasive MenW isolates from Sweden collected in 1995 to June 2017 (n = 86) were subjected to whole-genome sequencing to determine the population structure and to compare isolates from Sweden with historical and international cases. The increase of MenW in Sweden was determined to be due to isolates belonging to the South American sublineage of MenW clonal complex 11, namely, the novel U.K. 2013 lineage. This lineage was introduced in Sweden in 2013 and has since been the dominant lineage of MenW.

A cluster of invasive meningococcal disease (IMD) caused by Neisseria meningitidis serogroup W among university students, France, February to May 2017

Between February and May 2017, two cases of invasive meningococcal disease caused by a new, rapidly expanding serogroup W meningococci variant were reported among students of an international university in Paris. Bacteriological investigations showed that isolates shared identical genotypic formula (W:P1.5,2:F1-1:cc11) and belonged to the South American/UK lineage. A vaccination campaign was organised that aimed at preventing new cases linked to potential persistence of the circulation of the bacteria in the students.

Expected immunizations and health protection for Hajj and Umrah 2018 -An overview

BACKGROUND

The annual Hajj and Umrah are one of the largest recurring religious mass gatherings across the globe drawing pilgrims from more than 185 countries. The living circumstances and activities of the pilgrims may create an environment for the occurrence and spread of communicable diseases. Each year, the Health authority of the Kingdom of Saudi Arabia, in coordination with international health authorities, updates health requirements for pilgrims. The Hajj for 2017 took place from August 24 to September 5, 2017. Here, we review the expected obligations for immunizations for the 2018 Hajj and Umrah.

RESULTS

The Hajj and Umrah vaccine requirements include mandatory vaccinations against yellow fever, quadrivalent meningococcal polysaccharide (every 3 years) or conjugated (every 5 years) vaccines and poliomyelitis vaccine. Influenza vaccine utilizing the 2016 (Southern Hemisphere vaccine to all pilgrims) was recommended but was not obligatory for pilgrims. Ciprofloxacin is required for individuals >12 years excluding pregnant women as chemoprophylaxis to be given at the port of entry for Pilgrims coming from the meningitis belt. With the ongoing outbreaks of measles in Europe, it is recommended that all pilgrims have an updated immunization against vaccine-preventable diseases (diphtheria, tetanus, pertussis, polio, measles and mumps).

CONCLUSION

The mandatory vaccines remain the same with continued vigilance for the development of any new or emerging infectious diseases. Continuing surveillance for Zika virus, cholera and MERS-CoV are ongoing.

Multiple Sources of Genetic Diversity of Influenza A Viruses during the Hajj

Outbreaks of respiratory virus infection at mass gatherings pose significant health risks to attendees, host communities, and ultimately the global population if they help facilitate viral emergence. However, little is known about the genetic diversity, evolution, and patterns of viral transmission during mass gatherings, particularly how much diversity is generated by in situ transmission compared to that imported from other locations. Here, we describe the genome-scale evolution of influenza A viruses sampled from the Hajj pilgrimages at Makkah during 2013 to 2015. Phylogenetic analysis revealed that the diversity of influenza viruses at the Hajj pilgrimages was shaped by multiple introduction events, comprising multiple cocirculating lineages in each year, including those that have circulated in the Middle East and those whose origins likely lie on different continents. At the scale of individual hosts, the majority of minor variants resulted from de novo mutation, with only limited evidence of minor variant transmission or minor variants circulating at subconsensus level despite the likely identification of multiple transmission clusters. Together, these data highlight the complexity of influenza virus infection at the Hajj pilgrimages, reflecting a mix of global genetic diversity drawn from multiple sources combined with local transmission, and reemphasize the need for vigilant surveillance at mass gatherings.IMPORTANCE Large population sizes and densities at mass gatherings such as the Hajj (Makkah, Saudi Arabia) can contribute to outbreaks of respiratory virus infection by providing local hot spots for transmission followed by spread to other localities. Using a genome-scale analysis, we show that the genetic diversity of influenza A viruses at the Hajj gatherings during 2013 to 2015 was largely shaped by the introduction of multiple viruses from diverse geographic regions, including the Middle East, with only little evidence of interhost virus transmission at the Hajj and seemingly limited spread of subconsensus mutational variants. The diversity of viruses at the Hajj pilgrimages highlights the potential for lineage cocirculation during mass gatherings, in turn fuelling segment reassortment and the emergence of novel variants, such that the continued surveillance of respiratory pathogens at mass gatherings should be a public health priority.

An international invasive meningococcal disease outbreak due to a novel and rapidly expanding serogroup W strain, Scotland and Sweden, July to August 2015

The 23rd World Scout Jamboree in 2015 took place in Japan and included over 33,000 scouts from 162 countries. Within nine days of the meeting ending, six cases of laboratory-confirmed invasive serogroup W meningococcal disease occurred among scouts and their close contacts in Scotland and Sweden. The isolates responsible were identical to one-another by routine typing and, where known (4 isolates), belonged to the ST-11 clonal complex (cc11) which is associated with large outbreaks and high case fatality rates. Recent studies have demonstrated the need for high-resolution genomic typing schemes to assign serogroup W cc11 isolates to several distinct strains circulating globally over the past two decades. Here we used such schemes to confirm that the Jamboree-associated cases constituted a genuine outbreak and that this was due to a novel and rapidly expanding strain descended from the strain that has recently expanded in South America and the United Kingdom. We also identify the genetic differences that define the novel strain including four point mutations and three putative recombination events involving the horizontal exchange of 17, six and two genes, respectively. Noteworthy outcomes of these changes were antigenic shifts and the disruption of a transcriptional regulator.

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

Background

In Ontario, serogroup W Neisseria meningitidis (MenW) accounts for a small percentage of all invasive meningococcal disease (IMD) and between 2010 and 2014, only zero to three confirmed cases occurred per year. However, between August 2015 and June 2016, six culture confirmed MenW IMD cases were reported in Ontario.

Objective

All MenW IMD cases in Ontario between January 1, 2009 and June 30, 2016 were reviewed and the N. meningitidis strains involved were characterized.

Methods

MenW cases were identified in the Integrated Public Health Information System byf Public Health Ontario. MenW isolates were characterized at the National Microbiology Laboratory.

Results

Of the thirteen MenW IMD cases, six were due to isolates typed as sequence type (ST)-22 clonal complex (cc), six were of ST-11 cc, and one ST-167 cc. Most (83%) MenW cases due to the ST-22 cc occurred prior to 2012 while all six MenW cases due to ST-11 cc happened since May 2014. The six MenW ST-11 isolates appeared to be clonal.

Conclusion

It appears that a genetic shift in the invasive MenW isolates has occurred in Ontario in 2014 with the ST-11 clone replacing the traditional ST-22 clone.

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

INTRODUCTION

The 2015 Global Meningococcal Initiative (GMI) meeting discussed the global importance of meningococcal disease (MD) and its continually changing epidemiology. Areas covered: Although recent vaccination programs have been successful in reducing incidence in many countries (e.g. Neisseria meningitidis serogroup [Men]C in Brazil, MenA in the African meningitis belt), new clones have emerged, causing outbreaks (e.g. MenW in South America, MenC in Nigeria and Niger). The importance of herd protection was highlighted, emphasizing the need for high vaccination uptake among those with the highest carriage rates, as was the need for boosters to maintain individual and herd protection following decline of immune response after primary immunization. Expert commentary: The GMI Global Recommendations for Meningococcal Disease were updated to include a recommendation to enable access to whole-genome sequencing as for surveillance, guidance on strain typing to guide use of subcapsular vaccines, and recognition of the importance of advocacy and awareness campaigns.

The Establishment and Diversification of Epidemic-Associated Serogroup W Meningococcus in the African Meningitis Belt, 1994 to 2012

Epidemics of invasive meningococcal disease (IMD) caused by meningococcal serogroup A have been eliminated from the sub-Saharan African so-called "meningitis belt" by the meningococcal A conjugate vaccine (MACV), and yet, other serogroups continue to cause epidemics. Neisseria meningitidis serogroup W remains a major cause of disease in the region, with most isolates belonging to clonal complex 11 (CC11). Here, the genetic variation within and between epidemic-associated strains was assessed by sequencing the genomes of 92 N. meningitidis serogroup W isolates collected between 1994 and 2012 from both sporadic and epidemic IMD cases, 85 being from selected meningitis belt countries. The sequenced isolates belonged to either CC175 (n = 9) or CC11 (n = 83). The CC11 N. meningitidis serogroup W isolates belonged to a single lineage comprising four major phylogenetic subclades. Separate CC11 N. meningitidis serogroup W subclades were associated with the 2002 and 2012 Burkina Faso epidemics. The subclade associated with the 2012 epidemic included isolates found in Burkina Faso and Mali during 2011 and 2012, which descended from a strain very similar to the Hajj (Islamic pilgrimage to Mecca)-related Saudi Arabian outbreak strain from 2000. The phylogeny of isolates from 2012 reflected their geographic origin within Burkina Faso, with isolates from the Malian border region being closely related to the isolates from Mali. Evidence of ongoing evolution, international transmission, and strain replacement stresses the importance of maintaining N. meningitidis surveillance in Africa following the MACV implementation. IMPORTANCE Meningococcal disease (meningitis and bloodstream infections) threatens millions of people across the meningitis belt of sub-Saharan Africa. A vaccine introduced in 2010 protects against Africa's then-most common cause of meningococcal disease, N. meningitidis serogroup A. However, other serogroups continue to cause epidemics in the region-including serogroup W. The rapid identification of strains that have been associated with prior outbreaks can improve the assessment of outbreak risk and enable timely preparation of public health responses, including vaccination. Phylogenetic analysis of newly sequenced serogroup W strains isolated from 1994 to 2012 identified two groups of strains linked to large epidemics in Burkina Faso, one being descended from a strain that caused an outbreak during the Hajj pilgrimage in 2000. We find that applying whole-genome sequencing to meningococcal disease surveillance collections improves the discrimination among strains, even within a single nation-wide epidemic, which can be used to better understand pathogen spread.

The Changing Epidemiology of Meningococcal Disease

The incidence of meningococcal disease is at an historic low in the United States, but prevention remains a priority because of the devastating outcomes and risk for outbreaks. Available vaccines are recommended routinely for persons at increased risk for disease to protect against all major serogroups of Neisseria meningitidis circulating in the United States. Although vaccination has virtually eliminated serogroup A meningococcal outbreaks from the Meningitis Belt of Africa and reduced the incidence of serogroup C disease worldwide, eradication of N meningitidis will unlikely be achieved by currently available vaccines because of the continued carriage and transmission of nonencapsulated organisms.

Infectious diseases epidemic threats and mass gatherings: refocusing global attention on the continuing spread of the Middle East Respiratory syndrome coronavirus (MERS-CoV)

Media and World Health Organization (WHO) attention on Zika virus transmission at the 2016 Rio Olympic Games and the 2015 Ebola virus outbreak in West Africa diverted the attention of global public health authorities from other lethal infectious diseases with epidemic potential. Mass gatherings such as the annual Hajj pilgrimage hosted by Kingdom of Saudi Arabia attract huge crowds from all continents, creating high-risk conditions for the rapid global spread of infectious diseases. The highly lethal Middle Eastern respiratory syndrome coronavirus (MERS-CoV) remains in the WHO list of top emerging diseases likely to cause major epidemics. The 2015 MERS-CoV outbreak in South Korea, in which 184 MERS cases including 33 deaths occurred in 2 months, that was imported from the Middle East by a South Korean businessman was a wake-up call for the global community to refocus attention on MERS-CoV and other emerging and re-emerging infectious diseases with epidemic potential. The international donor community and Middle Eastern countries should make available resources for, and make a serious commitment to, taking forward a "One Health" global network for proactive surveillance, rapid detection, and prevention of MERS-CoV and other epidemic infectious diseases threats.

Meningococcal disease during the Hajj and Umrah mass gatherings

The Hajj and Umrah religious mass gatherings hosted by the Kingdom of Saudi Arabia can facilitate the transmission of infectious diseases. The pilgrimages have been associated with a number of local and international outbreaks of meningococcal disease. These include serogroup A disease outbreaks in 1987 and throughout the 1990s and two international serogroup W135 outbreaks in 2000 and 2001. The implementation of strict preventative measures including mandatory quadrivalent meningococcal vaccination and antibiotic chemoprophylaxis for pilgrims from the African meningitis belt has prevented pilgrimage-associated meningococcal outbreaks since 2001. However, the fluid epidemiology of the disease and the possibility of outbreaks caused by serogroups not covered by the vaccine or emerging hyper-virulent strains, mean that the disease remains a serious public health threat during these events. Continuous surveillance of carriage state and the epidemiology of the disease in the Kingdom and globally and the introduction of preventative measures that provide broad and long-lasting immunity and impact carriage are warranted.

Global epidemiology of capsular group W meningococcal disease (1970-2015): Multifocal emergence and persistence of hypervirulent sequence type (ST)-11 clonal complex

Following an outbreak in Mecca Saudi Arabia in 2000, meningococcal strains expressing capsular group W (W) emerged as a major cause of invasive meningococcal disease (IMD) worldwide. The Saudi Arabian outbreak strain (Hajj clone) belonging to the ST-11 clonal complex (cc11) is similar to W cc11 causing occasional sporadic disease before 2000. Since 2000, W cc11 has caused large meningococcal disease epidemics in the African meningitis belt and endemic disease in South America, Europe and China. Traditional molecular epidemiologic typing suggested that a majority of current W cc11 burden represented global spread of the Hajj clone. However, recent whole genome sequencing (WGS) analyses revealed significant genetic heterogeneity among global W cc11 strains. While continued spread of the Hajj clone occurs in the Middle East, the meningitis belt and South Africa have co-circulation of the Hajj clone and other unrelated W cc11 strains. Notably, South America, the UK, and France share a genetically distinct W cc11 strain. Other W lineages persist in low numbers in Europe, North America and the meningitis belt. In summary, WGS is helping to unravel the complex genomic epidemiology of group W meningococcal strains. Wider application of WGS and strengthening of global IMD surveillance is necessary to monitor the continued evolution of group W lineages.

Prevention of meningococcal disease during the Hajj and Umrah mass gatherings: past and current measures and future prospects

The Kingdom of Saudi Arabia (KSA) has a long history of instituting preventative measures against meningococcal disease (MD). KSA is at risk of outbreaks of MD due to its geographic location, demography, and especially because it hosts the annual Hajj and Umrah mass gatherings. Preventative measures for Hajj and Umrah include vaccination, targeted chemoprophylaxis, health awareness and educational campaigns, as well as an active disease surveillance and response system. Preventative measures have been introduced and updated in accordance with changes in the epidemiology of MD and available preventative tools. The mandatory meningococcal vaccination policy for pilgrims has possibly been the major factor in preventing outbreaks during the pilgrimages. The policy of chemoprophylaxis for all pilgrims arriving from the African meningitis belt has also probably been important in reducing the carriage and transmission of Neisseria meningitidis in KSA and beyond. The preventative measures for Hajj and Umrah are likely to continue to focus on vaccination, but to favour the conjugate vaccine for its extra benefits over the polysaccharide vaccines. Additionally, the surveillance system will continue to be strengthened to ensure early detection and response to cases and outbreaks; ongoing disease awareness campaigns for pilgrims will continue, as will chemoprophylaxis for target groups. Local and worldwide surveillance of the disease and drug-resistant N. meningitidis are crucial in informing future recommendations for vaccination, chemoprophylaxis, and treatment. Preventative measures should be reviewed regularly and updated accordingly, and compliance with these measures should be monitored and enhanced to prevent MD during Hajj and Umrah, as well as local and international outbreaks.

Tick-borne Rickettsiales: Molecular tools for the study of an emergent group of pathogens

The use of molecular techniques in recent years has enhanced the sensitivity and specificity of the diagnosis of Rickettsiales, a bacterial order which includes significant emerging and re-emerging pathogens of humans and animals. Molecular detection enables the accurate identification at the species level, providing additional information on the epidemiology and course of the clinical cases. Moreover, PCR and enzyme restriction analysis of the vector blood meal can be employed to study the tick feeding source and possibly identify pathogen's reservoir. Here, we review the molecular tools available for the identification and characterization of tick-borne bacteria from the genera Rickettsia, Ehrlichia and Anaplasma and for the study of ticks feeding behavior. We summarize the significant criteria for taxonomic identification of Rickettsiales species and propose a procedure algorithm for the classification of bacterial isolates as members of this order.

Genomic Epidemiology of Hypervirulent Serogroup W, ST-11 Neisseria meningitidis

Neisseria meningitidis is a leading bacterial cause of sepsis and meningitis globally with dynamic strain distribution over time. Beginning with an epidemic among Hajj pilgrims in 2000, serogroup W (W) sequence type (ST) 11 emerged as a leading cause of epidemic meningitis in the African ‘meningitis belt’ and endemic cases in South America, Europe, Middle East and China. Previous genotyping studies were unable to reliably discriminate sporadic W ST-11 strains in circulation since 1970 from the Hajj outbreak strain (Hajj clone). It is also unclear what proportion of more recent W ST-11 disease clusters are caused by direct descendants of the Hajj clone. Whole genome sequences of 270 meningococcal strains isolated from patients with invasive meningococcal disease globally from 1970 to 2013 were compared using whole genome phylogenetic and major antigen-encoding gene sequence analyses. We found that all W ST-11 strains were descendants of an ancestral strain that had undergone unique capsular switching events. The Hajj clone and its descendants were distinct from other W ST-11 strains in that they shared a common antigen gene profile and had undergone recombination involving virulence genes encoding factor H binding protein, nitric oxide reductase, and nitrite reductase. These data demonstrate that recent acquisition of a distinct antigen-encoding gene profile and variations in meningococcal virulence genes was associated with the emergence of the Hajj clone. Importantly, W ST-11 strains unrelated to the Hajj outbreak contribute a significant proportion of W ST-11 cases globally. This study helps illuminate genomic factors associated with meningococcal strain emergence and evolution.

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Genomic characterization of serogroup W ST-11 of Neisseria meningitidis.

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Epidemic W ST-11 strain (Hajj clone) emerged through recombination affecting virulence genes.

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Both the Hajj clone and W ST-11 strains unrelated to the Hajj outbreak have persisted globally.

Neisseria meningitidis, a bacterial cause of frequently fatal brain (meningitis) and blood stream (sepsis) infections, has variable strain distribution over time. Serogroup W sequence type 11 (W ST-11) lineage is associated on one hand with strains causing only rare (sporadic) disease cases, and the Hajj clone – a major global cause of epidemic and endemic meningococcal disease. In this study we analyzed complete genome sequences of a global collection of 270 W ST-11 isolates causing meningococcal disease from 1970-2013. The Hajj clone acquired novel gene sequences within genes involved in nitrogen metabolism (nitrogen oxide reductase, nitrite reductase) and evasion of human immune response (factor H binding protein). These genes may be the cause of increased virulence of the Hajj clone and can be used to trace continuing spread of the clone. These results shed light on mechanisms of meningococcal strain emergence.

Genomic resolution of an aggressive, widespread, diverse and expanding meningococcal serogroup B, C and W lineage

OBJECTIVES

Neisseria meningitidis is a leading cause of meningitis and septicaemia. The hyperinvasive ST-11 clonal complex (cc11) caused serogroup C (MenC) outbreaks in the US military in the 1960s and UK universities in the 1990s, a global Hajj-associated serogroup W (MenW) outbreak in 2000-2001, and subsequent MenW epidemics in sub-Saharan Africa. More recently, endemic MenW disease has expanded in South Africa, South America and the UK, and MenC cases have been reported among European and North American men who have sex with men (MSM). Routine typing schemes poorly resolve cc11 so we established the population structure at genomic resolution.

METHODS

Representatives of these episodes and other geo-temporally diverse cc11 meningococci (n = 750) were compared across 1546 core genes and visualised on phylogenetic networks.

RESULTS

MenW isolates were confined to a distal portion of one of two main lineages with MenB and MenC isolates interspersed elsewhere. An expanding South American/UK MenW strain was distinct from the 'Hajj outbreak' strain and a closely related endemic South African strain. Recent MenC isolates from MSM in France and the UK were closely related but distinct.

CONCLUSIONS

High resolution 'genomic' multilocus sequence typing is necessary to resolve and monitor the spread of diverse cc11 lineages globally.

Neisseria meningitidis serogroup W, Burkina Faso, 2012

In 2010, Burkina Faso became the first country to introduce meningococcal serogroup A conjugate vaccine (PsA-TT). During 2012, Burkina Faso reported increases in Neisseria meningitidis serogroup W, raising questions about whether these cases were a natural increase in disease or resulted from serogroup replacement after PsA-TT introduction. We analyzed national surveillance data to describe the epidemiology of serogroup W and genotyped 61 serogroup W isolates. In 2012, a total of 5,807 meningitis cases were reported through enhanced surveillance, of which 2,353 (41%) were laboratory confirmed. The predominant organism identified was N. meningitidis serogroup W (62%), and all serogroup W isolates characterized belonged to clonal complex 11. Although additional years of data are needed before we can understand the epidemiology of serogroup W after PsA–TT introduction, these data suggest that serogroup W will remain a major cause of sporadic disease and has epidemic potential, underscoring the need to maintain high-quality case-based meningitis surveillance after PsA–TT introduction.

Genetic diversity of Neisseria meningitidis serogroup C ST-4821 in China based on multiple-locus variable number tandem repeat analysis

Neisseria meningitidis sequence type (ST)-4821 was first reported in China in 2003, and a new hyper-virulent lineage has been designated as the ST-4821 complex. A large number of N. meningitidis ST-4821 strains have been identified in China since 2003; however, the microevolution characteristics of this complex are unclear. Different combinations of variable number of tandem repeats (VNTR) loci were used in multiple-locus VNTR analysis (MLVA) to analyze 118 N. meningitidis serogroup C ST-4821 strains isolated from seventeen provinces between 2003 and 2012. Additionally, MLVA with five VNTR loci was performed due to its high discriminatory power. One hundred and eighteen isolates were found to comprise 112 subtypes based on MLVA, and 16 outbreak-associated strains were clustered into one group. These data indicate a high level of diversity for N. meningitidis ST-4821 due to microevolution in the last decade. In addition, the results revealed high similarity between isolates from the same geographic origins, which is helpful when monitoring the spread of N. meningitidis serogroup C ST-4821 and will provide valuable information for the control and prevention of bacterial meningitis in China.

Clonal characteristics of invasive Neisseria meningitidis following initiation of an A + C vaccination program in China, 2005-2012

OBJECTIVES

To reveal the population structure of invasive Neisseria meningitidis isolates after the initiation of an A + C vaccination program in China.

METHODS

Multilocus sequence typing (MLST) and PorA typing were used to characterize 238 invasive N. meningitidis isolates collected in China between 2005 and 2012.

RESULTS

During this period, sequence type (ST)-5, ST-4821 and ST-11 complexes were dominant among serogroups A, C and W, accounting for 100%, 98.5% and 100% of each serogroup, respectively. P1.20,9, P1.7-2,14 and P1.5,2 were the dominant PorA types of serogroups A, C and W, respectively. Serogroup B showed high genetic diversity with two dominant lineages: ST-4821 complex and ST-5662 subgroup.

CONCLUSIONS

The population of 238 invasive N. meningitidis isolates was primarily composed of a select group of recognized hypervirulent lineages. Among these clonal complexes, ST-7 serogroup A and ST-11 serogroup W are distributed globally, and other three clones exist only in China.

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

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.

Neisseria adhesin A variation and revised nomenclature scheme

Neisseria adhesin A (NadA), involved in the adhesion and invasion of Neisseria meningitidis into host tissues, is one of the major components of Bexsero, a novel multicomponent vaccine licensed for protection against meningococcal serogroup B in Europe, Australia, and Canada. NadA has been identified in approximately 30% of clinical isolates and in a much lower proportion of carrier isolates. Three protein variants were originally identified in invasive meningococci and named NadA-1, NadA-2, and NadA-3, whereas most carrier isolates either lacked the gene or harbored a different variant, NadA-4. Further analysis of isolates belonging to the sequence type 213 (ST-213) clonal complex identified NadA-5, which was structurally similar to NadA-4, but more distantly related to NadA-1, -2, and -3. At the time of this writing, more than 89 distinct nadA allele sequences and 43 distinct peptides have been described. Here, we present a revised nomenclature system, taking into account the complete data set, which is compatible with previous classification schemes and is expandable. The main features of this new scheme include (i) the grouping of the previously named NadA-2 and NadA-3 variants into a single NadA-2/3 variant, (ii) the grouping of the previously assigned NadA-4 and NadA-5 variants into a single NadA-4/5 variant, (iii) the introduction of an additional variant (NadA-6), and (iv) the classification of the variants into two main groups, named groups I and II. To facilitate querying of the sequences and submission of new allele sequences, the nucleotide and amino acid sequences are available at http://pubmlst.org/neisseria/NadA/.