Meningococcal disease before and after the introduction of meningococcal serogroup C conjugate vaccine. Federal District, Brazil

Objectives

To analyze the behavior of meningococcal disease in the Federal District, Brazil, from 2005 to 2011, and to assess the direct impact of the meningococcal serogroup C conjugate vaccine.

Methods

A descriptive study of cases of meningococcal disease among residents of the Federal District. We included in the study confirmed cases of meningococcal disease reported to the local surveillance. To reduce underreporting we compared data to the Brazilian Mortality Database and the Public Health Laboratory Database. We studied sociodemographic, clinical, and pathogen-related variables. For the assessment of the impact of meningococcal serogroup C conjugate vaccine, which was introduced in 2010 for children under two years of age, we compared the incidence of meningococcal disease before and after vaccine introduction in the recommended age groups for vaccination.

Results

We identified 309 cases of meningococcal disease, of which 52.1% were males. The average case fatality rate was 20.7%, the median age was three years and there was a predominance of serogroup C (70.2%) and C:23:P1.14-6 phenotype throughout the study period. In 2005–2009, 2010 and 2011, the incidence rates of meningococcal disease were 2.0, 1.8 and 0.8/100,000 inhabitants/year, while mortality rates were 0.4, 0.4 and 0.2/100,000 inhabitants/year, respectively. In the first and last periods, the incidence in poorer and more affluent areas were, respectively, 2.0 and 0.8, and 0.9 and 0.0/100,000 inhabitants/year. Comparing 2009 (the year prior to the introduction of meningococcal serogroup C conjugate vaccine) and 2011, there was 85% reduction in the incidence of serogroup C meningococcal disease in children under four years of age, from 9.0 to 1.3/100,000 (p < 0.01).

Conclusions

The meningococcal serogroup C conjugate vaccine strategy implemented in Brazil proved highly effective and had a strong direct impact on the target population. However, case fatality rates of meningococcal disease remain high with a wide gap in the risk of disease between poor and affluent areas, pointing to the need to reexamine the current strategy on a regular base.

Meningococcal groups C and Y and haemophilus B tetanus toxoid conjugate vaccine (HibMenCY-TT; MenHibrix(®)): a review

The meningococcal groups C and Y and Haemophilus b (Hib) tetanus toxoid conjugate vaccine (HibMenCY-TT) contains Neisseria meningitidis serogroup C and Y capsular polysaccharide antigens, and Hib capsular polysaccharide [polyribosyl-ribitol-phosphate (PRP)]. The HibMenCY-TT vaccine is available in the USA for use as active immunization to prevent invasive disease caused by N. meningitidis serogroups C (MenC) and Y (MenY), and Hib in children 6 weeks-18 months of age. HibMenCY-TT is the first meningococcal vaccine available for use in the USA that can be administered to infants as young as 6 weeks of age. In a randomized, controlled, phase III clinical trial, the HibMenCY-TT vaccine, administered to infants at 2, 4, 6 and 12-15 months of age, was immunogenic against MenC and MenY, and met the prespecified criteria for immunogenicity. Anti-PRP antibodies, which have been shown to correlate with protection against Hib invasive disease, were also induced in the infants who received the HibMenCY-TT vaccine, with induced levels of this antibody noninferior to those occurring in the control group of infants who received a Hib tetanus toxoid conjugate vaccine at 2, 4, and 6 months and a single dose of Hib conjugated to N. meningitidis outer membrane protein at 12-15 months. In several randomized, controlled clinical trials, HibMenCY-TT was coadministered with vaccines that are routinely administered to infants and toddlers in the USA. These vaccines included: diphtheria and tetanus toxoids and acellular pertussis adsorbed, hepatitis B (recombinant) and inactivated poliovirus vaccine combined; 7-valent Streptococcus pneumoniae polysaccharide conjugate vaccine; measles, mumps and rubella vaccine; and varicella vaccine. Coadministration of these vaccines did not interfere with the immunogenicity of the HibMenCY-TT vaccine. Similarly, immune responses to the coadministered vaccines were not affected by the HibMenCY-TT vaccine. The tolerability profile of the HibMenCY-TT vaccine in infants and toddlers in the phase III trial was considered to be clinically acceptable and comparable to that of the Hib conjugate vaccines received by the control group.

Recombinant Neisseria surface protein A is a potential vaccine candidate against Neisseria meningitides serogroup B

Neisseria meningitidis is the pathogen of epidemic encephalomyelitis and is responsible for permanent damage to the brain and nervous system. In the present study, the prokaryotic expression vector pGEX-6p-1/neisseria surface protein A (NspA) was constructed and the immune protective effect was investigated with the purified recombinant rNspA. Female BALB/c mice were immunized by intraperitoneal inoculation of rNspA, glutathione S-transferase (GST) or phosphate-buffered saline (PBS). The protection experiment in mice demonstrated that the protection rate of the rNspA group was 85% against the N. meningitidis strain MC58, and a serum bactericidal assay in vitro revealed that the serum bactericidal titer of the rNspA group reached 1:64 following three immunizations. The levels of specific immunoglobulin (Ig) A (SIgA), IgG, IgG1, IgG2a, IgG2b and IgG3 of mice in the rNspA group peaked at week six and were higher than those in the mice in the GST and PBS groups. The levels of stimulation index, interleukin-4 and interferon-γ in the culture supernatant of the spleen lymphocytes of the rNspA group increased in a time-dependent manner and were higher than those of the mice in the GST and PBS groups over the same period. The results suggested that rNspA may induce increased specific humoral and cellular immune responses, and that it is effectively protective against N. meningitidis serogroup B in mice. The present study offered novel evidence that may lead to the development of a novel effective N. meningitidis serogroup B vaccine.

Meningococcal serogroup B disease in Turkey: a guess or reality?

Each country chooses the appropriate vaccine against IMD depending on the locally prevalent serogroups of N. meningitides. Frequency of each meningococcal serogroup varies considerably over time and by geographical location. Despite the majority of IMD cases (85%) are caused by serogroups B and C in Europe, true prevalence of serogroup B IMD cases in Turkey is unclear. In one of the recent studies, the sharp decrease of serogroup B IMD from 35% down to 2.5% in a few years despite the absence of vaccination is confusing. Millions of European Turkish people travels from Europe to Turkey every year who could most probably carry serogroup B. It is obvious that a nationwide active surveillance is crucial to assess the the true epidemiology and burden of IMD which has a major impact on the choice of vaccine type and age interval the vaccination to be implemented.

Polysaccharide-specific B cell responses to vaccination in humans

The introduction of vaccines containing the capsular polysaccharides of N. meningitidis, S. pneumonia, and H. influenzae type b has driven a significant reduction in cases of disease caused by these bacteria. The polysaccharide-specific antibody responses following vaccination are well characterized, however less is known about the B cells underlying this response. Here, we summarize the plasma cell (PC) and memory B cell (BMEM) responses following plain polysaccharide and protein-polysaccharide conjugate vaccination, drawing together studies covering a range of vaccines and age groups. These studies show that infant primary PC and BMEM responses to polysaccharide-conjugate vaccines are low in relation to older age groups but are significantly higher following booster doses. PC kinetics have generally been found to follow a similar pattern irrespective of vaccine type or age group, whereas divergent BMEM responses have been reported following plain polysaccharide and conjugate vaccination. A degree of correlation between early BMEM responses and maintenance of protective antibody levels has been identified in some studies, but the relationship between the 2 remains unclear. Identification of the B cell subsets involved and the mechanisms by which they are induced may provide a better understanding of the role of B cells in maintaining protective immunity through vaccination.

Safety of a quadrivalent meningococcal serogroups A, C, W and Y conjugate vaccine (MenACWY-CRM) administered with routine infant vaccinations: results of an open-label, randomized, phase 3b controlled study in healthy infants

BACKGROUND

The highest risk for invasive meningococcal disease (IMD) is in infants aged <1 year. Quadrivalent meningococcal conjugate vaccination has the potential to prevent IMD caused by serogroups A, C, W and Y. This phase 3b, multinational, open-label, randomized, parallel-group, multicenter study evaluated the safety of a 4-dose series of MenACWY-CRM, a quadrivalent meningococcal conjugate vaccine, concomitantly administered with routine vaccinations to healthy infants.

METHODS

Two-month-old infants were randomized 3:1 to receive MenACWY-CRM with routine vaccines or routine vaccines alone at ages 2, 4, 6 and 12 months. Adverse events (AEs) that were medically attended and serious adverse events (SAEs) were collected from all subjects from enrollment through 18 months of age. In a subset, detailed safety data (local and systemic solicited reactions and all AEs) were collected for 7 days post vaccination. The primary objective was a non-inferiority comparison of the percentages of subjects with ≥1 severe systemic reaction during Days 1-7 after any vaccination of MenACWY-CRM plus routine vaccinations versus routine vaccinations alone (criterion: upper limit of 95% confidence interval [CI] of group difference <6%).

RESULTS

A total of 7744 subjects were randomized with 1898 in the detailed safety arm. The percentage of subjects with severe systemic reactions was 16% after MenACWY-CRM plus routine vaccines and 13% after routine vaccines alone (group difference 3.0% (95% CI -0.8, 6.4%). Although the non-inferiority criterion was not met, post hoc analysis controlling for significant center and group-by-center differences revealed that MenACWY-CRM plus routine vaccinations was non-inferior to routine vaccinations alone (group difference -0.1% [95% CI -4.9%, 4.7%]). Rates of solicited AEs, medically attended AEs, and SAEs were similar across groups.

CONCLUSION

In a large multinational safety study, a 4-dose series of MenACWY-CRM concomitantly administered with routine vaccines was clinically acceptable with a similar safety profile to routine vaccines given alone.

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.

A decade of invasive meningococcal disease surveillance in Poland

Background

Neisseria meningitidis is a leading etiologic agent of severe invasive disease. The objective of the study was to characterise invasive meningococcal disease (IMD) epidemiology in Poland during the last decade, based on laboratory confirmed cases.

Methods

The study encompassed all invasive meningococci collected between 2002 and 2011 in the National Reference Centre for Bacterial Meningitis. The isolates were re-identified and characterised by susceptibility testing, MLST analysis, porA and fetA sequencing. A PCR technique was used for meningococcal identification directly from clinical materials.

Results

In the period studied, 1936 cases of IMD were confirmed, including 75.6% identified by culture. Seven IMD outbreaks, affecting mostly adolescents, were reported; all were caused by serogroup C meningococci of ST-11. The highest incidence was observed among children under one year of age (15.71/100,000 in 2011). The general case fatality rate in the years 2010–2011 was 10.0%. Meningococci of serogroup B, C, Y and W-135 were responsible for 48.8%, 36.6%, 1.2% and 1.2% of cases, respectively. All isolates were susceptible to third generation cephalosporins, chloramphenicol, ciprofloxacin, and 84.2% were susceptible to penicillin. MLST analysis (2009–2011) revealed that among serogroup B isolates the most represented were clonal complexes (CC) ST-32CC, ST-18CC, ST-41/44CC, ST-213CC and ST-269CC, and among serogroup C: ST-103CC, ST-41/44CC and ST-11CC.

Conclusions

The detection of IMD in Poland has changed over time, but observed increase in the incidence of the disease was mostly attributed to changes in the surveillance system including an expanded case definition and inclusion of data from non-culture diagnostics.

Meningococcal polysaccharide A O-acetylation levels do not impact the immunogenicity of the quadrivalent meningococcal tetanus toxoid conjugate vaccine: results from a randomized, controlled phase III study of healthy adults aged 18 to 25 years

In this study, we compared the immunogenicities of two lots of meningococcal ACWY-tetanus toxoid conjugate vaccine (MenACWY-TT) that differed in serogroup A polysaccharide (PS) O-acetylation levels and evaluated their immunogenicities and safety in comparison to a licensed ACWY polysaccharide vaccine (Men-PS). In this phase III, partially blinded, controlled study, 1,170 healthy subjects aged 18 to 25 years were randomized (1:1:1) to receive one dose of MenACWY-TT lot A (ACWY-A) (68% O-acetylation), MenACWY-TT lot B (ACWY-B) (92% O-acetylation), or Men-PS (82% O-acetylation). Immunogenicity was evaluated in terms of serum bactericidal activity using rabbit complement (i.e., rabbit serum bactericidal activity [rSBA]). Solicited symptoms, unsolicited adverse events (AEs), and serious AEs (SAEs) were recorded. The immunogenicities, in terms of rSBA geometric mean titers, were comparable for both lots of MenACWY-TT. The vaccine response rates across the serogroups were 79.1 to 97.0% in the two ACWY groups and 73.7 to 94.1% in the Men-PS group. All subjects achieved rSBA titers of ≥1:8 for all serogroups. All subjects in the two ACWY groups and 99.5 to 100% in the Men-PS group achieved rSBA titers of ≥1:128. Pain was the most common solicited local symptom and was reported more frequently in the ACWY group (53.9 to 54.7%) than in the Men-PS group (36.8%). The most common solicited general symptoms were fatigue and headache, which were reported by 28.6 to 30.3% and 26.9 to 31.0% of subjects, respectively. Two subjects reported SAEs; one SAE was considered to be related to vaccination (blighted ovum; ACWY-B group). The level of serogroup A PS O-acetylation did not affect vaccine immunogenicity. MenACWY-TT (lot A) was not inferior to Men-PS in terms of vaccine response and was well tolerated.

A combined Haemophilus influenzae type B Neisseria meningitidis serogroup C tetanus toxoid conjugate vaccine is immunogenic and well-tolerated when coadministered with diphtheria, tetanus, acellular pertussis hepatitis B-inactivated poliovirus at 3, 5 and 11 months of age: results of an open, randomized, controlled study

BACKGROUND

This study evaluated the immunogenicity, reactogenicity and safety of the combined Haemophilus influenzae type B Neisseria meningitidis serogroup C tetanus toxoid conjugate vaccine (Hib-MenC-TT) coadministered with diphtheria, tetanus, acellular pertussis hepatitis B-inactivated poliovirus (DTPa-HBV-IPV) as 2 primary and 1 booster doses at 3, 5 and 11 months of age.

METHODS

In this phase III open study (NCT00327184), 709 infants were randomized in 2 parallel groups (1:1) to receive either Hib-MenC-TT coadministered with DTPa-HBV-IPV or control vaccines (MenC-TT coadministered with DTPa-HBV-IPV/Hib). Serum bactericidal activity for MenC (rSBA-MenC) and antibody concentrations against polyribosylribitol phosphate from Hib (anti-PRP) and hepatitis B (anti-HBs) were measured at 1 month after dose 2, before booster and 1 month after booster dose. Solicited (local/general) and unsolicited symptoms were assessed up to 4 and 31 days, respectively, after each vaccination. Serious adverse events were recorded throughout the study.

RESULTS

One month after dose 2, high percentages of infants in both groups had rSBA-MenC titers ≥ 8 (≥ 99.1%), anti-PRP concentrations ≥ 0.15 μg/mL (≥ 96.5%) and anti-HBs concentrations ≥ 10 mIU/mL (≥ 95.3%), which persisted up to the booster vaccination (≥ 94.5%, ≥ 86.1%, ≥ 94.2%) and increased again after the booster dose (100%, 100%, ≥ 99%). Exploratory analyses indicated that rSBA-MenC geometric mean titers were lower and anti-PRP geometric mean concentrations were higher in the infants vaccinated with Hib-MenC-TT compared with the control vaccines at all time points. The safety profiles of the coadministered vaccines were similar in both groups.

CONCLUSIONS

The Hib-MenC-TT and DTPa-HBV-IPV vaccines are immunogenic with a clinically acceptable safety profile when coadministered as 2 primary doses during infancy and 1 booster dose at 11 months of age.

Trends in the management of viral meningitis at United States children's hospitals

OBJECTIVE

To determine trends in the diagnosis and management of children with viral meningitis at US children's hospitals.

METHODS

We performed a multicenter cross sectional study of children presenting to the emergency department (ED) across the 41 pediatric tertiary-care hospitals participating in the Pediatric Health Information System between January 1, 2005, and December 31, 2011. A case of viral meningitis was defined by International Classification of Diseases, Ninth Revision, discharge diagnosis, and required performance of a lumbar puncture. We examined trends in diagnosis, antibiotic use, and resource utilization for children with viral meningitis over the study period.

RESULTS

We identified 7618 children with viral meningitis (0.05% of ED visits during the study period). Fifty-two percent of patients were <1 year of age, and 43% were female. The absolute number and the proportion of ED visits for children with viral meningitis declined from 0.98 cases per 1000 ED visits in 2005 to 0.25 cases in 2011 (P < .001). Most children with viral meningitis received a parenteral antibiotic (85%), and were hospitalized (91%). Overall costs for children for children with viral meningitis remain substantial (median cost per case $5056, interquartile range $3572-$7141).

CONCLUSIONS

Between 2005 and 2011, viral meningitis diagnoses at US children's hospitals declined. However, most of these children are hospitalized, and the cost for caring for these children remains considerable.

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.

Effect of vaccines on bacterial meningitis worldwide

Three bacteria--Haemophilus influenzae, Streptococcus pneumoniae, and Neisseria meningitidis--account for most acute bacterial meningitis. Measurement of the effect of protein-polysaccharide conjugate vaccines is most reliable for H influenzae meningitis because one serotype and one age group account for more than 90% of cases and the incidence has been best measured in high-income countries where these vaccines have been used longest. Pneumococcal and meningococcal meningitis are caused by diverse serotypes and have a wide age distribution; measurement of their incidence is complicated by epidemics and scarcity of surveillance, especially in low-income countries. Near elimination of H influenzae meningitis has been documented after vaccine introduction. Despite greater than 90% reductions in disease attributable to vaccine serotypes, all-age pneumococcal meningitis has decreased by around 25%, with little data from low-income settings. Near elimination of serogroup C meningococcal meningitis has been documented in several high-income countries, boding well for the effect of a new serogroup A meningococcal conjugate vaccine in the African meningitis belt.

A randomized study to assess the immunogenicity, antibody persistence and safety of a tetravalent meningococcal serogroups A, C, W-135 and Y tetanus toxoid conjugate vaccine in children aged 2-10 years

Incidence of meningococcal diseases is high in children, and effective vaccines are needed for this age group. In this phase II, open, controlled study, 309 children aged 2–10 y from Finland were randomized (3:1) into two parallel groups to receive one dose of meningococcal ACWY-tetanus toxoid conjugate vaccine (ACWY-TT group; n = 231) or a licensed meningococcal ACWY polysaccharide vaccine (Men-PS group; n = 78). Serum bactericidal activity using rabbit complement (rSBA) was evaluated up to three years post-vaccination. Exploratory comparisons suggested that rSBA vaccine response rates and geometric mean titers (GMTs) for each serogroup at one month post-vaccination and rSBA GMTs for serogroups A, W-135 and Y up to three years post-vaccination were higher in the ACWY-TT compared with Men-PS group, but did not detect any difference between groups in terms of rSBA-MenC GMTs at three years post-vaccination; this is explained by the higher proportion of children from the Men-PS group who were excluded because they were re-vaccinated with a monovalent meningococcal serogroup C vaccine due to loss of protective antibody levels against this serogroup. Although there was a higher incidence of local reactogenicity in the ACWY-TT group, general and unsolicited symptoms reporting rates were comparable in both groups. This study showed that MenACWY-TT was immunogenic with a clinically acceptable safety profile in children aged 2–10 y. MenACWY-TT induced higher functional antibody titers for all serogroups, which persisted longer for serogroups A, W-135 and Y, than the MenACWY polysaccharide vaccine. This study has been registered at www.clinicaltrials.gov NCT00427908.

The new multicomponent vaccine against meningococcal serogroup B, 4CMenB: immunological, functional and structural characterization of the antigens

Neisseria meningitidis is a major cause of endemic cases and epidemics of meningitis and devastating septicemia. Although effective vaccines exist for several serogroups of pathogenic N. meningitidis, conventional vaccinology approaches have failed to provide a universal solution for serogroup B (MenB) which consequently remains an important burden of disease worldwide. The advent of whole-genome sequencing changed the approach to vaccine development, enabling the identification of potential vaccine candidates starting directly with the genomic information, with a process named reverse vaccinology. The application of reverse vaccinology to MenB allowed the identification of new protein antigens able to induce bactericidal antibodies. Three highly immunogenic antigens (fHbp, NadA and NHBA) were combined with outer membrane vesicles and formulated for human use in a multicomponent vaccine, named 4CMenB. This is the first MenB vaccine based on recombinant proteins able to elicit a robust bactericidal immune response in adults, adolescents and infants against a broad range of serogroup B isolates. This review describes the successful story of the development of the 4CMenB vaccine, with particular emphasis on the functional, immunological and structural characterization of the protein antigens included in the vaccine.

Neisseria meningitidis serogroup B lipooligosaccharide genotyping reveals high prevalence of L2 strains in Spain and unexpected relationship with factor H-binding protein expression

Neisseria meningitidis may be classified according to the lipooligosaccharide immunotype. We show that this classification can be achieved by PCR genotyping of the genes involved in the lipooligosaccharide inner-core biosynthesis, lpt3, lpt6, lgtG and lot3. Genotyping data correlated well (90-100%) with mass spectrometry data and was, therefore, applied to screen a random subset of recent N. meningitidis serogroup B isolates from Europe. Analysis of the proportion of the different lipooligosaccharide types highlighted the predominance of L3 strains. Surprisingly, high rates of L2 type strains were found in Spain (17%, versus 2.5% in Germany and 1.9% in the United Kingdom). Therefore, we also investigated further these Spanish L2 strains in an attempt to explain such prevalence despite the known sensitivity of L2 immunotype to complement. We explored the hypothesis that these strains express high amounts of factor H-binding protein (fHbp), but we found, on the contrary, that L2 strains express low or undetectable amounts of fHbp. Our findings suggest that, in addition to a genetic analysis, a multivalent approach may be necessary to estimate the effectiveness of a N. meningitidis serogroup B vaccine.

Clinical validation of multiplex real-time PCR assays for detection of bacterial meningitis pathogens

Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae are important causes of meningitis and other infections, and rapid, sensitive, and specific laboratory assays are critical for effective public health interventions. Singleplex real-time PCR assays have been developed to detect N. meningitidis ctrA, H. influenzae hpd, and S. pneumoniae lytA and serogroup-specific genes in the cap locus for N. meningitidis serogroups A, B, C, W135, X, and Y. However, the assay sensitivity for serogroups B, W135, and Y is low. We aimed to improve assay sensitivity and develop multiplex assays to reduce time and cost. New singleplex real-time PCR assays for serogroup B synD, W135 synG, and Y synF showed 100% specificity for detecting N. meningitidis species, with high sensitivity (serogroup B synD, 99% [75/76]; W135 synG, 97% [38/39]; and Y synF, 100% [66/66]). The lower limits of detection (LLD) were 9, 43, and 10 copies/reaction for serogroup B synD, W135 synG, and Y synF assays, respectively, a significant improvement compared to results for the previous singleplex assays. We developed three multiplex real-time PCR assays for detection of (i) N. meningitidis ctrA, H. influenzae hpd, and S. pneumoniae lytA (NHS assay); (ii) N. meningitidis serogroups A, W135, and X (AWX assay); and (iii) N. meningitidis serogroups B, C, and Y (BCY assay). Each multiplex assay was 100% specific for detecting its target organisms or serogroups, and the LLD was similar to that for the singleplex assay. Pairwise comparison of real-time PCR between multiplex and singleplex assays showed that cycle threshold values of the multiplex assay were similar to those for the singleplex assay. There were no substantial differences in sensitivity and specificity between these multiplex and singleplex real-time PCR assays.

Cost-effectiveness analysis of a universal infant immunization program with meningococcal C conjugate vaccine in Brazil

OBJECTIVE

To analyze the cost-effectiveness of a meningococcal C vaccination program in Brazil.

METHODS

A hypothetical cohort of 3,194,038 children born in Brazil in 2006 was followed for 10 years. A decision tree model was developed using the TreeAge Pro 2007 software program to compare universal infant vaccination with the current program. Epidemiological and cost estimates were based on data retrieved from National Health Information Systems and the literature. The analysis was conducted from the public health care system and societal perspectives. Costs are expressed in 2006 Brazilian reals (R$).

RESULTS

At 94% coverage, the program would avoid 1,218 cases, 210 deaths, and 14,473 life-years lost, a reduction of, respectively, 45%, 44%, and 44%, for the 10-year period. Vaccination costs of R$320.9 million would not be offset by R$4 to R$7.9 million decreases in disease treatment costs. A national vaccination program would cost R$21,620 per life-year saved from the perspective of the health-care system and R$21,896 per life-year saved from society's perspective. Results were most sensitive to case fatality rate, disease incidence, and vaccine cost.

CONCLUSIONS

A universal childhood vaccination program against meningococcal C proved to be a cost-effective strategy, supporting the recent decision of the Brazilian government. These results could contribute to defining the most favorable price of the vaccine and to monitoring its impact on the population.

Aseptic meningitis caused by Leptospira spp diagnosed by polymerase chain reaction

Leptospirosis is a zoonotic disease caused by the pathogenic Leptospira spp. The clinical presentations are diverse, ranging from undifferentiated fever to fulminant disease including meningeal forms. The neurological leptospirosis forms are usually neglected. The aim of this study was to investigate leptospirosis as the cause of aseptic meningitis using different diagnostic techniques including the polymerase chain reaction (PCR). Thirty-nine cerebrospinal fluid (CSF) samples from patients presenting with meningeal abnormalities, predominance of lymphocytes and negative results by traditional microbiological tests were processed by leptospiral culture, anti-leptospiral antibody response and PCR. Leptospira spp DNA was detected in 23 (58.97%) of the CSF samples. Anti-leptospiral antibodies were found in 13 (33.33%) CSF samples. Twelve CSF samples were positive by PCR assay and negative by microscopic agglutination test (MAT) assay. Two CSF samples were positive by MAT and negative by PCR. The positive and negative agreement between both tests was 11 and 14, respectively. CSF samples from six cases of unknown diagnosis were positive by PCR assay. Eight cases showed positive results using PCR and MAT. Leptospirosis could be detected by PCR assay from the 3rd-26th day after illness onset. The sensitivity of the PCR was assessed with confirmed cases of leptospirosis (by MAT) and found to be 89.5%. All CSFs were negative by culture. PCR was found to be a powerful tool for diagnosing meningitis cases of leptospirosis. We recommend that it may be used as a supplementary diagnostic tool, especially in the early stages of the disease, when other diagnostic techniques such as serology are not sensitive.

Meningococcal factor H binding proteins in epidemic strains from Africa: implications for vaccine development

BACKGROUND

Factor H binding protein (fHbp) is an important antigen for vaccines against meningococcal serogroup B disease. The protein binds human factor H (fH), which enables the bacteria to resist serum bactericidal activity. Little is known about the vaccine-potential of fHbp for control of meningococcal epidemics in Africa, which typically are caused by non-group B strains.

METHODOLOGY/PRINCIPAL FINDINGS

We investigated genes encoding fHbp in 106 serogroup A, W-135 and X case isolates from 17 African countries. We determined complement-mediated bactericidal activity of antisera from mice immunized with recombinant fHbp vaccines, or a prototype native outer membrane vesicle (NOMV) vaccine from a serogroup B mutant strain with over-expressed fHbp. Eighty-six of the isolates (81%) had one of four prevalent fHbp sequence variants, ID 4/5 (serogroup A isolates), 9 (W-135), or 74 (X) in variant group 1, or ID 22/23 (W-135) in variant group 2. More than one-third of serogroup A isolates and two-thirds of W-135 isolates tested had low fHbp expression while all X isolates tested had intermediate or high expression. Antisera to the recombinant fHbp vaccines were generally bactericidal only against isolates with fHbp sequence variants that closely matched the respective vaccine ID. Low fHbp expression also contributed to resistance to anti-fHbp bactericidal activity. In contrast to the recombinant vaccines, the NOMV fHbp ID 1 vaccine elicited broad anti-fHbp bactericidal activity, and the antibodies had greater ability to inhibit binding of fH to fHbp than antibodies elicited by the control recombinant fHbp ID 1 vaccine.

CONCLUSION/SIGNIFICANCE

NOMV vaccines from mutants with increased fHbp expression elicit an antibody repertoire with greater bactericidal activity than recombinant fHbp vaccines. NOMV vaccines are promising for prevention of meningococcal disease in Africa and could be used to supplement coverage conferred by a serogroup A polysaccharide-protein conjugate vaccine recently introduced in some sub-Saharan countries.

Conjugate Meningococcal Vaccines Development: GSK Biologicals Experience

Meningococcal diseases are serious threats to global health, and new vaccines specifically tailored to meet the age-related needs of various geographical areas are required. This paper focuses on the meningococcal conjugate vaccines developed by GSK Biologicals. Two combined conjugate vaccines were developed to help protect infants and young children in countries where the incidence of meningococcal serogroup C or serogroup C and Y disease is important: Hib-MenC-TT vaccine, which offers protection against Haemophilus influenzae type b and Neisseria meningitidis serogroup C diseases, is approved in several countries; and Hib-MenCY-TT vaccine, which adds N. meningitidis serogroup Y antigen, is currently in the final stages of development. Additionally, a tetravalent conjugate vaccine (MenACWY-TT) designed to help protect against four meningococcal serogroups is presently being evaluated for global use in all age groups. All of these vaccines were shown to be highly immunogenic and to have clinically acceptable safety profiles.

Meningococcal meningitis

OPINION STATEMENT

Meningococcal meningitis (MM) is the most common presentation of meningococcal disease and an important cause of morbidity and mortality worldwide. When MM is associated with shock, early recognition and treatment of shock is essential. No investigation should delay starting antibiotics once the diagnosis is suspected. Corticosteroids can be started at the same time as the antibiotics or just before, but this is not a specific recommendation for MM. Low-dose steroids should be used in meningococcal disease with refractory shock. Altered blood flow, cerebral edema, and raised intracranial pressure are problems that should be considered in all patients with MM and decreased consciousness level. When mechanical ventilation is required, the target carbon dioxide level is 4.0 to 4.5 kPa, with avoidance of hypocapnia. Seizures, although not frequent, can occur in MM and require prompt treatment. Other treatments, such as mannitol and activated protein C, should be avoided. Potential new treatments requiring further investigation include neuroprotection with hypothermia or glycerol.

The management of the orthopaedic sequelae of meningococcal septicaemia: patients treated to skeletal maturity

Septicaemia resulting from meningococcal infection is a devastating illness affecting children. Those who survive can develop late orthopaedic sequelae from growth plate arrests, with resultant complex deformities. Our aim in this study was to review the case histories of a series of patients with late orthopaedic sequelae, all treated by the senior author (CFB). We also describe a treatment strategy to address the multiple deformities that may occur in these patients. Between 1997 and 2009, ten patients (seven girls and three boys) were treated for late orthopaedic sequelae following meningococcal septicaemia. All had involvement of the lower limbs, and one also had involvement of the upper limbs. Each patient had a median of three operations (one to nine). Methods of treatment included a combination of angular deformity correction, limb lengthening and epiphysiodesis. All patients were skeletally mature at the final follow-up. One patient with bilateral below-knee amputations had satisfactory correction of her right amputation stump deformity, and has complete ablation of both her proximal tibial growth plates. In eight patients length discrepancy in the lower limb was corrected to within 1 cm, with normalisation of the mechanical axis of the lower limb. Meningococcal septicaemia can lead to late orthopaedic sequelae due to growth plate arrests. Central growth plate arrests lead to limb-length discrepancy and the need for lengthening procedures, and peripheral growth plate arrests lead to angular deformities requiring corrective osteotomies and ablation of the damaged physis. In addition, limb amputations may be necessary and there may be altered growth of the stump requiring further surgery. Long-term follow-up of these patients is essential to recognise and treat any recurrence of deformity.

Immunogenicity of a single dose of tetravalent meningococcal serogroups A, C, W-135, and Y conjugate vaccine administered to 2- to 10-year-olds is noninferior to a licensed-ACWY polysaccharide vaccine with an acceptable safety profile

BACKGROUND

Meningococcal disease remains an important cause of invasive bacterial infections in children less than 5 years of age. Immunogenicity and safety of the investigational ACWY vaccine conjugated with tetanus toxoid (ACWY-TT, GlaxoSmithKline Biologicals) were evaluated in 1501 healthy 2- to 10-year-old children in the Philippines, India, Lebanon, and Saudi Arabia.

METHODS

Children were randomized (3:1) to receive ACWY-TT or licensed tetravalent meningococcal polysaccharide vaccine (Mencevax, GlaxoSmithKline, Men-PS). Diary cards were used to collect solicited symptoms for 4 days after vaccination. Serious adverse events were reported for 6 months. Serum bactericidal activity (rSBA, rabbit complement) was measured before and 1 month after vaccination in the first 75% of subjects enrolled in each country.

RESULTS

The statistical criteria for noninferiority in terms of rSBA vaccine responses were reached. Exploratory analyses showed that postvaccination rSBA titers ≥ 1:8 and ≥ 1:128 were significantly higher after ACWY-TT than Men-PS for serogroups C, W-135, and Y, and rSBA vaccine responses and geometric mean antibody titers were significantly higher for all 4 serogroups after administration of ACWY-TT. Noninferiority in terms of incidences of grade 3 general symptoms was not demonstrated. ACWY-TT was well tolerated with grade 3 events reported in <1% of subjects per group. No serious adverse events were considered related to vaccination.

CONCLUSION

ACWY-TT was immunogenic in children between 2 to 10 years of age with a clinically acceptable safety profile that resembled licensed Men-PS. These data support a positive benefit/risk ratio for the ACWY-TT vaccine.

Immunogenicity and safety of an investigational combined haemophilus influenzae type B-Neisseria meningitidis serogroups C and Y-tetanus toxoid conjugate vaccine

BACKGROUND

Neisseria meningitidis serogroups B, C, and Y cause most meningococcal disease in industrialized countries. A Haemophilus influenzae type b-meningococcal serogroups C and Y-tetanus toxoid conjugate vaccine (HibMenCY-TT) was evaluated.

METHODS

A total of 1104 infants (randomized 3:1:1) were vaccinated at 2, 4, and 6 months with HibMenCY-TT, MenC-CRM197 + Hib-TT, or Hib-TT. At 12 to 15 months, HibMenCY-TT and MenC-CRM-primed children received HibMenCY-TT; Hib-TT-primed received N. meningitidis serogroup B Hib-outer membrane protein complex. Antibody concentrations and rabbit/human complement serum bactericidal antibody titers (rSBA/hSBA) were determined. Safety was monitored after each dose (diary cards for first 31 days) until 6 months postdose 4.

RESULTS

Postdose 3, rates of antipolyribosylribitol phosphate ≥ 1 μg/mL and rSBA-MenC ≥1:128 in HibMenCY-TT recipients were noninferior to licensed controls. Percentages reaching 0.15 μg/mL (1.0 μg/mL postdose 3) and antipolyribosylribitol phosphate GMC were significantly higher after HibMenCY-TT than Hib-TT postdose 2 and postdose 3. The GMC remained significantly higher before and after dose 4. Proportions of HibMenCY-TT recipients with rSBA ≥ 1:8 were 95.6% (MenC), 98.6% (MenY) postdose-2, ≥ 99% for MenC/Y postdose 3 and 4; hSBA ≥ 1:4 were 95.5% (MenC), 89.8% (MenY) postdose 2, >97% for MenC/Y postdose 3 and 4. HibMenCY-TT had a similar safety profile to control vaccines.

CONCLUSIONS

HibMenCY-TT induced noninferior Hib and MenC responses compared with monovalent Hib and MenC conjugates with a comparable safety profile. Bactericidal antibodies against MenC/Y were induced after 2 doses of HibMenCY-TT.

Challenges in immunisation against bacterial infection in children

Polysaccharide-encapsulated organisms such as S. pneumoniae, H. influenzae type b and N. meningitidis are the leading causes of serious invasive bacterial diseases and pneumonia in children. The use of conjugate vaccines in developed countries has markedly decreased the burden of disease and mortality from these organisms through direct protection of the immunised and through herd immunity. Although conjugate vaccines are highly immunogenic, antibody levels after immunisation in early infancy wane, leading to the need for programmes which include booster doses. Understanding the generation of long-term immunity could lead to improvements in vaccine formulation and scheduling with the ultimate goal of providing more sustained protection. Prematurity is a risk factor for disease caused by polysaccharide-encapsulated bacteria and the available data indicate that preterm infants should be immunised according to their chronological age to provide early protection.