An epidemiological review of changes in meningococcal biology during the last 100 years

The genomic epidemiology of Neisseria meningitidis carriage from a randomised controlled trial of 4CMenB vaccination in an asymptomatic adolescent population

Background

Oropharyngeal carriage of Neisseria meningitidis is frequent during adolescence, representing a major source of invasive meningococcal disease. This study examined the impact of a serogroup B vaccination (Bexsero, GSK 4CMenB) programme on adolescent N. meningitidis carriage using genomic data.

Methods

A total 34,489 oropharyngeal samples were collected as part of a state-wide cluster randomised-controlled trial in South Australia during 2017 and 2018 (NCT03089086). Samples were screened for the presence of N. meningitidis DNA by porA PCR prior to culture. Whole genome sequencing was performed on all 1772 N. meningitidis culture isolates and their genomes were analysed.

Findings

Unencapsulated meningococci were predominant at baseline (36.3% of isolates), followed by MenB (31.0%), and MenY (20.5%). Most MenB were ST-6058 from hyperinvasive cc41/44, or ST-32 and ST-2870 from cc32. For MenY, ST-23 and ST-1655 from cc23 were prevalent. Meningococcal carriage was mostly unchanged due to the vaccination programme; however, a significant reduction in ST-53 capsule-null meningococci prevalence was observed in 2018 compared to 2017 (OR = 0.52; 95% CI: 0.30-0.87, p = 0.0106). This effect was larger in the vaccinated compared to the control group (OR = 0.37; 95% CI: 0.12-0.98, p = 0.0368).

Interpretation

While deployment of the 4CMenB vaccination did not alter the carriage of hyperinvasive MenB in the vaccinated population, it altered the carriage of other N. meningitidis sequence types following the vaccination program. Our findings suggest 4CMenB vaccination is unlikely to reduce transmission of hyperinvasive N. meningitidis strains and therefore ongoing targeted vaccination is likely a more effective public health intervention.

Funding

This work was funded by GlaxoSmithKline Biologicals SA.

The important lessons lurking in the history of meningococcal epidemiology

INTRODUCTION

The epidemiology of invasive meningococcal disease (IMD), a rare but potentially fatal illness, is typically described as unpredictable and subject to sporadic outbreaks.

AREAS COVERED

Meningococcal epidemiology and vaccine use during the last ~ 200 years are examined within the context of meningococcal characterization and classification to guide future IMD prevention efforts.

EXPERT OPINION

Historical and contemporary data highlight the dynamic nature of meningococcal epidemiology, with continued emergence of hyperinvasive clones and affected regions. Recent shifts include global increases in serogroup W disease, meningococcal antimicrobial resistance (AMR), and meningococcal urethritis; additionally, unvaccinated populations have experienced disease resurgences following lifting of COVID-19 restrictions. Despite these changes, a close analysis of meningococcal epidemiology indicates consistent dominance of serogroups A, B, C, W, and Y and elevated IMD rates among infants and young children, adolescents/young adults, and older adults. Demonstrably effective vaccines against all 5 major disease-causing serogroups are available, and their prophylactic use represents a powerful weapon against IMD, including AMR. The World Health Organization's goal of defeating meningitis by the year 2030 demands broad protection against IMD, which in turn indicates an urgent need to expand meningococcal vaccination programs across major disease-causing serogroups and age-related risk groups.

Cytokines in the Brain and Neuroinflammation: We Didn’t Starve the Fire!

In spite of the brain-protecting tissues of the skull, meninges, and blood-brain barrier, some forms of injury to or infection of the CNS can give rise to cerebral cytokine production and action and result in drastic changes in brain function and behavior. Interestingly, peripheral infection-induced systemic inflammation can also be accompanied by increased cerebral cytokine production. Furthermore, it has been recently proposed that some forms of psychological stress may have similar CNS effects. Different conditions of cerebral cytokine production and action will be reviewed here against the background of neuroinflammation. Within this context, it is important to both deepen our understanding along already taken paths as well as to explore new ways in which neural functioning can be modified by cytokines. This, in turn, should enable us to put forward different modes of cerebral cytokine production and action in relation to distinct forms of neuroinflammation.

Occupational Health Update: Evaluation and Management of Exposures and Postexposure Prophylaxis

Health care personnel (HCP) are at risk of exposure to infectious agents depending on their job duties and other factors. Risks include percutaneous exposure to blood-borne pathogens via sharp injuries (eg, human immunodeficiency virus, hepatitis B virus, hepatitis C virus); exposure by direct contact, droplet, or airborne transmission of pathogens through direct patient care (eg, pertussis, invasive meningococcus infections, tuberculosis); and through indirect contact transmission related to the contaminated health care environment (eg, Clostridioides difficile). Occupational health programs must effectively identify and respond to potential exposures and provide guidance to HCP on postexposure prophylaxis.

Herd Protection against Meningococcal Disease through Vaccination

Reduction in the transmission of Neisseria meningitidis within a population results in fewer invasive disease cases. Vaccination with meningococcal vaccines composed of high weight capsular polysaccharide without carrier proteins has minimal effect against carriage or the acquisition of carriage. Conjugate vaccines, however, elicit an enhanced immune response which serves to reduce carriage acquisition and hinder onwards transmission. Since the 1990s, several meningococcal conjugate vaccines have been developed and, when used in age groups associated with higher carriage, they have been shown to provide indirect protection to unvaccinated cohorts. This herd protective effect is important in enhancing the efficiency and impact of vaccination. Studies are ongoing to assess the effect of protein-based group B vaccines on carriage; however, current data cast doubt on their ability to reduce transmission.

Declining Incidence of Invasive Meningococcal Disease in South Africa: 2003-2016

BACKGROUND

Invasive meningococcal disease (IMD) is endemic to South Africa, where vaccine use is negligible. We describe the epidemiology of IMD in South Africa.

METHODS

IMD cases were identified through a national, laboratory-based surveillance program, GERMS-SA, from 2003-2016. Clinical data on outcomes and human immunodeficiency virus (HIV) statuses were available from 26 sentinel hospital sites. We conducted space-time analyses to detect clusters of serogroup-specific IMD cases.

RESULTS

Over 14 years, 5249 IMD cases were identified. The incidence was 0.97 cases per 100 000 persons in 2003, peaked at 1.4 cases per 100 000 persons in 2006, and declined to 0.23 cases per 100 000 persons in 2016. Serogroups were confirmed in 3917 (75%) cases: serogroup A was present in 4.7% of cases, B in 23.3%, C in 9.4%; W in 49.5%; Y in 12.3%, X in 0.3%; Z in 0.1% and 0.4% of cases were non-groupable. We identified 8 serogroup-specific, geo-temporal clusters of disease. Isolate susceptibility was 100% to ceftriaxone, 95% to penicillin, and 99.9% to ciprofloxacin. The in-hospital case-fatality rate was 17% (247/1479). Of those tested, 36% (337/947) of IMD cases were HIV-coinfected. The IMD incidence in HIV-infected persons was higher for all age categories, with an age-adjusted relative risk ratio (aRRR) of 2.5 (95% confidence interval [CI] 2.2-2.8; P < .001) from 2012-2016. No patients reported previous meningococcal vaccine exposure. Patients with serogroup W were 3 times more likely to present with severe disease than those with serogroup B (aRRR 2.7, 95% CI 1.1-6.3); HIV coinfection was twice as common with W and Y diseases (aRRR W = 1.8, 95% CI 1.1-2.9; aRRR Y = 1.9, 95% CI 1.0-3.4).

CONCLUSIONS

In the absence of significant vaccine use, IMD in South Africa decreased by 76% from 2003-2016. HIV was associated with an increased risk of IMD, especially for serogroup W and Y diseases.

Phenotypic characterization of Neisseria meningitidis strains isolated from invasive meningococcal disease in Brazil from 2002 to 2017

Introduction

Invasive meningococcal disease (IMD) has a high rate of fatality and may cause severe clinical sequelae. Over the years, the epidemiology of IMD has changed significantly in various regions of the world, and laboratory surveillance of this disease is important for mapping epidemiologic changes.

Aim

To perform phenotypic characterization of Neisseria meningitidis strains isolated from invasive disease in Brazil from 2002 to 2017, as a complementation of the data obtained in the period of 1990-2001.

Methodology

In total, 8,689 isolates sent to Adolfo Lutz Institute confirmed as N. meningitidis by conventional methods were serogrouped by slide agglutination against MenA, MenB, MenC, MenE, MenW, MenX, MenY and MenZ; serotyped and serosubtyped by a whole-cell dot-blotting assay with monoclonal antibodies.

Results

The isolates were sent from all regions of Brazil, and the southeast region was responsible for the largest number of isolates (57.2 %). Overall, the total sample (n=8,689) was represented by serogroups C (n=4,729; 54.4 %), B (n=3,313; 38.1 %), W (n=423; 4.9 %), Y (n=203; 2.3 %), X (n=5; 0.1 %) and others (n=16; 0.2 %). A shift in the prevalence of serogroups was observed in 2006, when serogroup C became the most prevalent (65.5 %), surpassing the serogroup B (21.9 %). The main isolated phenotypes were C:23:P1.14-6; B:4,7:P1.19,15; W:2a:P1.5 and W:2a:P1.5,2.

Conclusion

The data show an important change in the distribution of meningococcal serogroups, serotypes and subtypes occurring during 2002-2017. A continuous laboratory-based surveillance provides robust information to implement appropriate strategies to IMD control.

Immunogenicity and safety of a meningococcal serogroups A and C tetanus toxoid conjugate vaccine (MenAC-TT): two immune schedules in toddles aged 12-23 months in China

Background: This exploratory study aimed to assess the immunogenicity and safety of 1 and 2 doses of meningococcal serogroups A and C tetanus toxoid-conjugate vaccine (MenAC-TT) in toddles.Methods: Healthy participants aged 12-23 months were randomized into two groups to receive 1 or 2 doses of the tested vaccine. The interval was 28 days between two doses. Blood samples were collected at day 0 before the immunization and day 28 post-each dose. Safety observation was conducted during 28 days after each vaccination. Serious adverse event (SAE) was conducted throughout 6 month observation period.Results: Overall 301 toddles were vaccinated. Twenty-eight days post full-course vaccination, ≥97.20% toddles had titers ≥1:8 and ≥81.48% had titers ≥1:128 for MenA and MenC in the two schedules groups. There were no significant differences between the two schedule groups for each titer thresholds and serogroups. Up to month 12 post the first dose, titers ≥1:8 and 1:128 were declined to 71.32-80.83% and 26.67-57.85% for each meningococcal serogroups. Most adverse reactions (ARs) were mild or moderate, and the incidence of grade 3 ARs was below 3.33%. The incidence of redness was significantly higher in the two doses group than that in the one dose group, in terms of grade 1 and grade 2 were higher. No SAEs were considered causally related to vaccination.Conclusion: The MenAC-TT showed similarly safety and immunogenicity profile in toddles with two schedules. It will be more important to provide the data for formulating appropriate immunization strategies in different age groups in China.

Outbreaks of meningococcal meningitis in non-African countries over the last 50 years: a systematic review

Background

Meningococcal disease is caused by the bacteria Neisseria meningitidis, leading to substantial mortality and severe morbidity; with serogroups A, B, C, W135, X and Y most significant in causing disease. An outbreak is defined as multiple cases of the same serogroup occurring in a population over a short time-period. A systematic review was performed to gain insight into outbreaks of meningococcal disease and to describe the temporal pattern over the last 50 years in non-African countries.

Methods

PubMed and EMBASE were searched for English-language publications on outbreaks of meningococcal disease in non-African countries between January 1966 and July 2017, with an additional grey literature search. Articles and reports were considered eligible if they reported confirmed meningococcal outbreak cases, included the region, number of cases, and the start and end dates of the outbreak. Data on outbreaks was stratified by geographical region in accordance with the World Health Organization (WHO) regional classification, and case-fatality rates (CFRs) were calculated.

Results

Of the identified publications, 3067 were screened and 73 included, reporting data from 83 outbreaks. The majority of outbreaks were identified in the regions of the Americas (41/83 outbreaks), followed by the European region (30/83 outbreaks). In each of the Western Pacific, Eastern Mediterranean, and South-East Asian regions there were <10 outbreaks reported. The predominant serogroup in the majority of outbreaks was serogroup C (61%), followed by serogroup B (29%), serogroup A (5%) and serogroup W135 (4%). Outbreaks showed a peak in the colder months of both the Northern and Southern Hemispheres. Of the 54 outbreaks where CFR was calculable for all outbreak cases, it ranged from 0%-80%.

Conclusions

These data present a retrospective view of the patterns for meningococcal disease outbreaks in non-African countries, and provide valuable data for monitoring future changes in disease epidemiology and informing preventive measures.

Development of a PCR algorithm to detect and characterize Neisseria meningitidis carriage isolates in the African meningitis belt

Improved methods for the detection and characterization of carried Neisseria meningitidis isolates are needed. We evaluated a multiplex PCR algorithm for the detection of a variety of carriage strains in the meningitis belt. To further improve the sensitivity and specificity of the existing PCR assays, primers for gel-based PCR assays (sodC, H, Z) and primers/probe for real-time quantitative PCR (qPCR) assays (porA, cnl, sodC, H, E, Z) were modified or created using Primer Express software. Optimized multiplex PCR assays were tested on 247 well-characterised carriage isolates from six countries of the African meningitis belt. The PCR algorithm developed enabled the detection of N. meningitidis species using gel-based and real-time multiplex PCR targeting porA, sodC, cnl and characterization of capsule genes through sequential multiplex PCR assays for genogroups (A, W, X, then B, C, Y and finally H, E and Z). Targeting both porA and sodC genes together allowed the detection of meningococci with a sensitivity of 96% and 89% and a specificity of 78% and 67%, for qPCR and gel-based PCR respectively. The sensitivity and specificity ranges for capsular genogrouping of N. meningitidis are 67% - 100% and 98%-100% respectively for gel-based PCR and 90%-100% and 99%-100% for qPCR. We developed a PCR algorithm that allows simple, rapid and systematic detection and characterisation of most major and minor N. meningitidis capsular groups, including uncommon capsular groups (H, E, Z).

Characterization of strains of Neisseria meningitidis causing meningococcal meningitis in Mozambique, 2014: Implications for vaccination against meningococcal meningitis

INTRODUCTION

In sub Saharan Africa, the epidemiology, including the distribution of serogroups of strains of N. meningitidis is poorly investigated in countries outside "the meningitis belt". This study was conducted with the aim to determine the distribution of serogroups of strains of N. meningitidis causing meningococcal meningitis in children and adults in Mozambique.

METHODS

A total of 106 PCR confirmed Neisseria meningitidis Cerebrospinal Fluid (CSF) samples or isolates were obtained from the biobank of acute bacterial meningitis (ABM) surveillance being implemented by the National Institute of Health, at three central hospitals in Mozambique, from January to December 2014. Serogroups of N. meningitidis were determined using conventional PCR, targeting siaD gene for Neisseria meningitidis. Outer Membrane Proteins (OMP) Genotyping was performed by amplifying porA gene in nine samples.

RESULTS

Of the 106 PCR confirmed Neisseria meningitidis samples, the most frequent serotype was A (50.0%, 53/106), followed by W/Y (18.9%, 20/106), C (8.5%, 9/106), X (7.5%, 8/106) and B (0.9%, 1/106). We found non-groupable strains in a total of 15 (14.2%) samples. PorA genotypes from nine strains showed expected patterns with the exception of two serogroup C strains with P1.19,15,36 and P1.19-36,15 and one serogroup X with P1.19,15,36, variants frequently associated to serogroup B.

CONCLUSION

Our data shows that the number of cases of meningococcal meningitis routinely reported in central hospitals in Mozambique is significant and the most dominant serogroup is A. In conclusion, although serogroup A has almost been eliminated from the "meningitis belt", this serogroup remains a major concern in countries outside the belt such as Mozambique.

Meningococcal Quadrivalent Tetanus Toxoid Conjugate Vaccine (MenACWY-TT; Nimenrix®): A Review

MenACWY-TT (Nimenrix^®) is a quadrivalent meningococcal tetanus toxoid conjugate vaccine licensed in Europe for active immunisation of individuals aged ≥ 6 weeks against invasive disease caused by Neisseria meningitidis capsular groups A, C, W and Y. MenACWY-TT is the first quadrivalent conjugate vaccine to be approved in Europe for use in infants as young as 6 weeks of age. Numerous phase II-IIIb clinical studies showed that intramuscular MenACWY-TT administered as primary or booster vaccination was highly immunogenic for all four vaccine capsular groups and had an acceptable reactogenicity profile in individuals aged 6 weeks to ≥ 56 years. MenACWY-TT is as immunogenic and safe as other previously licensed monovalent capsular group C or quadrivalent capsular groups A, C, W and Y meningococcal vaccines and can be coadministered with other routine vaccines without adversely affecting the immunogenicity or safety profiles of either vaccine. Current data indicate that primary and booster vaccination with MenACWY-TT is a valuable and safe option for broadening meningococcal protection against four capsular groups across a broad age range, starting as early as 6 weeks of age.

Point-of-care C reactive protein to identify serious infection in acutely ill children presenting to hospital: prospective cohort study

OBJECTIVE

Acute infection is the most common presentation of children to hospital. A minority of these infections are serious, but early recognition and adequate management are essential. We aimed to develop improved tools to assess children attending ambulatory hospital care, integrating clinical features with point-of-care C reactive protein (CRP).

DESIGN

Prospective observational diagnostic study.

SETTING AND PATIENTS

5517 acutely ill children (1 month-16 years) presenting to 106 paediatricians at six outpatient clinics and six emergency departments in Belgium.

INDEX TEST

Point-of-care CRP alongside vital signs and objective symptoms measurements.

MAIN OUTCOME

Hospital admission for >24 hours with a serious infection <5 days after presentation.

RESULTS

An algorithm was developed consisting of clinical features and CRP. This achieved 97.1% (95% CI 94.3% to 98.7%) sensitivity and 99.6% (95% CI 99.2% to 99.8%) negative predictive value, excluding serious infections in 36.4% of children. It stratifies patients into three groups based on CRP level: high-risk group with CRP >75 mg/L (26.8% risk of infection), intermediate-risk group with CRP 20-75 mg/L and at least one of seven clinical features (8.1%), and lower risk group with CRP <20 mg/L with at least one of the 11 features (3.8%). Children in intermediate-risk or low-risk groups with normal clinical assessment have 0.6% and 0.4% risk of serious infections, respectively.

CONCLUSIONS

Conducting a CRP test may first enable children to be stratified into three risk groups, guiding assessment of clinical features that could be performed by junior doctors or nurses. In one-third of acutely ill children, the algorithm could exclude serious infection. Prospective validation of the algorithm is needed.

CLINICAL TRIAL REGISTRATION

NCT02024282 (post-results).

Prevalence and genetic characteristics of 4CMenB and rLP2086 vaccine candidates among Neisseria meningitidis serogroup B strains, China

OBJECTIVE

To systematically investigate the prevalence and genetic characteristics of 4CMenB and rLP2086 vaccine candidates among Neisseria meningitidis serogroup B (NmB) in China.

METHODS

A total of 485 NmB strains isolated in 29 provinces of China between 1968 and 2016 were selected from the culture collection of the national reference laboratory according to the isolation year, location, and source. Multi-locus sequence typing (MLST) and porA gene sequencing were performed on all 485 study strains; PCR was used to detect the fHbp, nadA, and nhba gene of 432 strains; positive amplification products from the fHbp and nadA genes from all strains, as well as those of the nhba gene from 172 representative strains, were sequenced.

RESULTS

MLST results showed that the predominant (putative) clonal complexes (CCs) of NmB isolates have changed over time in China. While strains that could not be assigned to existing (p)CCs were the biggest proportion, CC4821 was the most prevalent lineage (36.0%) since 2005. PCR and sequence analysis revealed that the 4CMenB and rLP2086 vaccine candidates were highly diverse. Respectively, 152 PorA genotypes and 83 VR2 sequences were identified with significant diversity within a single CC; the complete nadA gene was found in ten of 432 study strains; fHbp was present in most strains (422/432) with variant 2 predominating (82.9%) in both patient- and carrier- derived isolates; almost all strains harbored the nhba gene while sequences were diverse.

CONCLUSIONS

With regards to clonal lineages and vaccine candidate proteins, NmB isolates from China were generally diverse. Further studies should be performed to evaluate the cross-protection of present vaccines against Chinese NmB strains.

Bioengineered polyester beads co-displaying protein and carbohydrate-based antigens induce protective immunity against bacterial infection

The efficacy of protein and carbohydrate antigens as vaccines can be improved via particulate delivery strategies. Here, protein and carbohydrate antigens used in formulations of vaccines against Neisseria menigitidis were displayed on in vivo assembled polyester beads using a combined bioengineering and conjugation approach. An endotoxin-free mutant of Escherichia coli was engineered to produce translational fusions of antigens (Neisseria adhesin A (NadA) and factor H binding protein (fHbp) derived from serogroup B) to the polyhydroxybutyrate synthase (PhaC), in order to intracellularly assemble polyester beads displaying the respective antigens. Purified beads displaying NadA showed enhanced immunogenicity compared to soluble NadA. Both soluble and particulate NadA elicited functional antibodies with bactericidal activity associated with protective immunity. To expand the antigen repertoire and to design a more broadly protective vaccine, NadA-PhaC beads were additionally conjugated to the capsular polysaccharide from serogroup C. Co-delivery of surface displayed NadA and the capsular polysaccharide induced a strong and specific Th1/Th17 mediated immune response associated with functional bactericidal antibodies. Our findings provide the foundation for the design of multivalent antigen-coated polyester beads as suitable carriers for protein and polysaccharide antigens in order to induce protective immunity.

Meningococcal disease, a clinical and epidemiological review

Meningococcal disease is the acute infection caused by Neisseria meningitidis, which has humans as the only natural host. The disease is widespread around the globe and is known for its epidemical potential and high rates of lethality and morbidity. The highest number of cases of the disease is registered in the semi-arid regions of sub-Saharan Africa. In Brazil, it is endemic with occasional outbreaks, epidemics and sporadic cases occurring throughout the year, especially in the winter. The major epidemics of the disease occurred in Brazil in the 70's caused by serogroups A and C. Serogroups B, C and Y represent the majority of cases in Europe, the Americas and Australia. However, there has been a growing increase in serogroup W in some areas. The pathogen transmission happens for respiratory route (droplets) and clinically can lead to meningitis and sepsis (meningococcemia). The treatment is made with antimicrobial and supportive care. For successful prevention, we have some measures like vaccination, chemoprophylaxis and droplets' precautions. In this review, we have described and clarify clinical features of the disease caused by N. meningitidis regarding its relevance for healthcare professionals.

Capsule switching of Neisseria meningitidis sequence type 7 serogroup A to serogroup X

OBJECTIVES

The bacterial pathogen Neisseria meningitidis is able to escape the currently available capsule-based vaccines by undergoing capsule switching. In this study, we investigated whether capsule switching has occurred in a recently emerged sequence type (ST) 7 serogroup X isolate in China, for which currently no vaccine is available.

METHODS

To identify capsule switching breakpoints, the capsule locus and flanking regions of the ST-7 serogroup X isolate and three endemic ST-7 serogroup A isolates were sequenced and compared. To obtain further insight into capsule switching frequency and length of DNA fragments involved, capsule switching assays were performed using genomic DNA containing combinations of antibiotic selection markers at various locations in the capsule locus and flanking regions.

RESULTS

Sequence analyses showed that capsule switching has occurred and involved a 8450 bp serogroup X DNA fragment spanning the region from galE to ctrC. Capsule switching assays indicate that capsule switching occurs at a frequency of 6.3 × 10^-6 per bacterium per μg of DNA and predominantly involved DNA fragments of about 8.1-9.6 kb in length.

CONCLUSIONS

Our results show that capsule switching in N. meningitidis occurs at high frequency and involves recombination in the flanking regions of the capsule biosynthesis genes.

Genetic Analysis of Neisseria meningitidis Sequence Type 7 Serogroup X Originating from Serogroup A

Neisseria meningitidis causes meningococcal disease, often resulting in fulminant meningitis, sepsis, and death. Vaccination programs have been developed to prevent infection of this pathogen, but serogroup replacement is a problem. Capsular switching has been an important survival mechanism for N. meningitidis, allowing the organism to evolve in the present vaccine era. However, related mechanisms have not been completely elucidated. Genetic analysis of capsular switching between diverse serogroups would help further our understanding of this pathogen. In this study, we analyzed the genetic characteristics of the sequence type 7 (ST-7) serogroup X strain that was predicted to arise from ST-7 serogroup A at the genomic level. By comparing the genomic structures and sequences, ST-7 serogroup X was closest to ST-7 serogroup A, whereas eight probable recombination regions, including the capsular gene locus, were identified. This indicated that serogroup X originated from serogroup A by recombination leading to capsular switching. The recombination involved approximately 8,540 bp from the end of the ctrC gene to the middle of the galE gene. There were more recombination regions and strain-specific single-nucleotide polymorphisms in serogroup X than in serogroup A genomes. However, no specific gene was found for each serogroup except those in the capsule gene locus.

Meningococcal disease: has the battle been won?

Meningococcal disease is a worldwide life-threatening infection associated in many cases with debilitating long-term sequelae, both within the military and civilian populations. Military recruits are at a higher risk of acquiring this infection due to numerous factors, such as young recruits in the age group 18-25 years, high carriage rates of meningococci, communal and crowed living quarters and global deployment or training in regions with different meningococcal serogroup epidemiology. Although these increased risk factors among young recruits remain, the increased incidence of disease is now historic. Numerous outbreaks have been reported among military personnel, however although the incidence of the disease continues to decrease, there are still sporadic cases. The non-specific symptoms, sudden onset and rapid progression of the infection results in a limited time frame to both diagnose and successfully treat the patient. Many developments have been made in relation to the microbiological diagnosis of the disease, particularly in the era of molecular diagnostics, which have the potential to diagnose the infection more quickly. Developments in vaccinology, and in particular with relation to biotechnology and reverse vaccinology, have led to the availability of new meningococcal vaccines, further enabling disease prevention. This paper outlines the history of meningococcal disease in relation to the military and highlights the new developments in both diagnostics and vaccination, which have the potential to diagnose, treat and control meningococcal disease in a more efficient manner.

Vaccines for the prevention of meningococcal capsular group B disease: What have we recently learned?

Meningococcal disease remains a feared and devastating cause of sepsis and meningitis. Disease incidence is highest among infants and children although a significant burden of disease is experienced by adolescents, young adults and those with specific risk-factors. Prevention of disease against capsular groups A, C, W and Y; 4 of the 5 most pathogenic groups is achievable using capsular polysaccharide vaccines. It has only recently been possible to provide protection against capsular group B (MenB) strains following the licensure of a 4 component group B vaccine (4CMenB) in Europe in 2013. Following licensure, 4CMenB has been used in specific at-risk groups and in response to outbreaks of MenB disease. The largest outbreak interventions have been in students at 2 universities in the United States and for all individuals aged 2 months to 20 years of age in Quebec, Canada. The vaccine was recommended in February 2014 for implementation into the UK infant schedule at 2, 4 and 12 months of age, although it has taken over 12 months to resolve procurement discussions to enable implementation. The UK recommendation incorporates prophylactic paracetamol with infant doses when 4CMenB is administered concomitantly with routine vaccines. This is based on recent data demonstrating the ability of paracetamol to reduce fever rates to background levels without impacting immunogenicity. Post-implementation surveillance will be important to provide vaccine efficacy data as this was not possible to determine in pre-licensure studies due to the relative infrequency of MenB cases.

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.

Occupational Health Update: Focus on Preventing the Acquisition of Infections with Pre-exposure Prophylaxis and Postexposure Prophylaxis

Health care personnel are commonly exposed to infectious agents via sharp injuries (eg, human immunodeficiency virus, hepatitis B virus, and hepatitis C virus), direct patient care (eg, pertussis and meningococcus), and the contaminated environment (eg, Clostridium difficile). An effective occupational program is a key aspect of preventing acquisition of an infection by offering the following: (1) education of health care personnel regarding proper handling of sharps, early identification and isolation of potentially infectious patients, and hand hygiene; (2) assuring immunity to vaccine-preventable diseases; and, (3) immediate availability of a medical evaluation after a nonprotected exposure to an infectious disease.

Invasive Meningococcal Meningitis Serogroup C Outbreak in Northwest Nigeria, 2015 - Third Consecutive Outbreak of a New Strain

BACKGROUND: In northwest Nigeria in 2013 and 2014, two sequential, localized outbreaks of meningitis were caused by a new strain of Neisseria meningitidis serogroup C (NmC). In 2015, an outbreak caused by the same novel NmC strain occurred over a wider geographical area, displaying different characteristics to the previous outbreaks. We describe cases treated by Médecins Sans Frontières (MSF) in the 2015 outbreak. 

METHODS: From February 10 to June 8, 2015, data on cerebrospinal meningitis (CSM) cases and deaths were recorded on standardized line-lists from case management sites supported by MSF. Cerebrospinal fluid (CSF) samples from suspected cases at the beginning of the outbreak and throughout from suspected cases from new geographical areas were tested using rapid Pastorex® latex agglutination to determine causative serogroup. A subset of CSF samples was also inoculated into Trans-Isolate medium for testing by the WHO Collaborating Centre for Reference and Research on Meningococci, Oslo. Reactive vaccination campaigns with meningococcal ACWY polysaccharide vaccine targeted affected administrative wards. 

RESULTS: A total of 6394 (65 confirmed and 6329 probable) cases of CSM including 321 deaths (case fatality rate: 5.0%) were recorded. The cumulative attack rate was 282 cases per 100,000 population in the wards affected. The outbreak lasted 17 weeks, affecting 1039 villages in 21 local government areas in three states (Kebbi, Sokoto, Niger). Pastorex® tests were NmC positive for 65 (58%) of 113 CSF samples. Of 31 Trans-Isolate medium samples, 26 (84%) tested positive for NmC (14 through culture and 12 through PCR); all had the same rare PorA type P1.21-15,16 as isolates from the 2013 and 2014 outbreaks. All 14 culture-positive samples yielded isolates of the same genotype (ST-10217 PorA type P1.21-15,16 and FetA type F1-7). More than 222,000 targeted individuals were vaccinated relatively early in the outbreak (administrative coverage estimates 98% and 89% in Kebbi and Sokoto, respectively). 

CONCLUSIONS: The outbreak was the largest caused by NmC documented in Nigeria. Reactive vaccination in both states may have helped curtail the epidemic. A vaccination campaign against NmC with a long-lasting conjugate vaccine should be considered in the region.

Fast and accurate dynamic estimation of field effectiveness of meningococcal vaccines

BACKGROUND

Estimating the effectiveness of meningococcal vaccines with high accuracy and precision can be challenging due to the low incidence of the invasive disease, which ranges between 0.5 and 1 cases per 100,000 in Europe and North America. Vaccine effectiveness (VE) is usually estimated with a screening method that combines in one formula the proportion of meningococcal disease cases that have been vaccinated and the proportion of vaccinated in the overall population. Due to the small number of cases, initial point estimates are affected by large uncertainties and several years may be required to estimate VE with a small confidence interval.

METHODS

We used a Monte Carlo maximum likelihood (MCML) approach to estimate the effectiveness of meningococcal vaccines, based on stochastic simulations of a dynamic model for meningococcal transmission and vaccination. We calibrated the model to describe two immunization campaigns: the campaign against MenC in England and the Bexsero campaign that started in the UK in September 2015. First, the MCML method provided estimates for both the direct and indirect effects of the MenC vaccine that were validated against results published in the literature. Then, we assessed the performance of the MCML method in terms of time gain with respect to the screening method under different assumptions of VE for Bexsero.

RESULTS

MCML estimates of VE for the MenC immunization campaign are in good agreement with results based on the screening method and carriage studies, yet characterized by smaller confidence intervals and obtained using only incidence data collected within 2 years of scheduled vaccination. Also, we show that the MCML method could provide a fast and accurate estimate of the effectiveness of Bexsero, with a time gain, with respect to the screening method, that could range from 2 to 15 years, depending on the value of VE measured from field data.

CONCLUSIONS

Results indicate that inference methods based on dynamic computational models can be successfully used to quantify in near real time the effectiveness of immunization campaigns against Neisseria meningitidis. Such an approach could represent an important tool to complement and support traditional observational studies, in the initial phase of a campaign.

Meningococcal Vaccinations

Neisseria meningitidis, a gram-negative diplococcal bacterium, is a common asymptomatic nasopharyngeal colonizer that may infrequently lead to invasive disease in the form of meningitis or bacteremia. Six serogroups (A, B, C, W, X and Y) are responsible for the majority of invasive infections. Increased risk of disease occurs in specific population groups including infants, adolescents, those with asplenia or complement deficiencies, and those residing in crowded living conditions such as in college dormitories. The incidence of invasive meningococcal disease varies geographically with some countries (e.g., in the African meningitis belt) having both high endemic disease rates and ongoing epidemics, with annual rates reaching 1000 cases per 100,000 persons. Given the significant morbidity and mortality associated with meningococcal disease, it remains a major global health threat best prevented by vaccination. Several countries have implemented vaccination programs with the selection of specific vaccine(s) based on locally prevalent serogroup(s) of N. meningitidis and targeting population groups at highest risk. Polysaccharide meningococcal vaccines became available over 40 years ago, but are limited by their inability to produce immunologic memory responses, poor immunogenicity in infants/children, hyporesponsiveness after repeated doses, and lack of efficacy against nasopharyngeal carriage. In 1999, the first meningococcal conjugate vaccines were introduced and have been successful in overcoming many of the shortcomings of polysaccharide vaccines. The implementation of meningococcal conjugate vaccination programs in many areas of the world (including the massive campaign in sub-Saharan Africa using a serogroup A conjugate vaccine) has led to dramatic reductions in the incidence of meningococcal disease by both individual and population protection. Progressive advances in vaccinology have led to the recent licensure of two effective vaccines against serogroup B [MenB-4C (Bexsero) and MenB-FHbp (Trumenba)]. Overall, the evolution of novel meningococcal vaccines and the effective implementation of targeted vaccination programs has led to a substantial decrease in the burden of disease worldwide representing a major public health accomplishment.

Safety and immunogenicity of a single dose of a quadrivalent meningococcal conjugate vaccine (MenACYW-D): a multicenter, blind-observer, randomized, phase III clinical trial in the Republic of Korea

OBJECTIVES

To assess the safety and immunogenicity of a meningococcal polysaccharide diphtheria toxoid conjugate vaccine (MenACYW-D) in a Korean population.

METHODS

This was a phase III, blind-observer, controlled study in which participants aged 11-55 years were randomized (2:1 ratio) to a single dose of MenACYW-D or tetanus/diphtheria/acellular pertussis (Tdap) vaccine. Outcomes included rates of seroconversion against all serogroups (≥4-fold increase in antibody titer from pre-vaccination), geometric mean titers (GMTs) at days 0 and 28 based on a serum bactericidal assay using baby rabbit complement, rates of seroprotection (titer ≥1:128) at day 28, and safety.

RESULTS

A total of 300 participants were enrolled in the study (200 MenACYW-D and 100 Tdap). Seroconversion rates for serogroups A, C, Y, and W-135 were 77.8%, 88.3%, 74.6%, and 92.4%, respectively, for the MenACYW-D group and 9.3%, 8.1%, 12.2%, and 8.2%, respectively, for the Tdap group. The proportions of participants with pre-vaccination titers ≥1:128 were 57.3%, 12.6%, 51.5%, and 22.2% for serogroups A, C, Y, and W-135, respectively; post-vaccination rates were 98.5%, 89.4%, 96.0%, and 95.0% for the MenACYW-D group. A lower proportion of participants reported solicited reactions with MenACYW-D (46.2%) compared with Tdap (76.8%).

CONCLUSION

A single dose of MenACYW-D was well tolerated and elicited a robust immune response in Korean adolescents and adults.

Epidemiology of Neisseria meningitidis infections: case distribution by age and relevance of carriage

Notwithstanding different meningococcal serogroups have changed their distribution and their impact in different age classes over time, N. meningitidis' invasive diseases are a major public health issue worldwide, due to the related complications and severe sequelae. Nowadays, the highest rates of invasive disease are registered in children younger than 1 year of age, with a second lesser peak in adolescents and young adults (15-25 years of age). On the contrary, the prevalence of carriage is low in newborns and in school-age children, and increases during adolescence and young-adult age; then it decreases again in older age. N. meningitidis' infection prevalence has greatly decreased in Europe and North America thanks to the use of conjugate vaccines (MenC and MenACWY) as well as the incidence of invasive disease due to serogroup A in sub-saharian Africa after the introduction of MenAfriVac conjugate vaccine. The great success of conjugate vaccines is related not only to the direct protection from disease but also to the impact on carriage; this latter allows an indirect protection of unimmunized subjects. For these reasons, the implementation of immunization with the new generation vaccines in the age classes most impacted by disease and carriage (first year of life, adolescence and young adulthood) could permit to achieve an extraordinary decrease of the incidence of meningococcal disease.

Climate Regimes, El Niño-Southern Oscillation, and Meningococcal Meningitis Epidemics

Meningococcal meningitis is a major public health problem that kills thousands annually in Africa, Europe, North, and South America. Occurrence is, however, highest during the dry seasons in Sahel Africa. Interannual changes in precipitation correlate with interannual changes in El Niño-Southern Oscillation (ENSO), while interdecadal changes in precipitation correlate with Pacific Decadal Oscillation (PDO). The objective of the study was to determine if there is spectral coherence of seasonal, interannual, and interdecadal changes in occurrence of meningococcal meningitis in Sahel, Central, and East Africa with interannual and interdecadal changes of PDO and ENSO. Time series were fitted to occurrence of meningococcal meningitis in Sahel, Central, and East Africa, to indices of precipitation anomalies in the Sahel, and to indices of ENSO and PDO anomalies. Morlet wavelet was used to transform the time series to frequency-time domain. Wavelet spectra and coherence analyses were performed. Occurrence of meningococcal meningitis showed seasonal, interannual, and interdecadal changes. The magnitude of occurrence was higher during warm climate regime, and strong El Niños. Spectra coherence of interannual and interdecadal changes of ENSO and PDO with occurrence of meningococcal meningitis in Sahel, Central, and East Africa were significant at p < 0.0001. Precipitation in Sahel was low during warm climate regimes. Spectra coherence of changes in precipitation in Sahel with ENSO was significant at p < 0.0001. ENSO and PDO are determinants of the seasonal, interannual, and interdecadal changes in occurrence of meningococcal meningitis. Public health management of epidemics of meningococcal meningitis should include forecast models of changes in ENSO to predict periods of low precipitation, which initiate occurrence.

Development and Evaluation of a Multiplex Microsphere Assay for Quantitation of IgG and IgA Antibodies against Neisseria meningitidis Serogroup A, C, W, and Y Polysaccharides

We developed and evaluated a rapid and simple multiplex microsphere assay for the quantification of specific IgG and IgA antibodies against meningococcal serogroup A, C, W, and Y capsular polysaccharides in serum and saliva. Meningococcal polysaccharides were conjugated to distinct magnetic carboxylated microspheres, and the performance of the assay was assessed using the CDC1992 standard meningococcal reference serum and a panel of serum and saliva samples. The standard curve was linear over an eight 3-fold dilution range in the IgG assay and a seven 3-fold dilution range in the IgA assay. No cross-reactivity was discovered, and the assay showed high specificity with ≥91% homologous inhibition and ≤11% heterologous inhibition for all serogroups and immunoglobulin classes. Lower limits of detections were ≤280 pg/ml for IgG and ≤920 pg/ml for IgA antibodies. The assay was reproducible, with a mean coefficient of variation of ≤5% for intra-assay duplicates, a mean coefficient of variation of ≤20% for interassay repeated analysis with different conjugations of microspheres, and a mean coefficient of variation within 25.8% for interoperator variation. The assay showed good correlation to the standard meningococcal polysaccharide enzyme-linked immunosorbent assay (ELISA) for detection of serum antibodies. This multiplex assay is robust and reliable and requires less sample volume, and less time and workload are needed than for ELISA, making this method highly relevant for serological and salivary investigations on the effect of meningococcal vaccines and for immunosurveillance studies.

Primary meningococcal polyarthritis in an adult woman

Primary joint infection caused by the Gram-negative bacteria Neisseria meningitidis is rare. Normally, joint involvement comes secondary to meningitis or severe sepsis caused by this agent. When primary arthritis is seen, monoarthritis is the most common presentation. A meningococcal polyarthritis is described in less than 10 case reports according to current literature. This case report aims to briefly review this rare clinical event in an adult woman with no previous history of rheumatological disease. Early diagnosis of polyarthritis caused by meningococcal bacteria usually present a good prognosis when properly treated.

Bacterial etiologies of five core syndromes: laboratory-based syndromic surveillance conducted in Guangxi, China

BACKGROUND

Under the existing national surveillance system in China for selected infectious diseases, bacterial cultures are performed for only a small percentage of reported cases. We set up a laboratory-based syndromic surveillance system to elucidate bacterial etiologic spectrum and detect infection by rare etiologies (or serogroups) for five core syndromes in the given study area.

METHODS

Patients presenting with one of five core syndromes at nine sentinel hospitals in Guagnxi, China were evaluated using laboratory-based syndrome surveillance to elucidate bacterial etiologies. We collected respiratory and stool specimens, as well as CSF, blood and other related samples for bacterial cultures and pulse field gel electrophoresis (PFGE) assays.

RESULTS

From February 2009 to December 2011, 2,964 patients were enrolled in the study. Etiologies were identified in 320 (10.08%) patients. Streptococcus pneumonia (37 strains, 24.18%), Klebsiella pneumonia (34, 22.22%), Pseudomonas aeruginosa (19, 12.42%) and Haemophilus influenza (18, 11.76%) were the most frequent pathogens for fever and respiratory syndrome, while Salmonella (77, 81.05%) was most often seen in diarrhea syndrome cases. Salmonella paratyphi A (38, 86.36%) occurred in fever and rash syndrome, with Cryptococcus neoformans (20, 35.09%), Streptococcus pneumonia (5, 8.77%), Klebsiella pneumonia (5, 8.77%),streptococcus suis (3, 5.26%) and Neisseria meningitides group B (2, 3.51%) being the most frequently detected in encephalitis-meningitis syndrome. To date no pathogen was isolated from the specimens from fever and hemorrhage patients.

CONCLUSIONS

In addition to common bacterial pathogens, opportunistic pathogens and fungal infections require more attention. Our study contributes to the strengthening of the existing national surveillance system and provides references for other regions that are similar to the study area.