Epidemiology and prevention of meningococcal disease: a critical appraisal of vaccine policies

Epidemiology of invasive meningococcal disease and sequelae in the United Kingdom during the period 2008 to 2017 - a secondary database analysis

Background

Invasive meningococcal disease (IMD) causes high fatality in untreated patients alongside long-term sequelae in 20% survivors. For a comprehensive assessment of epidemiology, an analysis of these sequelae is required. This study aims to investigate the epidemiology of disease between 2008 and 2017 including a description of the sequelae, through the analysis of data collected from the UK Clinical Practice Research Datalink (CPRD) linked with data from the Hospital Episode Statistics (HES), and Office for National Statistics (ONS) mortality registry data.

Methods

This was a 10-year retrospective observational cohort study designed to describe the incidence, case-fatality rate (CFR) and occurrence of sequelae due to meningococcal disease, in the UK between 2007 and 2017 using data from the UK CPRD-HES-ONS. Cases were identified and matched on age, gender, date of diagnosis of IMD and followed-up-time with a control group without IMD. Demographics, clinical characteristics, mortality, and IMD-related sequelae were examined for IMD cases and compared with matched controls for a more comprehensive assessment.

Results

The study analysed 640 IMD patients with majority of the cases diagnosed (76.9%) in a hospital setting. Age-group analysis showed a decrease in the incidence rate of IMD in patients aged <1 year (30.4 – 7.5%) and an increase in those >50 years (10.4 – 27.8%). CFR was slightly higher among females, toddlers, and adults >50 years. No significant change in CFR was observed over study period. Case-control study showed a higher number of IMD sequelae among cases compared to age- and gender-matched controls, especially in those ≥ 50 years.

Conclusion

The study showed that, despite a relatively low incidence rate, IMD is responsible for a high CFR, namely in older age groups and by a high number of IMD sequelae. The study showed that leveraging data from existing databases can be used to complement surveillance data in truly assessing the epidemiology of IMD. Despite the availability of routine vaccination programs, IMD still poses a significant burden in the healthcare system of the UK. Optimization of vaccination programs may be required to reduce the disease burden.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12889-022-12933-3.

Translating meningococcal serogroup B vaccines for healthcare professionals

INTRODUCTION

Vaccination is an effective strategy to combat invasive meningococcal disease (IMD). Vaccines against the major disease-causing meningococcal serogroups are available; however, development of vaccines against serogroup B faced particular challenges, including the inability to target traditional meningococcal antigens (i.e. polysaccharide capsule) and limited alternative antigens due to serogroup B strain diversity. Two different recombinant, protein-based, serogroup B (MenB) vaccines that may address these challenges are currently available. These vaccines have been extensively evaluated in pre-licensure safety and immunogenicity trials, and recently in real-world studies on effectiveness, safety, and impact on disease burden.

AREAS COVERED

This review provides healthcare professionals, particularly pediatricians, an overview of currently available MenB vaccines, including development strategies and evaluation of coverage.

EXPERT OPINION

Overall, recombinant MenB vaccines are valuable tools for healthcare professionals to protect patients against IMD. Their development required innovative design approaches that overcame challenging hurdles and identified novel protein antigen targets; however, important distinctions in the approaches used in their development, evaluation, and administration exist and many unanswered questions remain. Healthcare providers frequently prescribing MenB vaccines are challenged to keep abreast of these differences to ensure patient protection against this serious disease.

Review of clinical studies comparing meningococcal serogroup C immune responses induced by MenACWY-TT and monovalent serogroup C vaccines

Many countries are replacing meningococcal serogroup C (MenC) conjugate vaccines (MCCV) with quadrivalent conjugate (MenACWY) vaccines, such as MenACWY-TT (Nimenrix®). This review examined eight studies comparing MenC immune responses induced by MenACWY-TT and MCCV to determine if these data support these changes. MenC serum bactericidal antibody levels using human (hSBA) or rabbit complement (rSBA) were evaluated at ~1 month postvaccination. Overall, ≥98.4% of infants administered 2 + 1 MenACWY-TT or MCCV schedules had rSBA titers ≥1:8 postprimary and postbooster vaccination; hSBA titers ≥1:8 were similar. In toddlers administered single MenACWY-TT or MCCV doses, ≥97.3% had rSBA titers ≥1:8 postvaccination; percentages with hSBA titers ≥1:8 were higher post-MenACWY-TT. Of children and adolescents receiving primary and booster MenACWY-TT and MCCV, ≥98.6% had rSBA titers ≥1:8; all children receiving MenACWY-TT or MCCV booster had hSBA titers ≥1:8 postdosing. MenC immune responses induced by MenACWY-TT are robust and generally comparable/superior to MCCV, supporting changes to recommendations.

Trajectory of serogroups causing Invasive Meningococcal Disease in Santa Catarina state, Brazil (2007–2019)

The aim of this study was to compare the trajectory of serogroups causing Invasive Meningococcal Disease (IMD) in the Santa Catarina (SC) state with those of whole Brazil. A retrospective analysis of all IMD cases reported from January 2007 to December 2019 was carried out. During the study period, 26,058 IMD cases were registered in Brazil and 644 and in SC state alone. Overall, Brazil showed progressive reduction in cases since 2010, when the meningococcal C conjugate vaccine was introducted on National Immunization Program, while SC showed an increase in total cases since 2013, particularly from serogroups W and C. Serogroups distribution was significantly different between Brazil and SC. The emergence of serogroup W highlights the improved meningococcal surveillance through increased accuracy in identification methods in SC state. This finding is important for discussing recommendations of quadrivalent (ACWY) conjugate vaccines in different geographical areas of Brazil.

Understanding the spatio-temporal dynamics of meningitis epidemics outside the belt: the case of the Democratic Republic of Congo (DRC)

BACKGROUND

Bacterial meningitis remains a major threat for the population of the meningitis belt. Between 2004 and 2009, in the countries of this belt, more than 200,000 people were infected with a 10% mortality rate. However, for almost 20 years, important meningitis epidemics are also reported outside this belt. Research is still very poorly developed in this part of the word like in the Democratic Republic of Congo (DRC), which experiences recurrent epidemics. This article describes for the first time the spatio-temporal patterns of meningitis cases and epidemics in DRC, in order to provide new insights for surveillance and control measures.

METHODS

Based on weekly suspected cases of meningitis (2000-2012), we used time-series analyses to explore the spatio-temporal dynamics of the disease. We also used both geographic information systems and geostatistics to identify spatial clusters of cases. Both using conventional statistics and the Cleveland's algorithm for decomposition into general trend, seasonal and residuals, we searched for the existence of seasonality.

RESULTS

We observed a low rate of biological confirmation of cases (11%) using soluble antigens search, culture and PCR. The main strains found are Streptococcus pneumoniae, Haemophilus influenzae and Neisseria meningitidis (A and C) serogroups. We identified 8 distinct spatial clusters, located in the northeastern and southeastern part of DRC, and in the capital city province, Kinshasa. A low seasonal trend was observed with higher incidence and attack rate of meningitis during the dry season, with a high heterogeneity in seasonal patterns occurring across the different districts and regions of DRC.

CONCLUSION

Despite challenges related to completeness of data reporting, meningitis dynamics shows weak seasonality in DRC. This tends to suggest that climatic, environmental factors might be less preponderant in shaping seasonal patterns in central Africa. The characterization of 8 distinct clusters of meningitis could be used for a better sentinel meningitis surveillance and optimization of vaccine strategy in DRC. Improving biological monitoring of suspected cases should be a priority for future eco-epidemiological studies to better understand the emergence and spread of meningitis pathogens, and the potential ecological, environmental drivers of this disease.

Recent changes in the epidemiology of Neisseria meningitidis serogroup W across the world, current vaccination policy choices and possible future strategies

Invasive meningococcal disease (IMD) is a serious disease that is fatal in 5–15% and disabling in 12–20% of cases. The dynamic and unpredictable epidemiology is a particular challenge of IMD prevention. Although vaccination against meningococcal serogroups A (MenA), MenC and, more recently, MenB, are proving successful, other serogroups are emerging as major IMD causes. Recently, surges in MenW incidence occurred in South America, Europe, Australia and parts of sub-Saharan Africa, with hypervirulent strains being associated with severe IMD and higher fatality rates. This review describes global trends in MenW-IMD epidemiology over the last 5–10 years, with emphasis on the response of national/regional health authorities to increased MenW prevalence in impacted areas. Several countries (Argentina, Australia, Chile, the Netherlands and UK) have implemented reactive vaccination campaigns to reduce MenW-IMD, using MenACWY conjugate vaccines. Future vaccination programs should consider the evolving epidemiology of MenW-IMD and the most impacted age groups.

Evidence for Rise in Meningococcal Serogroup C Bactericidal Antibody Titers in the Absence of Booster Vaccination in Previously Vaccinated Children

BACKGROUND

The introduction of meningococcal serogroup C (MenC) conjugate vaccines in the United Kingdom and Australia led to an impressive decline in the incidence of invasive disease. This study examined bactericidal antibody titers over time in the UK and Australian children who received a MenC conjugate vaccine in early childhood to test the hypothesis that ongoing boosting of immunity in the absence of further doses of vaccine in some children may contribute to ongoing protection from disease.

METHODS

Serum bactericidal assay using rabbit complement (rSBA) titers at each follow-up visit were compared with all preceding visits to identify any ≥4-fold rise in titers. The proportion of children with a ≥4-fold rise in rSBA titers in paired sera at any visit-to-visit comparison was calculated.

RESULTS

Of 392 children with at least one set of paired sera in the Australian cohort, 72 (18.4%) had a ≥4-fold increase in rSBA titers at least one year after vaccination, including six children (1.5%) who showed evidence of boosting twice. Of 234 children with at least one set of paired sera in the UK cohort, 39 (16.7%) had a ≥4-fold rise in rSBA titers at least one year after vaccination including 2 children (0.9%) with evidence of boosting twice.

CONCLUSIONS

A substantial minority of children immunized with MenC conjugate vaccine in early childhood had a rise in bactericidal antibody titers in the years after immunization in the absence of booster vaccination. This occurs most commonly at around 6-7 years of age corresponding to school entry and greater social mixing and might indicate exposure to MenC carriage.

Impact of meningococcal C conjugate vaccination programs with and without catch-up campaigns in adolescents: Lessons learned from Bahia, Brazil

The significant increase in the incidence rates and ongoing outbreaks of serogroup C meningococcal (MenC) disease, associated with the sequence type-103 complex, motivated the incorporation of the meningococcal C conjugate (MCC) vaccine in the routine immunization program in the State of Bahia, Brazil in early 2010, targeting children younger than 5 years of age. In its capital, Salvador, the program also included a catch-up campaign for individuals 10-24 years of age. We performed an observational, ecological study, analyzing data collected from 2007 to 2015, to compare the impact of these two immunization strategies on meningococcal disease incidence and mortality rates. In Salvador, following the vaccination program, a dramatic early impact on MenC disease and mortality rates could be observed, with significant reductions in incidence rates of MenC disease in all age groups, including individuals that were too old to have been vaccinated, indicating the presence of herd protection. Compared to the pre-vaccine period, a virtual disappearance of MenC disease was observed in 2015. However, in the state of Bahia (excluding the city of Salvador), no herd protection could be observed, with significant impact only among vaccine-eligible children within 5 years of introduction of the MCC vaccination program. These results highlight the importance of catch-up campaigns, including adolescents and young adults, to induce herd protection compared to immunization strategies restricted to infants and young children. This information is crucial for identifying optimal immunization policies and future strategies, focused on adolescents, to optimize the impact of MCC vaccination programs.

Knowing the scope of meningococcal disease in Latin America

Opportunities for strengthening surveillance of meningococcal disease exist between and within countries in Latin America. In August of 2015, a workshop was convened in the city of São Paulo, Brazil, to address the following objectives: 1) to review meningococcal disease burden and vaccine use in Latin America; 2) to evaluate the effectiveness of current meningococcal surveillance practices in the region; 3) to identify challenges to meningococcal surveillance in the region; and 4) to outline steps for strengthening meningococcal surveillance and disease control in the region. Based on the workshop’s discussions, recommendations for strengthening surveillance and controlling meningococcal disease in Latin America focus on improving: a) laboratory capabilities for diagnostic testing; b) communication regarding epidemiologic- and laboratory-based analyses; c) communication during outbreaks; d) monitoring of long-term disease outcomes; e) knowledge of vaccines against serogroup B disease; and f) criteria for defining and controlling meningococcal outbreaks. Overall, improving surveillance will help guide strategies for meningococcal disease prevention and control in Latin America.

Invasive meningococcal disease in the Veneto region of Italy: a capture-recapture analysis for assessing the effectiveness of an integrated surveillance system

BACKGROUND

Epidemiology of Neisseria meningitidis has been changing since the introduction of universal vaccination programmes against meningococcal serogroup C (MenC) and meningococcal serogroup B (MenB) has now become dominant. This study aimed to analyse the cases reported in institutional data recording systems to estimate the burden of invasive meningococcal diseases (IMDs) and assess the effectiveness of surveillance in Veneto region (Italy).

METHODS

Analysis was performed from 2007 to 2014 on data recorded in different systems: Mandatory Notification System, National Surveillance of Invasive Bacterial Diseases System and Laboratories Surveillance System (LSS), which were pooled into a combined surveillance system (CSS) and hospital discharge records (HDRs). A capture-recapture method was used and completeness of each source estimated. Number of cases with IMD by source of information and year, incidence of IMD by age group, case fatality rate (CFR) and distribution of meningococcal serogroups by year were also analysed.

RESULTS

Combining the four data systems enabled the identification of 179 confirmed cases with IMD, achieving an overall sensitivity of 94.7% (95% CI: 90.8% to 98.8%), while it was 76.7% (95% CI: 73.6% to 80.1%) for CSS and 77.2% (95% CI: 74.1% to 80.6%) for HDRs. Typing of isolates was done in 80% of cases, and 95.2% of the typed cases were provided by LSS. Serogroup B was confirmed in 50.3% of cases. The estimated IMD notification rate (cases with IMD diagnosed and reported to the surveillance systems) was 0.48/100 000 population, and incidence peaked at 6.2/100 000 in children aged <1 year old (60.9% due to MenB), and increased slightly in the age group between 15 and 19 years (1.1/100 000). A CFR of 14% was recorded (8.7% in paediatric age).

CONCLUSIONS

Quality of surveillance systems relies on case ascertainment based on serological characterisation of the circulating strains by microbiology laboratories. All available sources should be routinely combined to improve the epidemiology of IMD and the information used by public health departments to conduct timely preventive measures.

Of the Phrensy: an update on the epidemiology and pathogenesis of bacterial meningitis in the pediatric population

In the past century, advances in antibiotics and vaccination have dramatically altered the incidence and clinical outcomes of bacterial meningitis. We review the shifting epidemiology of meningitis in children, including after the implementation of vaccines that target common meningitic pathogens and the introduction of intrapartum antibiotic prophylaxis offered to mothers colonized with Streptococcus agalactiae. We also discuss what is currently known about the pathogenesis of meningitis. Recent studies of the human microbiome have illustrated dynamic relationships of bacterial and viral populations with the host, which may potentiate the risk of bacterial meningitis.

Meningococcal Carriage among Adolescents after Mass Meningococcal C Conjugate Vaccination Campaigns in Salvador, Brazil

Neisseria meningitidis is a commensal bacterium of the human nasopharynx. In rare cases, it penetrates the mucosa, entering the blood stream and causing various forms of disease. Meningococcal conjugate vaccines can prevent invasive disease not only by direct effect in vaccinated individuals but also by herd protection, preventing acquisition of carriage, which interrupts transmission and leads to protection of unvaccinated persons. In 2010 in Salvador, Brazil, an outbreak of group C meningococcal disease led to a mass meningococcal serogroup C conjugate vaccination drive, targeting those <5 and 10–24 years of age. The present study aimed to estimate the prevalence of and identify factors associated with N. meningitidis carriage among adolescents from Salvador, Brazil, in the post-vaccination period. In spring 2014, we performed a cross-sectional study involving 1,200 public school students aged 11–19 years old. Oropharyngeal swabs were collected to identify N. meningitidis. Of the 59 colonized participants, 36 (61.0%) carried non-groupable N. meningitidis, while genogroup B (11.9%), Y (8.5%), E (6.8%), Z (5.1%), C (3.4%), and W (3.4%) were also detected. The overall prevalence of N. meningitidis carriage was 4.9% (95% confidence interval [CI], 3.6–6.1%); the prevalence of N. meningitidis genogroup C was 0.17% (95% CI, 0.0–0.40%). There was no difference by age. Factors associated with carriage were having only one, shared, bedroom in the household (PR, 2.02; 95% CI, 0.99–4.12, p = 0.05); the mother being the only smoker in the home (PR, 2.48; 95% CI, 1.16–5.29; p = 0.01); and going to pubs/parties more than 5 times/month (PR, 2.61; 95% CI, 1.38–4.92; p = 0.02). Our findings show that the N. meningitidis carriage rate in adolescents from Salvador, Bahia, is low and is potentially influenced by the low prevalence of N. meningitidis genogroup C. However, continued surveillance is important to identify changes in the dynamics of N. meningitidis, including the emergence of diseases due to a non-C serogroup.

Immunoinformatics Approach in Designing Epitope-based Vaccine Against Meningitis-inducing Bacteria (Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae Type b)

Meningitis infection is one of the major threats during Hajj season in Mecca. Meningitis vaccines are available, but their uses are limited in some countries due to religious reasons. Furthermore, they only give protection to certain serogroups, not to all types of meningitis-inducing bacteria. Recently, research on epitope-based vaccines has been developed intensively. Such vaccines have potential advantages over conventional vaccines in that they are safer to use and well responded to the antibody. In this study, we developed epitope-based vaccine candidates against various meningitis-inducing bacteria, including Streptococcus pneumoniae, Neisseria meningitidis, and Haemophilus influenzae type b. The epitopes were selected from their protein of polysaccharide capsule. B-cell epitopes were predicted by using BCPred, while T-cell epitope for major histocompatibility complex (MHC) class I was predicted using PAProC, TAPPred, and Immune Epitope Database. Immune Epitope Database was also used to predict T-cell epitope for MHC class II. Population coverage and molecular docking simulation were predicted against previously generated epitope vaccine candidates. The best candidates for MHC class I- and class II-restricted T-cell epitopes were MQYGDKTTF, MKEQNTLEI, ECTEGEPDY, DLSIVVPIY, YPMAMMWRNASNRAI, TLQMTLLGIVPNLNK, ETSLHHIPGISNYFI, and SLLYILEKNAEMEFD, which showed 80% population coverage. The complexes of class I T-cell epitopes–HLA-C*03:03 and class II T-cell epitopes–HLA-DRB1*11:01 showed better affinity than standards as evaluated from their ΔGbinding value and the binding interaction between epitopes and HLA molecules. These peptide constructs may further be undergone in vitro and in vivo testings for the development of targeted vaccine against meningitis infection.

Carriage rate and effects of vaccination after outbreaks of serogroup C meningococcal disease, Brazil, 2010

Polysaccharide vaccine did not affect carriage nor interrupt transmission of an epidemic strain.

During 2010, outbreaks of serogroup C meningococcal (MenC) disease occurred in 2 oil refineries in São Paulo State, Brazil, leading to mass vaccination of employees at 1 refinery with a meningococcal polysaccharide A/C vaccine. A cross-sectional study was conducted to assess the prevalence of meningococci carriage among workers at both refineries and to investigate the effect of vaccination on and the risk factors for pharyngeal carriage of meningococci. Among the vaccinated and nonvaccinated workers, rates of overall meningococci carriage (21.4% and 21.6%, respectively) and of MenC carriage (6.3% and 4.9%, respectively) were similar. However, a MenC strain belonging to the sequence type103 complex predominated and was responsible for the increased incidence of meningococcal disease in Brazil. A low education level was associated with higher risk of meningococci carriage. Polysaccharide vaccination did not affect carriage or interrupt transmission of the epidemic strain. These findings will help inform future vaccination strategies.

The impact of the meningococcal serogroup C conjugate vaccine in Canada between 2002 and 2012

BACKGROUND

Before 2001, the incidence of invasive meningococcal disease (IMD) in Canada was 1.0 per 100 000 per year, with 40% of cases caused by serogroup C organisms. During 2001-2005 all provinces introduced the meningococcal serogroup C conjugate vaccine (MCCV) into their routine infant immunization schedule.

METHODS

Active, prospective, population-based surveillance of IMD in children and adults was conducted by the Canadian Immunization Monitoring Program, ACTive (IMPACT) during 2002-2012. Inclusion criteria were admission to hospital and identification of Neisseria meningitidis from a sterile site. Incidence was estimated using population census data from Statistics Canada.

RESULTS

Prior to MCCV introduction, serogroup C disease incidence was 0.07-0.25 per 100 000 per year depending on the province. Following vaccine introduction, serogroup C disease decreased to <0.05 per 100 000 per year, with a reduction of 14% per year (P = .0014). A decrease occurred in all provinces, despite differing schedules being implemented. The largest decrease of 83% (from 0.27 to 0.05 per 100 000 per year) occurred in the 15-24 year age group (P = .0100) who were not vaccinated in all provinces. There was no impact on the incidence of nonserogroup C disease over the same period (P = .9811).

CONCLUSIONS

MCCV dramatically reduced the incidence of serogroup C IMD in Canada through both direct and indirect effects. The observation that disease incidence decreased with different schedules suggests that the doses at 12 months (common to all provinces) and adolescence (7 of 8 provinces studied) were critical in achieving disease control.

A consensus statement: meningococcal disease among infants, children and adolescents in Latin America

Invasive meningococcal disease is a serious infection that occurs worldwide. Neisseria meningitidis remains one of the leading causes of bacterial meningitis in all ages. Despite the availability of safe and effective vaccines against invasive meningococcal disease, few countries in Latin America implemented routine immunization programs with these vaccines. The Americas Health Foundation along with Fighting Infectious Disease in Emerging Countries recently sponsored a consensus conference. Six experts in infectious diseases from across the region addressed questions related to this topic and formulated the following recommendations: (1) standardized passive and active surveillance systems should be developed and carriage studies are mandatory; (2) a better understanding of the incidence, case fatality rates and prevalent serogroups in Latin America is needed; (3) countries should make greater use of the polymerase chain reaction assays to improve the sensitivity of diagnosis and surveillance of invasive meningococcal disease; (4) vaccines with broader coverage and more immunogenicity are desirable in young infants; (5) prevention strategies should include immunization of young infants and catch-up children and adolescents and (6) because of the crowded infant immunization schedule, the development of combined meningococcal vaccines and the coadministration with other infant vaccines should be explored.

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

AIM

The aim of this study was to assess changes in trends of meningococcal disease and strain diversity of Neisseria meningitidis in Europe, South America, and Africa over the last 100 years.

METHODS

Healthcare databases and sources of grey literature were searched in 2012 and records were screened against the protocol eligibility criteria using a three-stage sifting process. Studies included in the review were subject to data extraction. Results were summarised using a narrative approach.

RESULTS

Serogroup A was the dominant cause of invasive meningococcal disease in Europe before and during World Wars I and II. Whilst serogroup B has been dominant from the 1970s in Europe and the 1980s in South America, outbreaks have emerged associated with serogroups W135 and Y in the twenty-first century. There has been a shift in the age groups affected by invasive meningococcal disease with an increase in incidence among the elderly associated with serogroup Y and a decline in serogroup C among adolescent populations. Recent outbreaks of serogroup W135 have occurred in some countries in South America. The epidemiological trend of invasive meningococcal disease has remained largely static across Africa and dominated by serogroup A although recently serogroups X and W135 have accounted for a large proportion of morbidity and mortality.

CONCLUSION

The epidemiology of N. meningitidis has been dynamic in Europe and South America especially over the last 30 years. Routine vaccination with serogroup C vaccines has led to reduced carriage and incidence of invasive meningococcal disease and herd immunity.

The current situation of meningococcal disease in Latin America and recommendations for a new case definition from the Global Meningococcal Initiative

The Global Meningococcal Initiative (GMI) is an international group of scientists and clinicians with expertise in meningococcal disease (MD). It promotes MD prevention through education and research. Given geographic differences in disease epidemiology, prevention strategies (e.g., vaccination) should be country-specific to ensure local needs are met. However, regional policies/recommendations and standardized disease diagnostic criteria should be implemented to improve surveillance and control strategies, and allow for more robust data comparisons. Consequently, the GMI convened a meeting with Latin American representatives to discuss the burden of MD and vaccination practices/policies, and consider if the global GMI recommendations could be tailored. The group determined that as robust, uniform epidemiologic data are required to make informed health-policy decisions, it would be useful to first summarize the regional situation herein (including disease surveillance, case definitions, epidemiology, vaccination and outbreak control strategies) and then determine a consensus-based meningococcal case definition for use throughout the region.

The K1 capsular polysaccharide from Acinetobacter baumannii is a potential therapeutic target via passive immunization

The emergence of extremely resistant and panresistant Gram-negative bacilli, such as Acinetobacter baumannii, requires consideration of nonantimicrobial therapeutic approaches. The goal of this report was to evaluate the K1 capsular polysaccharide from A. baumannii as a passive immunization target. Its structure was determined by a combination of mass spectrometric and nuclear magnetic resonance (NMR) techniques. Molecular mimics that might raise the concern for autoimmune disease were not identified. Immunization of CD1 mice demonstrated that the K1 capsule is immunogenic. The monoclonal antibody (MAb) 13D6, which is directed against the K1 capsule from A. baumannii, was used to determine the seroprevalence of the K1 capsule in a collection of 100 A. baumannii strains. Thirteen percent of the A. baumannii isolates from this collection were seroreactive to MAb 13D6. Opsonization of K1-positive strains, but not K1-negative strains, with MAb 13D6 significantly increased neutrophil-mediated bactericidal activity in vitro (P < 0.05). Lastly, treatment with MAb 13D6 3 and 24 h after bacterial challenge in a rat soft tissue infection model resulted in a significant decrease in the growth/survival of a K1-positive strain compared to that of a K1-negative strain or to treatment with a vehicle control (P < 0.0001). These data support the proof of principle that the K1 capsule is a potential therapeutic target via passive immunization. Other serotypes require assessment, and pragmatic challenges exist, such as the need to serotype infecting strains and utilize serotype-specific therapy. Nonetheless, this approach may become an important therapeutic option with increasing antimicrobial resistance and a diminishing number of active antimicrobials.

Identification and proposal of a potentially new clonal complex that is a common cause of MenB disease in Central and Eastern Canada

This study examined serogroup B meningococci (MenB) from invasive meningococcal disease (IMD) cases in the provinces of Québec and Ontario in the last decade by multilocus sequence typing (MLST) to determine their sequence types (STs) and clonal complexes (CCs). Forty isolates from individual MenB IMD cases were found to belong to 8 related STs, with ST-336 being the founding ST and the other 7 STs being single locus variants of ST-336. Eleven isolates belonged to ST-336, 23 belonged to ST-5571, and the other 6 were represented individually by a single different ST. All but 1 of these 40 isolates have the PorA variable-region type of P1.22,14,36. Interrogation of the Neisseria MLST web site with the present finding did not put any of the 8 related STs into known CCs. Since these 8 related STs were common causes of IMD, with ST-5571 being the most frequently identified ST in Ontario and ST-336 the third most common ST identified in Québec, we propose that ST-336 and its related STs is a potentially new meningococcal clonal complex that is endemic in the Canadian provinces of Québec and Ontario, and they constitute a common cause of IMD.

Meningococcal serogroup Y emergence in Europe: update 2011

Neisseria meningitidis is differentiated into 12 distinct serogroups, of which A, B, C, W-135, X, and Y are medically most important and represent an important health problem in different parts of the world. The epidemiology of N. meningitidis is unpredictable over time and across geographic regions. Recent epidemiological surveillance has indicated an increase of serogroup Y invasive meningococcal disease in some parts of Europe as shown in the epidemiological data for 2010 from various European countries previously published in this journal. ( 1) Here, data is reported indicating that the emergence of serogroup Y continued in 2011 in various regions of Europe. The average age of persons affected by N. meningitidis serogroup Y seems to have decreased in some countries in comparison to the previous decade.

Considerations for controlling invasive meningococcal disease in high income countries

The development of conjugate vaccines has enabled the prevention and control of Neisseria meningitidis caused by serogroups A, C, W-135 and Y. Vaccines that provide protection against a broad number of serogroup B strains likely will be available soon to enable greater control of meningococcal disease in high income countries. We present an argument for adequate post-marketing surveillance to monitor epidemiological shifts and to provide a context for the safety and reactogenicity of serogroup B vaccines, including the newer recombinant vaccines. We also offer a series of recommendations to address possible concerns about vaccine safety.

[Anti-meningococcal vaccines: diversity of vaccination policies and recommendations]

In European Country, Canada, Australia and Brazil immunization program with conjugate meningococcal C, including universal vaccination of infants or toddlers, with a catch-up program up to 19 y in several areas, have been successful in reducing disease incidence through direct and indirect protection. In USA, quadrivalent conjugate vaccines targeting serogroups ACYW135 are used in programs of adolescent immunization at 10 and 15 years because serotype Y is frequent. A mass immunization campaign against serogroupe A disease with a conjugate vaccine is beginning in African belt of meningitis. Polysaccharide vaccines A, C or ACYW135 are used in travelers but quadrivalent conjugate vaccine, with larger targets, gives higher titers after booster and must be preferred. Some questions are pending: immunize before or after one year of age, a booster dose in adolescence and the routine use of quadrivalent conjugate vaccine in Europe if the incidence of serotype Y is growing.

Importance of circulating antibodies in protection against meningococcal disease

Neisseria meningitidis infection results in life-threatening illnesses, including bacteremia, sepsis and meningitis. Early diagnosis and treatment are a challenge due to rapid disease progression, resulting in high mortality and morbidity in survivors. Disease can occur in healthy individuals, however, risk of infection is higher in patients with certain risk factors. N meningitidis carriage and case-fatality rates are high in adolescents and young adults. The absolute incidence of meningococcal disease has decreased partially due to increasing meningococcal vaccination rates. Maintaining protective levels of circulating antibodies by vaccination is necessary for clinical protection against disease. The Centers for Disease Control and Prevention Advisory Committee on Immunization Practices guidelines recommend vaccination for all individuals aged 11 through 12 years, followed by a booster dose at age 16 years for maintenance of protective antibody levels throughout the high-risk years. Despite these guidelines, many adolescents remain unvaccinated and susceptible to infection and disease.