Invasive meningococcal disease in Quebec, Canada, due to an emerging clone of ST-269 serogroup B meningococci with serotype antigen 17 and serosubtype antigen P1.19 (B:17:P1.19)

Temporal variations in the serogroup distribution of invasive meningococcal disease in Quebec, Canada, due to emerging unique clade of serogroup Y strain belonging to the Sequence Type-23 clonal complex

OBJECTIVE

To identify recent trends in invasive meningococcal diseases (IMD) in Quebec, Canada, with a focus on MenY cases and MenY strains.

METHODS

IMD cases and MenY strains from January 1, 2015 to August 11, 2023 were analyzed for clonal analysis and prediction of susceptibility to MenB vaccines. MenY strains of ST-23 CC from Quebec were analyzed with global MenY strains by core-genomic multi-locus sequence typing (cg-MLST).

RESULTS

Since 2015 the serogroup distribution of IMD in Quebec has shifted from predominantly MenB to mainly MenY, with most (80.9 %) of the latter belonging to ST-23 CC. The median age of MenY cases due to ST-23 CC were statistically younger than MenY cases due to non-ST-23 CC. MenY of ST-23 CC showed genetic diversity and the major genetic cluster were similar to the Swedish Y1 strain. The increase in invasive MenY disease in Quebec was due to a sub-clade of Lineage 23.1 which caused an elevated proportion of severe disease in young adults.

CONCLUSION

The increase in invasive MenY disease in Quebec, Canada was driven by the expansion of a sub-clade of Lineage 23.1 in young adults. Currently available quadrivalent A,C,W,Y-conjugate meningococcal vaccines were predicted to provide protection against these strains.

Characterization of invasive meningococcal disease case isolates in Atlantic Canada, 2014 to 2020: spatial-temporal variations of clones and predicted meningococcal B vaccine coverage

Introduction. Invasive meningococcal disease (IMD) caused by Neisseria meningitidis may show temporal and geographical changes in both the epidemiology and the characteristics of the strains involved.Gap statement. A study that examined invasive N. meningitidis causing IMD in Atlantic Canada from 2009 to 2013 was published in 2014. Data from subsequent years have not been described.Aim. This study examined the molecular epidemiology of IMD in four Atlantic Provinces of Canada as well as potential serogroup B (MenB) vaccine coverage.Methods. Individual IMD case isolates recovered from 2014 to 2020 were analysed for serotype and serosubtype antigens as well as by whole-genome sequencing (WGS) for prediction of potential MenB vaccine coverage.Results. Of the 56 IMD isolates, 42, 8, 5 and 1 were MenB, serogroup Y, serogroup W (MenW) and serogroup C, respectively. Geographical differences in the distribution of MenB clones revealed concentration of sequence type (ST)-269 clonal complex (cc) and ST-60 cc in Newfoundland and Labrador, while ST-41/44 cc (particularly ST-154) was predominantly found in New Brunswick and Nova Scotia. Core genome multi-locus sequence typing (cgMLST) also separated the New Brunswick and Nova Scotia ST-154 isolates into two clusters, with differences in their nhba and penA alleles. Furthermore, cgMLST also separated the ST-269 cc isolates in Atlantic Canada into the ST-1611 and the ST-269/ST-8924 clusters, with the latter showing high similarity to the ST-269 that first emerged in the Province of Quebec. Genetic Meningococcal Antigen Typing System showed that 54.8 % of MenB were predicted to be covered by the MenB vaccine Bexsero, with a further 38.1 % potentially covered by virtue of the presence of genes that encoded factor H-binding protein variant 1 proteins. Meningococcal deduced vaccine antigen reactivity predicted from WGS data showed that 95.3 % of MenB were covered by Trumenba. Four cases of IMD due to MenW ST-11 cc were also identified, with the first case found in 2018.Conclusions. This study provided evidence concerning the dynamics of N. meningitidis strains causing IMD in Atlantic Canada, with both geographical and temporal differences found. MenB vaccine appeared to provide good coverage of MenB IMD, especially towards the predominant strain of ST-154.

A Narrative Review of the Molecular Epidemiology and Laboratory Surveillance of Vaccine Preventable Bacterial Meningitis Agents: Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae and Streptococcus agalactiae

This narrative review describes the public health importance of four most common bacterial meningitis agents, Streptococcus pneumoniae, Neisseria meningitidis, Haemophilus influenzae, and S. agalactiae (group B Streptococcus). Three of them are strict human pathogens that normally colonize the nasopharynx and may invade the blood stream to cause systemic infections and meningitis. S. agalactiae colonizes the genito-gastrointestinal tract and is an important meningitis agent in newborns, but also causes invasive infections in infants or adults. These four bacteria have polysaccharide capsules that protect them against the host complement defense. Currently licensed conjugate vaccines (against S. pneumoniae, H. influenza, and N. meningitidis only but not S. agalactiae) can induce protective serum antibodies in infants as young as two months old offering protection to the most vulnerable groups, and the ability to eliminate carriage of homologous serotype strains in vaccinated subjects lending further protection to those not vaccinated through herd immunity. However, the serotype-specific nature of these vaccines have driven the bacteria to adapt by mechanisms that affect the capsule antigens through either capsule switching or capsule replacement in addition to the possibility of unmasking of strains or serotypes not covered by the vaccines. The post-vaccine molecular epidemiology of vaccine-preventable bacterial meningitis is discussed based on findings obtained with newer genomic laboratory surveillance methods.

The everchanging epidemiology of meningococcal disease worldwide and the potential for prevention through vaccination

Neisseria meningitidis is a major cause of bacterial meningitis and septicaemia worldwide and is associated with high case fatality rates and serious life-long complications among survivors. Twelve serogroups are recognised, of which six (A, B, C, W, X and Y) are responsible for nearly all cases of invasive meningococcal disease (IMD). The incidence of IMD and responsible serogroups vary widely both geographically and over time. For the first time, effective vaccines against all these serogroups are available or nearing licensure. Over the past two decades, IMD incidence has been declining across most parts of the world through a combination of successful meningococcal immunisation programmes and secular trends. The introduction of meningococcal C conjugate vaccines in the early 2000s was associated with rapid declines in meningococcal C disease, whilst implementation of a meningococcal A conjugate vaccine across the African meningitis belt led to near-elimination of meningococcal A disease. Consequently, other serogroups have become more important causes of IMD. In particular, the emergence of a hypervirulent meningococcal group W clone has led many countries to shift from monovalent meningococcal C to quadrivalent ACWY conjugate vaccines in their national immunisation programmes. Additionally, the recent licensure of two protein-based, broad-spectrum meningococcal B vaccines finally provides protection against the most common group responsible for childhood IMD across Europe and Australia. This review describes global IMD epidemiology across each continent and trends over time, the serogroups responsible for IMD, the impact of meningococcal immunisation programmes and future needs to eliminate this devastating disease.

Persistence of the immune response after 4CMenB vaccination, and the response to an additional booster dose in infants, children, adolescents, and young adults

The multicomponent meningococcal serogroup B vaccine, 4CMenB, has demonstrated effectiveness in preventing invasive MenB disease in infants and in controlling MenB outbreaks. The need for/timing of additional booster doses is not yet established. We reviewed eight studies that evaluated antibody persistence and booster following primary 4CMenB vaccination of infants, children, adolescents, and young adults. Putative seroprotective hSBA titers for ≥1 vaccine antigen were maintained by 76-100% of children 24-36 months after priming during infancy and in 84-100% after priming in the second year of life. hSBA levels were higher in vaccinees at 4 and 7.5 years following priming during adolescence than in vaccine-naïve individuals of a similar age. Antibodies persisted at higher levels to NHBA and NadA than to PorA or fHbp. Booster vaccination induced robust anamnestic responses, demonstrating effective priming by 4CMenB across age-groups. These data can inform decision-making to optimize vaccination strategies.

Impact of a mass vaccination campaign against Serogroup B meningococcal disease in the Saguenay-Lac-Saint-Jean region of Quebec four years after its launch

In the Saguenay-Lac-Saint-Jean region of Quebec, 83% of the population ≤20 years (n ≅ 59,500) was immunized in 2014 with the four-component Serogroup B meningococcal vaccine to control a long-lasting outbreak caused by a virulent ST-269 Serogroup B Neisseria meningitidis clone. Following the campaign, invasive meningococcal B disease (B-IMD) incidence fell sharply in the target population from 11.4/100,000 in 2006-2014 to 0.4/100,000 in 2014-2018 (p < 0.0001). Five B-IMD cases occurred in the region from July 2014 to June 2018, including one vaccinated child, one unvaccinated young adult and 3 unvaccinated elderly adults. Estimate of direct vaccine protection was 79% [95%CI:-231%;99%]. The overall campaign impact in the region taking into account the decrease in B-IMD incidence at provincial level was a 86% [95%CI:-2%;98%] decrease in B-IMD risk. The campaign impact was mostly seen in the target age-group suggesting no herd effect among unvaccinated older adults.

Optimizing the timing of 4CMenB vaccination in adolescents and young adults based on immune persistence and booster response data

INTRODUCTION

Meningococcal disease has an incidence peak spread over several years during adolescence and young adulthood in the United States. Meningococcal serogroup B (MenB) vaccines have been introduced relatively recently and may help protect individuals in these age groups. Currently there is insufficient long-term experience to determine the duration of disease protection after any MenB vaccine. Understanding antibody persistence after primary vaccination and responses to booster can help inform MenB vaccination strategies and optimize disease prevention. Areas covered: Four studies in adolescents/young adults vaccinated with meningococcal B vaccine 4CMenB were reviewed with the aim to compare findings across studies and draw key learnings. The studies varied by geographic location, population characteristics, and timing of antibody measurement relative to primary vaccination. Expert opinion: Antibody persistence data for 4CMenB are substantial, extending 7.5 years post-primary vaccination. Vaccination at age 16-18 years may help protect adolescents throughout their highest age-based risk period. Similar robust responses to a single booster dose were observed 4 and 7.5 years after primary vaccination. In outbreak settings it is beneficial to have received prior vaccination; residual circulating antibodies may provide protection, and a single dose induces booster responses within 7 days, which is quicker than administration of a 2-dose series to vaccine-naïve individuals.

A Meningococcal Native Outer Membrane Vesicle Vaccine With Attenuated Endotoxin and Overexpressed Factor H Binding Protein Elicits Gonococcal Bactericidal Antibodies

BACKGROUND

Meningococcal outer membrane vesicle (OMV) vaccines are prepared with detergents to remove endotoxin, which also remove desirable antigens such as factor H binding protein (FHbp). Native OMV (NOMV) vaccines with genetically attenuated endotoxin do not require detergent treatment and elicit broader serum bactericidal antibody (SBA) responses than OMV or recombinant FHbp (rFHbp) vaccines.

METHODS

We measured human complement-mediated SBA responses in mice immunized with NOMV with overexpressed FHbp subfamily B (NOMV-FHbp), NOMV with FHbp genetically inactivated (NOMV-KO), and/or a control rFHbp vaccine against meningococcal and gonococcal strains.

RESULTS

Despite having 36-fold less FHbp per dose, the NOMV-FHbp vaccine elicited a ≥3-fold higher serum IgG anti-FHbp geometric mean titer than control vaccines containing rFHbp (P ≤ .003). Against 2 meningococcal outbreak strains with mismatched PorA and heterologous FHbp subfamily B sequence variants, the NOMV-FHbp vaccine produced ≥30-fold higher SBA titers than control vaccines. Mice immunized with NOMV-FHbp and NOMV-KO vaccines also elicited SBA against a gonococcal strain (P < .0001 vs the adjuvant-only control group). In contrast, 2 licensed meningococcal serogroup B vaccines, including one containing detergent-extracted OMV, did not produce gonococcal SBA in humans.

CONCLUSIONS

A meningococcal NOMV vaccine elicits SBA against gonococci and with overexpressed FHbp elicits SBA against meningococci.

Impact of an Immunization Campaign to Control an Increased Incidence of Serogroup B Meningococcal Disease in One Region of Quebec, Canada

Background

Invasive meningococcal disease (IMD) incidence increased in Quebec, starting in 2003, and was caused by a serogroup B sequence type 269 clone. The Saguenay-Lac-Saint-Jean (SLSJ) region was particularly affected with a rate of 3.4 per 100000 person-years in 2006-2013. In May 2014, an immunization campaign was launched in SLSJ, using the 4-component protein-based meningococcal vaccine (MenB-4C). We aimed to evaluate the impact of the campaign 2 years after its initiation.

Methods

Immunization registry data and serogroup B invasive meningococcal disease (B-IMD) cases notified to public health authorities and confirmed by culture or polymerase chain reaction from July 1996 to December 2016 were analyzed, including a multivariate Poisson regression model of incidence rates.

Results

By the end of the campaign, 82% of the 59000 targeted SLSJ residents between 2 months and 20 years of age had been immunized. Following the initiation of the campaign, no B-IMD case occurred among vaccinees, whereas 2 cases were reported among unvaccinated adult SLSJ residents, and a third case in an unvaccinated child who had stayed in the region during the week prior to disease onset, in 2015. B-IMD incidence decreased in all other regions in the years 2015-2016 but sporadic cases continued to occur. A multivariate analysis showed a significant effect of the campaign in the SLSJ region (relative B-IMD risk: 0.22; P = .04).

Conclusions

Results suggest a high level of protection provided by MenB-4C following mass vaccination at regional level. This, along with reassuring safety data, supports the current recommendations for MenB-4C use for controlling outbreaks caused by clones covered by the vaccine.

Characterization of Oropharyngeal Carriage Isolates of Neisseria meningitidis in Healthy Korean Adolescents in 2015

The meningococcus carriage rate is age-dependent, with a high prevalence in adolescents and young adults. This cross-sectional study aimed to estimate the oropharyngeal carriage rate of meningococcus among healthy Korean adolescents and its relationship with several population characteristics. The survey was conducted from April to May 2015 among 1,460 first-year high-school students in 9 high schools located in Gyeonggi province, Korea. Each student answered a short questionnaire assessing risk factors for carriage, and posterior pharyngeal wall swab samples were obtained. These samples were cultured on meningococcus-selective media, with colonies resembling meningococci identified using the Vitek® MS system (bioMérieux, Marcy l'Etoile, France). All isolates were characterized by molecular serogrouping and multilocus sequence typing (MLST). Meningococci were identified from 3.4% (49/1,460) swabs. Current smokers had significantly higher carriage rates than non-smokers (8.2% vs. 2.9%, P = 0.002), and boys had significantly higher carriage rates than girls (4.4% vs. 1.6%, P = 0.004). Serogroup B was the most common serogroup, followed by serogroup C, then 29E and Y. Twenty-seven different sequence types (STs) were identified; the most common were ST-3091, ST-11278, and ST-44. These belonged to clonal complexes (CCs) 269, 32, and 41/44, respectively, known as the hypervirulent clones. Evaluating meningococcal carriage is important to understand the epidemiology of meningococcal disease; however, little data exist in Korea. Similar to western countries, meningococcal serogroup B has emerged in Korea, and hypervirulent clones were identified. It is necessary to monitor the genetic and serologic characteristics of circulating meningococci and to assess the potential strain coverage of meningococcal vaccines.

Characterization of invasive Neisseria meningitidis from Atlantic Canada, 2009 to 2013: With special reference to the nonpolysaccharide vaccine targets (PorA, factor H binding protein, Neisseria heparin-binding antigen and Neisseria adhesin A)

BACKGROUND

Serogroup B Neisseria meningitidis (MenB) has always been a major cause of invasive meningococcal disease (IMD) in Canada. With the successful implementation of a meningitis C conjugate vaccine, the majority of IMD in Canada is now caused by MenB.

OBJECTIVE

To investigate IMD case isolates in Atlantic Canada from 2009 to 2013. Data were analyzed to determine the potential coverage of the newly licensed MenB vaccine.

METHODS

Serogroup, serotype and serosubtype antigens were determined from IMD case isolates. Clonal analysis was performed using multilocus sequence typing. The protein-based vaccine antigen genes were sequenced and the predicted peptides were investigated.

RESULTS

The majority of the IMD isolates were MenB (82.5%, 33 of 40) and, in particular, sequence type (ST)-154 B:4:P1.4 was responsible for 47.5% (19 of 40) of all IMD case isolates in Atlantic Canada. Isolates of this clone expressed the PorA antigen P1.4 and possessed the nhba genes encoding for Neisseria heparin-binding antigen peptide 2, which together matched exactly with two of the four components of the new four-component meningococcal B vaccine. Nineteen MenB isolates had two antigenic matches, another five MenB and one meningitis Y isolate had one antigenic match. This provided 75.8% (25 of 33) potential coverage for MenB, or a 62.5% (25 of 40) overall potential coverage for IMD.

CONCLUSION

From 2009 to 2013, IMD in Atlantic Canada was mainly caused by MenB and, in particular, the B:4:P1.4 ST-154 clone, which accounted for 47.5% of all IMD case isolates. The new four-component meningococcal B vaccine appeared to offer adequate coverage against MenB in Atlantic Canada.

Characterization of invasive Neisseria meningitidis strains from Québec, Canada, during a period of increased serogroup B disease, 2009-2013: phenotyping and genotyping with special emphasis on the non-carbohydrate protein vaccine targets

BACKGROUND

The epidemiology of invasive meningococcal disease (IMD) in Québec, Canada, has been dominated in the past decade by a clone of serogroup B (MenB) Neisseria meningitidis defined by multi-locus sequence typing (MLST) as sequence type (ST)-269. With the licensure of a new MenB vaccine Bexsero (4CMenB) in Canada, this study characterized invasive N. meningitidis recovered in Québec from 2009 to 2013, with an objective to examine the diversity of the 4CMenB vaccine antigens. Isolates were serogrouped by antisera and genogrouped by PCR, and further typed by whole cell ELISA for serotype and serosubtype antigens. Clonal analysis was done by MLST. Isolates were genotyped by analysis of their 4CMenB vaccine antigen genes of PorA, factor H binding protein (fHbp), Neisserial Heparin Binding Antigen (NHBA), and Neisseria Adhesin A (NadA).

RESULTS

Of the 263 IMD isolates analysed, 229, 16, 10, 7, and 1 belonged to MenB, MenY, MenW, MenC, and MenX, respectively. Of the 229 MenB, 159 (69.4 %) were typed as ST-269 clonal complex (CC); and they possessed a restricted number of three fHbp and five nhba gene alleles. Nine N. meningitidis isolates (eight MenB and one MenY) were found to possess at least one gene that encoded for an antigen that matched exactly with protein variants in the 4CMenB vaccine. Two MenB expressed PorA antigen P1.4 and possessed the nhba gene for peptide 2; four other MenB were predicted to have NHBA peptide 2; another two MenB were predicted to encode fHbp peptide 1.1; and a single MenY was found to have nadA gene for NadA peptide 8. In addition, another 172 isolates were found to possess genes for variant 1 fHbp peptides other than peptide 1.1 or NadA variant 1-2/3 peptides other than peptide 8; and therefore, may potentially be covered by 4CMenB.

CONCLUSION

The most prevalent clone of N. meningitidis in Quebec was ST-269 CC; and 96 % of the isolates in this CC were predicted to be covered by 4CMenB vaccine. Extensive genetic diversity was found in the other IMD isolates in Québec which might suggest a lower coverage by the vaccine when compared to the ST-269 MenB.

Determination of serotyping antigens, clonal analysis and genetic characterization of the 4CMenB vaccine antigen genes in invasive Neisseria meningitidis from Western Canada, 2009 to 2013

This study examined invasive Neisseria meningitidis recovered from invasive meningococcal disease (IMD) cases in Western Canada between 2009 and 2013. A total of 161 isolates from individual IMD cases were analysed for serogroup, serotype, serosubtype, PorA genotype, multi-locus sequence type and nucleotide sequence of their 4CMenB vaccine antigen genes. Sixty-nine isolates were serogroup B (MenB), 47 were serogroup Y (MenY), 22 were serogroup C (MenC), 19 were serogroup W (MenW), three were serogroup E and one was non-encapsulated. MenC, MenY and MenW were mainly clonal, represented primarily by clonal complex (cc) 11, cc23 or cc167, and cc22, respectively. In contrast, MenB were composed of eight different ccs together with 11 isolates not assigned to any known cc. Antigenic analysis and PorA genotyping confirmed the heterogeneity of MenB isolates, while such results supported the clonal nature of most MenC, MenY and MenW isolates. Thirty-four (21.1%) isolates had at least one gene that encoded one matching vaccine protein component of the 4CMenB vaccine (i.e. PorA P1.4; fHbp variant 1.1; NHBA peptide 2; and NadA-1, -2, or -3). An additional 18 isolates had genes that encoded variant 1 or subfamily B factor H binding proteins of this same vaccine.

Enhanced surveillance of invasive meningococcal disease in Canada, 2006-2011

Objective

The purpose of this report is to describe the epidemiology of invasive meningococcal disease (IMD) in Canada from 2006 to 2011.

Methods

Data from the Enhanced Invasive Meningococcal Disease Surveillance System and national population estimates were selected for descriptive and inferential analyses. The geographic, demographic, seasonal and subtype distributions as well as clinical characteristics of the IMD cases were examined. Incidence and mortality rates were calculated per 100,000 population per year; 95% confidence intervals (CI) were calculated for rate comparison. The direct method was used for age standardization. Proportions were compared using the chi-squared test at a p<0.05 significance level.

Results

During the study period, the mean incidence rates of IMD were 0.58 (total), 0.33 (serogroup B), 0.07 (serogroup C), 0.03 (serogroup W-135) and 0.10 (serogroup Y). The median age for serogroups B, C, W-135 and Y was 16, 43, 38 and 47 years respectively. The mean age-specific incidence rates among infants under 1 year of age (7.35, CI: 5.38-9.32) and children from 1 to 4 years of age (1.89, CI: 1.54-2.24) were significantly higher than those in any other age group. The mean case fatality ratio was 8.1% (range 4.3%-14.3%). The average number of cases that occurred per month was significantly higher (p<0.0001) in winter (18 cases) than in summer (12 cases).

Conclusion

IMD is still endemic in Canada. Although individuals at any age can be affected, infants under 1 year of age are at the greatest risk, followed by children aged 1-4 years and individuals aged 15-19 years. Following the implementation of routine childhood immunization programs with monovalent meningococcal C conjugate vaccines (MenC) in all provinces and territories (beginning in 2007), the incidence of serogroup C has decreased significantly over the study period and is now at an all-time low. Serogroup B is the leading cause of IMD, and diseases of serogroup W-135 and Y have stabilized at relatively lower incidence rates. With the addition of immunization programs using quadrivalent conjugate meningococcal vaccines (MCV4), we would expect further reductions in the incidence of meningococcal infection in Canada.

Controlling serogroup B invasive meningococcal disease: the Canadian perspective

With publically funded meningococcal immunization programs established in infants, children and adolescents, Canada is at the forefront of invasive meningococcal disease prevention. The advent of two new serogroup B vaccines that may protect against multiple disease-causing strains offers the potential to reduce endemic disease to very low levels in Canada. Canada likely will be one of the first countries with approval to use recombinant serogroup B vaccine. However, inclusion of these new vaccines into public immunization programs will be decided at the provincial/territorial level, rather than nationally, and may result initially in different immunization schedules throughout the country as we have seen with conjugate meningococcal vaccines. Such heterogeneous use and adoption of new vaccines complicates disease control, but may assist in evaluation of effectiveness. Minimally, it requires regionally specific information. In this article, the authors provide an overview of the Canadian epidemiology, serogroup B vaccine characteristics, potential strain coverage, immunization strategies and remaining postmarketing research questions.

An analysis of the sequence variability of meningococcal fHbp, NadA and NHBA over a 50-year period in the Netherlands

Studies of meningococcal evolution and genetic population structure, including the long-term stability of non-random associations between variants of surface proteins, are essential for vaccine development. We analyzed the sequence variability of factor H-binding protein (fHbp), Neisserial Heparin-Binding Antigen (NHBA) and Neisseria adhesin A (NadA), three major antigens in the multicomponent meningococcal serogroup B vaccine 4CMenB. A panel of invasive isolates collected in the Netherlands over a period of 50 years was used. To our knowledge, this strain collection covers the longest time period of any collection available worldwide. Long-term persistence of several antigen sub/variants and of non-overlapping antigen sub/variant combinations was observed. Our data suggest that certain antigen sub/variants including those used in 4CMenB are conserved over time and promoted by selection.

Prolonged university outbreak of meningococcal disease associated with a serogroup B strain rarely seen in the United States

BACKGROUND

College students living in residential halls are at increased risk of meningococcal disease. Unlike that for serogroups prevented by quadrivalent meningococcal vaccines, public health response to outbreaks of serogroup B meningococcal disease is limited by lack of a US licensed vaccine.

METHODS

In March 2010, we investigated a prolonged outbreak of serogroup B disease associated with a university. In addition to case ascertainment, molecular typing of isolates was performed to characterize the outbreak. We conducted a matched case-control study to examine risk factors for serogroup B disease. Five controls per case, matched by college year, were randomly selected. Participants completed a risk factor questionnaire. Data were analyzed using conditional logistic regression.

RESULTS

Between January 2008 and November 2010, we identified 13 meningococcal disease cases (7 confirmed, 4 probable, and 2 suspected) involving 10 university students and 3 university-linked persons. One student died. Ten cases were determined to be serogroup B. Isolates from 6 confirmed cases had an indistinguishable pulsed-field gel electrophoresis pattern and belonged to sequence type 269, clonal complex 269. Factors significantly associated with disease were Greek society membership (matched odds ratio [mOR], 15.0; P = .03), >1 kissing partner (mOR, 13.66; P = .03), and attending bars (mOR, 8.06; P = .04).

CONCLUSIONS

The outbreak was associated with a novel serogroup B strain (CC269) and risk factors were indicative of increased social mixing. Control measures were appropriate but limited by lack of vaccine. Understanding serogroup B transmission in college and other settings will help inform use of serogroup B vaccines currently under consideration for licensure.

The changing epidemiology of meningococcal disease in North America 1945-2010

The epidemiology of Invasive Meningococcal Disease (IMD) is distinct in the United States and Canada compared with other countries. This review describes the incidence, mortality and vaccination strategies relevant to IMD in these countries over the past 65 y. The incidence of IMD has remained consistently low in both countries during this period. Serogroup B and serogroup C have been the most prominent disease-causing serogroups. Notably, serogroup Y has recently become an important cause of IMD in the USA, but has not been as prominent in Canada. Periodic rises in incidence have been characterized by local outbreaks that have raised public concern, especially those caused by serogroup C in Canada, and serogroup B in the USA. Case fatality rates have remained consistent at around 10-20%, but vary by age and serogroup. Recent outbreaks have led to the introduction of vaccination programs for both outbreak control and routine immunization.

The disease burden of invasive meningococcal serogroup B disease in Canada

BACKGROUND

Invasive meningococcal disease remains a rare but deadly infection in Canada. New serogroup B vaccines may offer the potential for prevention and control. This report examines the disease burden caused by serogroup B invasive meningococcal infections.

METHODS

From 2002 to 2011, active, population-based metropolitan area surveillance for adult and pediatric hospital admissions for adult and pediatric hospital admissions for laboratory-confirmed infection with Neisseria meningitidis, was conducted by the 12 centers of the Canadian Immunization Monitoring Program, Active.

RESULTS

A total of 769 invasive meningococcal cases occurred from 2002 to 2011; 54% (n = 413) in children with a peak incidence of 6.16 (95% confidence interval: 3.18-10.76) per 100,000 in children aged <1 year in 2009. Serogroup B accounted for the largest proportion of cases and had the highest incidence of all serogroups across all ages, with a peak incidence of 0.31 (0.23-0.40) per 100,000 in 2007. Serogroup B case fatality rate was 4.3% in children, and 21% of pediatric survivors had sequelae. B:17:P1.19 ST-269 was the most frequently detected antigenic type.

CONCLUSIONS

Serogroup B invasive meningococcal infections caused substantial morbidity and mortality and are the leading cause of invasive meningococcal disease in Canada. The proportion of cases potentially preventable with the new serogroup B vaccines should be evaluated to determine whether universal immunization programs are warranted.

The changing epidemiology of meningococcal disease in Quebec, Canada, 1991-2011: potential implications of emergence of new strains

Background

In order to inform meningococcal disease prevention strategies, we analysed the epidemiology of invasive meningococcal disease (IMD) in the province of Quebec, Canada, 10 years before and 10 years after the introduction of serogroup C conjugate vaccination.

Methodology

IMD cases reported to the provincial notifiable disease registry in 1991–2011 and isolates submitted for laboratory surveillance in 1997–2011 were analysed. Serogrouping, PCR testing and assignment of isolates to sequence types (ST) by using multilocus sequence typing (MLST) were performed.

Results

Yearly overall IMD incidence rates ranged from 2.2–2.3/100,000 in 1991–1992 to 0.49/100,000 in 1999–2000, increasing to 1.04/100,000 in 2011. Among the 945 IMD cases identified by laboratory surveillance in 1997–2011, 68%, 20%, 8%, and 3% were due to serogroups B, C, Y, and W135, respectively. Serogroup C IMD almost disappeared following the implementation of universal childhood immunization with monovalent C conjugate vaccines in 2002. Serogroup B has been responsible for 88% of all IMD cases and 61% of all IMD deaths over the last 3 years. The number and proportion of ST-269 clonal complex has been steadily increasing among the identified clonal complexes of serogroup B IMD since its first identification in 2003, representing 65% of serogroup B IMD in 2011. This clonal complex was first introduced in adolescent and young adults, then spread to other age groups.

Conclusion

Important changes in the epidemiology of IMD have been observed in Quebec during the last two decades. Serogroup C has been virtually eliminated. In recent years, most cases have been caused by the serogroup B ST-269 clonal complex. Although overall burden of IMD is low, the use of a vaccine with potential broad-spectrum coverage could further reduce the burden of disease. Acceptability, feasibility and cost-effectiveness studies coupled with ongoing clinical and molecular surveillance are necessary in guiding public policy decisions.

MenACWY-TT vaccine for active immunization against invasive meningococcal disease

Meningococcal disease remains a significant global cause of morbidity and mortality despite the availability of polysaccharide and conjugate vaccines. The implementation of monovalent meningococcal serogroup C vaccine in developed countries has significantly decreased the incidence of meningococcal disease, while the recent introduction of monovalent serogroup A conjugate vaccine in the African meningitis belt aims to reduce the incidence of high endemic disease in this area. Three quadrivalent meningococcal vaccines have already been licensed; a polysaccharide (MenACWY-PS) and two conjugated (MenACWY-DT and MenACWY-CRM) vaccines. An investigational MenACWY-TT vaccine is described in this article. Clinical trials in infants older than 9 months of age, toddlers, children, adolescents and adults have indicated that this vaccine is well tolerated and immunogenic. The inclusion of a spacer molecule coupled with the polysaccharide (for serogroups A and C) and tetanus toxoid as the carrier protein aims to elicit robust immune responses. The tolerability of this vaccine is comparable to that of polysaccharide quadrivalent vaccines and monovalent meningococcal serogroup C vaccines. More importantly, the immunogenicity, antibody persistence and induction of immune memory aim to provide protection to a wide range of susceptible subjects.

Genetic and antigenic characterization of invasive endemic serogroup B Neisseria meningitidis from Ontario, Canada, in 2001-2010

This study examined the antigenic and genetic diversity of serogroup B Neisseria meningitidis (MenB) recovered from invasive meningococcal disease (IMD) cases in Ontario, Canada, over the period 2001-2010 during which no MenB outbreaks had occurred. MenB was found to be responsible for 39 % of all IMD cases, with the remaining cases caused mainly by serogroups Y (28 %), C (23.5 %) and W135 (8 %). One hundred and ninety-three individual MenB case isolates were collected and characterized. Of the 88 sequence types (STs) identified, 75 were grouped into 14 known clonal complexes (CCs), whilst 13 STs were not assigned to any known CC. Fifty-seven different PorA genotypes and 88 STs defined the diversity of invasive MenB in Ontario, which supported the endemic nature of MenB disease in Ontario. Despite the presence of the hypervirulent ST-41/44 and ST-32 CCs, no single ST was predominant and responsible for a large number of IMD cases. Although the Québec outbreak clone of ST-269 was also found in Ontario, the 20 case isolates were genetically diverse: they grouped into seven STs and did not have a predominant PorA genotype. eburst analysis identified a new CC responsible for 14.5 % of the MenB case isolates. The six most common PorA variable region 2 (VR2) genotypes (VR2-9, -4, -14, -16, -13-1 and -16-3) were found in 67 % of invasive MenB isolates.

Clonal analysis of Neisseria meningitidis serogroup B strains in South Africa, 2002 to 2006: emergence of new clone ST-4240/6688

From August 1999 through July 2002, hyperinvasive Neisseria meningitidis serogroup B (MenB) clonal complexes (CCs), namely, ST-32/ET-5 (CC32) and ST-41/44/lineage 3 (CC41/44), were predominant in the Western Cape Province of South Africa. This study analyzed MenB invasive isolates from a national laboratory-based surveillance system that were collected from January 2002 through December 2006. Isolates were characterized by pulsed-field gel electrophoresis (PFGE) (n = 302), and multilocus sequence typing (MLST) and PorA and FetA typing were performed on randomly selected isolates (34/302, 11%). In total, 2,400 cases were reported, with the highest numbers from Gauteng Province (1,307/2,400, 54%) and Western Cape Province (393/2,400, 16%); 67% (1,617/2,400) had viable isolates and 19% (307/1,617) were identified as serogroup B. MenB incidence remained stable over time (P = 0.77) (average incidence, 0.13/100,000 population [range, 0.10 to 0.16/100,000 population]). PFGE (302/307, 98%) divided isolates (206/302, 68%) into 13 clusters and 96 outliers. The largest cluster, B1, accounted for 25% of isolates (76/302) over the study period; its prevalence decreased from 43% (20/47) in 2002 to 13% (8/62) in 2006 (P < 0.001), and it was common in the Western Cape (58/76, 76%). Clusters B2 and B3 accounted for 10% (31/302) and 6% (19/302), respectively, and showed no significant change over time and were predominant in Gauteng. Randomly selected isolates from clusters B1, B2, and B3 belonged to CC32, CC41/44, and the new CC4240/6688, respectively. Overall, 15 PorA and 12 FetA types were identified. MenB isolates were mostly diverse with no single dominant clone; however, CC32 and CC41/44 accounted for 35% and the new CC4240/6688 was the third most prevalent clone.

Epidemiology of serogroup B invasive meningococcal disease in Ontario, Canada, 2000 to 2010

BACKGROUND

Invasive meningococcal disease (IMD) caused by serogroup B is the last major serogroup in Canada to become vaccine-preventable. The anticipated availability of vaccines targeting this serogroup prompted an assessment of the epidemiology of serogroup B disease in Ontario, Canada.

METHODS

We retrieved information on confirmed IMD cases reported to Ontario's reportable disease database between January 1, 2000 and December 31, 2010 and probabilistically-linked these cases to Public Health Ontario Laboratory records. Rates were calculated with denominator data obtained from Statistics Canada. We calculated a crude number needed to vaccinate using the inverse of the infant (<1 year) age-specific incidence multiplied by expected vaccine efficacies between 70% and 80%, and assuming only direct protection (no herd effects).

RESULTS

A total of 259 serogroup B IMD cases were identified in Ontario over the 11-year period. Serogroup B was the most common cause of IMD. Incidence ranged from 0.11 to 0.27/100,000/year, and fluctuated over time. Cases ranged in age from 13 days to 101 years; 21.4% occurred in infants, of which 72.7% were <6 months. Infants had the highest incidence (3.70/100,000). Case-fatality ratio was 10.7% overall. If we assume that all infant cases would be preventable by vaccination, we would need to vaccinate between 33,784 and 38,610 infants to prevent one case of disease.

CONCLUSIONS

Although rare, the proportion of IMD caused by serogroup B has increased and currently causes most IMD in Ontario, with infants having the highest risk of disease. Although serogroup B meningococcal vaccines are highly anticipated, our findings suggest that decisions regarding publicly funding serogroup B meningococcal vaccines will be difficult and may not be based on disease burden alone.

Invasive serogroup B Neisseria meningitidis in Quebec, Canada, 2003 to 2010: persistence of the ST-269 clone since it first emerged in 2003

In the era after the introduction of the meningococcal serogroup C conjugate vaccine, from 1 January 2003 to 31 December 2010, serogroup B meningococci were the major cause of invasive meningococcal disease in the province of Québec, Canada, being responsible for 72% of all meningococcal disease cases. Of the 334 invasive serogroup B Neisseria meningitidis strains analyzed, 53.9% belonged to the ST-269 clonal complex (CC). Since it first emerged in 2003, the percentage of invasive serogroup B isolates that belonged to the ST-269 CC had increased from 35% in 2003 to 76% in 2010. Among the 180 meningococci in the ST-269 CC, 91.7% belonged to a single ST (ST-269). The most common PorA genotypes identified in the ST-269 CC were (i) VR1 19-1, VR2 15-11, VR3 36 (84%) and (ii) VR1 18-7, VR2 9, VR3 35-1 (9%). Cases of invasive disease due to the ST-269 CC were commonly found in those aged 11 to 19 years (30.5%) and 20 to 40 years (25.5%). Meningococci of the ST-269 CC were uncommon in other Canadian provinces. In contrast to the ST-269 CC, invasive serogroup B meningococci that belonged to the ST-41/44 CC were much more diverse genetically. However, one ST (ST-571), which is uncommon in the United States, accounted for 35% of all cases due to this CC. The current finding suggests that the ST-269 clone may indeed represent an emerging hypervirulent clone of meningococci.

Genetic and antigenic analysis of invasive serogroup C Neisseria meningitidis in Canada: A decrease in the electrophoretic type (ET)-15 clonal type and an increase in the proportion of isolates belonging to the ET-37 (but not ET-15) clonal type during the period from 2002 to 2009

BACKGROUND

Serogroup C meningococcal disease has been endemic in Canada since the early 1990s, with periods of hyperendemic disease documented in the past two decades. The present study characterized invasive serogroup C meningococci in Canada during the period from 2002 to 2009.

METHODS

Serogroup C meningococci were serotyped using monoclonal antibodies. Their clonal types were identified by either multilocus enzyme electrophoresis or multilocus sequence typing.

RESULTS

The number of invasive serogroup C Neisseria meningitidis isolates received at the National Microbiology Laboratory (Winnipeg, Manitoba) for characterization has dropped from a high of 173 isolates in 2001 to just 17 in 2009, possibly related to the introduction of the serogroup C meningococcal conjugate vaccine. Before 2006, 80% to 95% of all invasive serogroup C meningococci belonged to the electrophoreic type (ET)-15 clonal type, and the ET-37 (but not ET-15) type only accounted for up to 5% of all isolates. However, beginning in 2006, the percentage of the ET-15 clonal type decreased while the ET-37 (but not ET-15) type increased from 27% in 2006 to 52% in 2009. The percentage of invasive serogroup C isolates not belonging to either ET-15 or ET-37 also increased. Most ET-15 isolates expressed the antigenic formula of C:2a:P1.7,1 or C:2a:P1.5. In contrast, the ET-37 (but not ET-15) isolates mostly expressed the antigens of C:2a:P1.5,2 or C:2a:P1.2.

CONCLUSION

A shift in the antigenic and clonal type of invasive serogroup C meningococi was noted. This finding suggests vigilance in the surveillance of meningoccocal disease is warranted.

The changing and dynamic epidemiology of meningococcal disease

The epidemiology of invasive meningococcal disease continues to change rapidly, even in the three years since the first Meningococcal Exchange Meeting in 2008. Control of disease caused by serogroup C has been achieved in countries that have implemented meningococcal C or quadrivalent meningococcal ACWY conjugate vaccines. Initiation of mass immunization programs with meningococcal A conjugate vaccines across the meningitis belt of Africa may lead to the interruption of cyclical meningococcal epidemics. A meningococcal B vaccination program in New Zealand has led to a decreased incidence of high rates of endemic serogroup B disease. Increases in serogroup Y disease have been observed in certain Nordic countries which, if they persist, may require consideration of use of a multiple serogroup vaccine. The imminent availability of recombinant broadly protective serogroup B vaccines may provide the tools for further control of invasive meningococcal disease in areas where serogroup B disease predominates. Continued surveillance of meningococcal disease is essential; ongoing global efforts to improve the completeness of reporting are required.

Potential of recombinant opa proteins as vaccine candidates against hyperinvasive meningococci

Neisseria meningitidis causes half a million cases of septicemia and meningitis globally each year. The opacity (Opa) integral outer membrane proteins from N. meningitidis are polymorphic and highly immunogenic. Particular combinations of Opa proteins are associated with the hyperinvasive meningococcal lineages that have caused the majority of serogroup B and C meningococcal disease in industrialized countries over the last 60 years. For the first time, this genetic structuring of a diverse outer membrane protein family has been used to select a novel combination of representative antigens for immunogenicity testing. Fourteen recombinant Opa variants were produced and used in murine immunizations inducing an increase in specific antimeningococcal total IgG levels. All 14 Opa proteins elicited bactericidal antibodies against at least one hyperinvasive meningococcal isolate, and most isolates from each hyperinvasive lineage were killed by at least one Opa antiserum at a titer of 1:16 or greater. Cross-reactive bactericidal antibody responses were observed among clonal complexes. A theoretical coverage of 90% can be achieved by using a particular combination of 6 Opa proteins against an isolate collection of 227 recent United Kingdom disease cases. This study indicates the potential of Opa proteins to provide broad coverage against multiple meningococcal hyperinvasive lineages.

Detection of a geographical and endemic cluster of hyper-invasive meningococcal strains

From 2006 to December 2009, 45 out of the 513 strains isolated from patients with invasive meningococcal disease in Belgium, were identified as Neisseria meningitidis serogroup B, non-serotypeable, subtype P1.14 (B:NT:P1.14). Most cases were geographically clustered in the northern part of the country. Multilocus Sequence Typing and antigen gene sequencing combined with Pulsed-Field Gel electrophoresis were used to investigate this cluster. Molecular typing showed that 39 out of these 45 N. meningitidis strains belonged to the clonal complex cc-269. The presence of the same PorA Variable Regions (VR1-VR2: 22, 14), the FetA allele (F5-1) and the highly similar Pulsed-Field Gel Electrophoresis profiles, supported genetic relatedness for 38 out of these 39 isolates. Retrospective analysis of B:NT:P1.22,14 isolates from 1999 onwards suggested that these strains belonging to the cc-269 complex, first emerged in the Belgian province of West-Flanders in 2004. This study showed that the combination of molecular tools with classical methods enabled reliable outbreak detection as well as a cluster identification.

The elusive meningococcal meningitis serogroup: a systematic review of serogroup B epidemiology

Background

Invasive meningococcal disease (IMD), is a widely distributed, complex human disease affecting all age categories. The causative agent, Neisseria meningitidis, is spread through aerosol respiratory droplets. 13 different serogroups have been identified, each with varying epidemiological features including prevalence, virulence, immunogenicity, geographical and temporal distribution. Although preventative measures are available for several of the serogroups, meningococcal disease caused by serogroup B is of particular interest due to the challenge it presents concerning vaccine development.

Methods

A systematic review of peer reviewed studies and reports, the collection of data from national and international health resources, along with the analysis of the Multi Locus Sequence Typing database was carried out aimed at collecting information concerning serogroup B IMD and the epidemiology attached to it.

Results

A continuous output of related and novel STs occurring worldwide in terms of the hypervirulent clonal complexes was observed both in published studies and the MLST database in this case using the eburst software, which highlights the genetically diverse nature of serogroup B strains.

Conclusions

With the recent dominance of serogroup B IMD seen in many countries, along with the presence of antibiotic resistance, vaccine development needs to target areas of the bacterium which tackle this widespread and heterogeneous aspect of meningococcal meningitis disease.

Molecular epidemiology of meningococci: application of DNA sequence typing

Neisseria meningitidis is an invasive pathogen contributing significantly to childhood mortality worldwide. The organism is adapted to the human host and transmitted by close contact or droplet aerosols. In comparison to healthy carriage, invasive disease is a rare event. Nevertheless, due to a high case-fatality rate and the fact that meningococcal infection is a communicable disease, molecular typing of meningococci has been driven forward considerably in the past decades. Multilocus and antigen sequence typing data are assembled in large databases accessible via the internet. For epidemiological purposes, representative case ascertainment strategies are necessary if data are to be exploited for trend analysis, geographic visualization, detection of abnormalities such as outbreaks, and prediction of vaccine coverage. In Europe, a consensus for molecular typing has been achieved.

Sequence conservation of pilus subunits in Neisseria meningitidis

The rapid onset and dramatic consequences of Neisseria meningitidis infections make the design of a broadly protective vaccine a priority for public health. There is an ongoing quest for meningococcal components that are surface exposed, widely conserved and can induce protective antibodies. Type IV pili (Tfp) are filamentous structures with a key role in pathogenesis that extend beyond the surface of the bacteria and have demonstrated vaccine potential. However, extensive antigenic variation of PilE, the major subunit of Tfp, means that they are currently considered to be unsuitable vaccine components. Recently it has been shown that Tfp also contain low abundance pilins ComP, PilV and PilX in addition to PilE. This prompted us to examine the prevalence and sequence diversity of these proteins in a panel of N. meningitidis disease isolates. We found that all minor pilins are highly conserved and the major pilin genes are also highly conserved within the ST-8 and ST-11 clonal complexes. These data have important implications for the re-consideration of pilus subunits as vaccine antigens.

Global epidemiology of meningococcal disease

As reviewed in this paper, meningococcal disease epidemiology varies substantially by geographic area and time. The disease can occur as sporadic cases, outbreaks, and large epidemics. Surveillance is crucial for understanding meningococcal disease epidemiology, as well as the need for and impact of vaccination. Despite limited data from some regions of the world and constant change, current meningococcal disease epidemiology can be summarized by region. By far the highest incidence of meningococcal disease occurs in the meningitis belt of sub-Saharan Africa. During epidemics, the incidence can approach 1000 per 100,000, or 1% of the population. Serogroup A has been the most important serogroup in this region. However, serogroup C disease has also occurred, as has serogroup X disease and, most recently, serogroup W-135 disease. In the Americas, the reported incidence of disease, in the range of 0.3-4 cases per 100,000 population, is much lower than in the meningitis belt. In addition, in some countries such as the United States, the incidence is at an historical low. The bulk of the disease in the Americas is caused by serogroups C and B, although serogroup Y causes a substantial proportion of infections in some countries and W-135 is becoming increasingly problematic as well. The majority of meningococcal disease in European countries, which ranges in incidence from 0.2 to 14 cases per 100,000, is caused by serogroup B strains, particularly in countries that have introduced serogroup C meningococcal conjugate vaccines. Serogroup B also predominates in Australia and New Zealand, in Australia because of the control of serogroup C disease through vaccination and in New Zealand because of a serogroup B epidemic. Based on limited data, most disease in Asia is caused by serogroup A and C strains. Although this review summarizes the current status of meningococcal disease epidemiology, the dynamic nature of this disease requires ongoing surveillance both to provide data for vaccine formulation and vaccine policy and to monitor the impact of vaccines following introduction.

Immunochemical studies and genetic background of two Neisseria meningitidis isolates expressing unusual capsule polysaccharide antigens with specificities of both serogroup Y and W135

We described 2 unusual Neisseria meningitidis strains isolated from epidemiologically unrelated invasive meningococcal disease cases in Ontario, Canada. Both isolates have features typical of serogroup Y N. meningitidis: are of serotype 2c, are of the multi-locus sequence types typical of the serogroup Y strains in Canada, and are genotyped as serogroup Y based on a previously described PCR-ELISA method that detects the serogroup-Y-specific siaD gene. However, both strains were poly-agglutinable in both anti-Y and anti-W135 antisera. Further studies on 1 of these 2 isolates showed the presence of glucose and galactose as well as sialic acids in its purified capsular polysaccharide, suggesting the presence of both serogroup Y and serogroup W135 polysaccharides. Rabbit antisera produced to this strain contained antibodies to both purified serogroup Y and serogroup W135 capsular polysaccharides. Absorption experiments with either serogroup Y or serogroup W135 bacteria confirmed the presence of antibodies to these 2 different polysaccharides. DNA sequencing of the cps operon from both isolates revealed a siaD gene with 99.7% homology to the published siaD sequence from a serogroup Y strain but with 3 point mutations that all resulted in amino acid changes. How these strains may affect results of routine surveillance, PCR diagnosis, and immuno-protection by vaccination are discussed.

Which Pharmacovigilance for Vaccines?

Vaccines are not separate health products but anti-infectious medicines administered for the large part prophylactically and for which the effect is immunological and not pharmacological. They should be evaluated by the usual methods of clinical pharmacology and pharmacovigilance, taking into account certain specificities (mechanism of action, manufacture, frequent administration to healthy subjects, particular recommendations, etc.). Experience from some vaccination campaigns have revealed insufficiencies notably in data collection allowing evaluation of the interest of a vaccine to public health, its relevance to the recent epidemiology of the disease in question and long-term security. The absence of data can generate fear in the general population that is broadcast by anti-vaccination lobby. For a more optimal pharmacovigilance of vaccines, it is necessary to: (i) improve the coherence between the evaluating authorities; (ii) set up, in addition to the usual risk management plan, an active microbiological and epidemiological surveillance and to follow up exposed populations; (iii) have programmes of education of the medical community regarding vaccination and health education for the general public.

Clonal distribution of invasive Neisseria meningitidis serogroup C strains circulating from 1976 to 2005 in greater Sao Paulo, Brazil

Meningococcal disease is characterized by cyclic fluctuations in incidence, serogroup distribution, and antigenic profiles. In greater São Paulo, Brazil, there has been a constant increase in the incidence of serogroup C meningococcal disease since the late 1980s. To gain an understanding of changes in serogroup C meningococcal disease over three decades in greater São Paulo, Brazil, 1,059 invasive Neisseria meningitidis serogroup C isolates from 1976 and 2005 were analyzed. Three major clone complexes, sequence type (ST)-11, ST-8, and ST-103, were identified by multilocus sequence typing, and the isolates were characterized by serotyping and 16S rRNA typing. During the 30-year period, there were two major antigenic replacements: from 2a:P1.(5,2) to 2b:P1.3 and subsequently to 23:P1.14-6. All strains of clone ST-103 were characterized as serotype 23 and serosubtype P1.14-6. The origin of 23:P1.14-6 ST-103 complex strains is unknown, but efforts are needed to monitor its spread and define its virulence. The antigenic replacements we observed likely represent a mechanism to sustain meningococcal disease in the population as immunity to circulating strains accumulated.

Multilocus sequence typing for global surveillance of meningococcal disease

The global surveillance of bacterial pathogens is particularly important for bacteria with diverse and dynamic populations that cause periodic epidemics or pandemics. The isolate characterization methods employed for surveillance should: (1) generate unambiguous data; (2) be readily implemented in a variety of scenarios and be reproducible among laboratories; (3) be scalable and preferably available in a high throughput format; and (4) be cost effective. Multilocus sequence typing (MLST) was designed to meet these criteria and has been implemented effectively for a wide range of microorganisms. The 'Impact of meningococcal epidemiology and population biology on public health in Europe (EU-MenNet)' project had amongst its objectives: (1) to disseminate meningococcal MLST and sequence-based typing throughout Europe by establishing a centre for training and data generation, and (2) to produce a comprehensive Europe-wide picture of meningococcal disease epidemiology for the first time. Data produced from the project have shown the distribution of a relatively small number of STs, clonal complexes and PorA types that account for a large proportion of the disease-associated isolates in Europe. The project demonstrates how molecular typing can be combined with epidemiological data via the Internet for global disease surveillance.