Bacterial meningitis epidemiology and return of Neisseria meningitidis serogroup A cases in Burkina Faso in the five years following MenAfriVac mass vaccination campaign

Incidence rates of malaria, meningitis, and mortality in children younger than 5 years: a prospective cohort study in Ghana and Kenya before the roll-out of the RTS,S/AS01E malaria vaccine from 2016 to 2022

BACKGROUND

The RTS,S/AS01E malaria vaccine was introduced in selected communities of Ghana, Kenya, and Malawi in 2019 under a WHO-coordinated pilot programme. The scarcity of background disease incidence rates might hamper the assessment of vaccine safety and effectiveness. We aimed to determine the incidence rates of malaria, meningitis, and death, and health outcomes leading to hospital admission in children younger than 5 years enrolled before RTS,S/AS01E implementation. Interim results from EPI-MAL-002 up to Oct 5, 2018, were reported previously. Here, we report results from the final analysis of the pre-vaccine introduction study.

METHODS

This disease surveillance study combined two approaches: (1) prospective cohort event monitoring (home visits scheduled to mimic a future four-dose RTS,S/AS01E vaccination schedule [ie, a simulated vaccination schedule], with additional visits after the simulated schedule and continuous disease monitoring of outpatient visits and hospital admission) in children enrolled in two age groups (6-12 weeks [6-12W] and 5-17 months [5-17M]), and (2) hospital-based disease surveillance for children not enrolled in the prospective cohort, in three sites in Ghana and Kenya. Key outcomes were rates of meningitis, malaria, adverse events of special interest, other adverse events leading to hospital admission, all-cause mortality, and malaria-attributable mortality.

FINDINGS

The final analysis included 23 427 children: 9032 in the 6-12W age group, 9694 in the 5-17M age group, and 4701 in hospital-based disease surveillance. In the 5-17M age group (corresponding to the WHO-recommended age for RTS,S/AS01E vaccination), the incidence rates of meningitis and cerebral malaria within an at-risk period of 1 year after the simulated vaccination schedule were both equal to 28 (95% CI 9-65) per 100 000 person-years. There were 11 (0·1%) children with an adverse event of special interest during hospital admission. In the 5-17M age group, the all-cause mortality rate was 643 (95% CI 531-771) per 100 000 person-years.

INTERPRETATION

Observed incidence of meningitis and cerebral malaria were in the previously published range, whereas childhood mortality was lower, suggesting that the recent efforts to reduce mortality in children younger than 5 years have been impactful. Data from this study have public health use and will form the baseline evidence for ongoing evaluation of the benefit-risk of RTS,S/AS01E.

FUNDING

GSK and PATH.

Meningococcal Vaccination in the United States: Past, Present, And Future

Meningococcal disease is rare but serious, often striking previously healthy adolescents or young adults, with substantial morbidity and mortality. The incidence of meningococcal disease in the USA declined even prior to the issuance of routine recommendations for vaccination, although an uptick in incidence has occurred since 2022. Routine recommendations for adolescent MenACWY vaccination were issued in 2005, and recommendations for adolescent MenB vaccination based on shared clinical decision-making (SCDM) were issued in 2015. Although meningococcal vaccines are safe and effective, their limited duration of protection coupled with low disease incidence result in a high cost per case averted by vaccination, most notably with MenB vaccines. The low cost-effectiveness raises ethical concerns about resource use and the role of economic analyses in policy decisions. However, the potential for substantial public health impact remains. Outer membrane vesicle (OMV)-containing MenB vaccines provide some protection against gonorrhea infections. The recent development of pentavalent ABCWY vaccines provide the opportunity to reduce the number of injections and simplify implementation, provided MenACWY and MenB vaccine schedules are harmonized. Vaccine attributes, implementation issues, and resource utilization will be important considerations in optimization of the US adolescent meningococcal vaccination strategy.

Impact of Meningococcal ACWY Vaccination Program during 2017-18 Epidemic, Western Australia, Australia

The rising incidence of invasive meningococcal disease (IMD) caused by Neisseria meningitidis serogroup W in Western Australia, Australia, presents challenges for prevention. We assessed the effects of a quadrivalent meningococcal vaccination program using 2012-2020 IMD notification data. Notification rates peaked at 1.8/100,000 population in 2017; rates among Aboriginal and Torres Strait Islander populations were 7 times higher than for other populations. Serogroup W disease exhibited atypical manifestations and increased severity. Of 216 cases, 20 IMD-related deaths occurred; most (19/20) were in unvaccinated persons. After the 2017-2018 targeted vaccination program, notification rates decreased from 1.6/100,000 population in 2018 to 0.9/100,000 population in 2019 and continued to decline in 2020. Vaccine effectiveness (in the 1-4 years age group) using the screening method was 93.6% (95% CI 50.1%-99.2%) in 2018 and 92.5% (95% CI 28.2%-99.2%) in 2019. Strategic planning and prompt implementation of targeted vaccination programs effectively reduce IMD.

Meningococcal A conjugate vaccine coverage in the meningitis belt of Africa from 2010 to 2021: a modelling study

BACKGROUND

As of the end of 2021, twenty-four countries in the African meningitis belt have rolled out mass campaigns of MenAfriVac®, a meningococcal A conjugate vaccine (MACV) first introduced in 2010. Twelve have completed introduction of MACV into routine immunisation (RI) schedules. Although select post-campaign coverage data are published, no study currently comprehensively estimates MACV coverage from both routine and campaign sources in the meningitis belt across age, country, and time.

METHODS

In this modelling study, we assembled campaign data from the twenty-four countries that had introduced any immunisation activity during or before the year 2021 (Benin, Burkina Faso, Burundi, Cameroon, Central African Republic, Chad, Côte d'Ivoire, Democratic Republic of the Congo, Ethiopia, Eritrea, the Gambia, Ghana, Guinea, Guinea Bissau, Kenya, Mali, Mauritania, Niger, Nigeria, Senegal, South Sudan, Sudan, Togo and Uganda) via WHO reports and RI data via systematic review. Next, we modelled RI coverage using Spatiotemporal Gaussian Process Regression. Then, we synthesized these estimates with campaign data into a cohort model, tracking coverage for each age cohort from age 1 to 29 years over time for each country.

FINDINGS

Coverage in high-risk locations amongst children aged 1-4 in 2021 was estimated to be highest in Togo with 96.0% (95% uncertainty interval [UI] 92.0-99.0), followed by Niger with 87.2% (95% UI 85.3-89.0) and Burkina Faso, with 86.4% (95% UI 85.1-87.6). These countries had high coverage values driven by an initial successful mass immunisation campaign, followed by a catch-up campaign, followed by introduction of RI. Due to the influence of older mass vaccination campaigns, coverage proportions skewed higher in the 1-29 age group than the 1-4 group, with a median coverage of 82.9% in 2021 in the broader age group compared to 45.6% in the narrower age group.

INTERPRETATION

These estimates highlight where gaps in immunisation remain and emphasise the need for broader efforts to strengthen RI systems. This methodological framework can be applied to estimate coverage for any vaccine that has been delivered in both routine and supplemental immunisation activities.

FUNDING

Bill and Melinda Gates Foundation.

Efficacy and Effectiveness of the Meningococcal Conjugate Group A Vaccine MenAfriVac® in Preventing Recurrent Meningitis Epidemics in Sub-Saharan Africa

For more than a century, epidemic meningococcal disease mainly caused by serogroup A Neisseria meningitidis has been an important public health problem in sub-Saharan Africa. To address this problem, an affordable meningococcal serogroup A conjugate vaccine, MenAfriVac®, was developed specifically for populations in the African meningitis belt countries. MenAfriVac® was licensed based on safety and immunogenicity data for a population aged 1-29 years. In particular, the surrogate markers of clinical efficacy were considered to be the higher immunogenicity and the ability to prime immunological memory in infants and young children compared to a polysaccharide vaccine. Because of the magnitude of serogroup A meningitis epidemics and the high morbidity and mortality burden, the World Health Organization (WHO) recommended the MenAfriVac® deployment strategy, starting with mass vaccination campaigns for 1-29-year-olds to rapidly interrupt serogroup A person-to-person transmission and establish herd protection, followed by routine immunization of infants and toddlers to sustain protection and prevent epidemics. After licensure and WHO prequalification of MenAfriVac®, campaigns began in December 2010 in Burkina Faso, Mali, and Niger. By the middle of 2011, it was clear that the vaccine was highly effective in preventing serogroup A carriage and disease. Post introduction meningitis surveillance revealed that serogroup A meningococcal disease had disappeared from all age groups, suggesting that robust herd immunity had been achieved.

Modeling Optimal Laboratory Testing Strategies for Bacterial Meningitis Surveillance in Africa

Since 2010, the introduction of an effective serogroup A meningococcal conjugate vaccine has led to the near-elimination of invasive Neisseria meningitidis serogroup A disease in Africa’s meningitis belt. However, a significant burden of disease and epidemics due to other bacterial meningitis pathogens remain in the region. High-quality surveillance data with laboratory confirmation is important to monitor circulating bacterial meningitis pathogens and design appropriate interventions, but complete testing of all reported cases is often infeasible. Here, we use case-based surveillance data from 5 countries in the meningitis belt to determine how accurately estimates of the distribution of causative pathogens would represent the true distribution under different laboratory testing strategies. Detailed case-based surveillance data was collected by the MenAfriNet surveillance consortium in up to 3 seasons from participating districts in 5 countries. For each unique country-season pair, we simulated the accuracy of laboratory surveillance by repeatedly drawing subsets of tested cases and calculating the margin of error of the estimated proportion of cases caused by each pathogen (the greatest pathogen-specific absolute error in proportions between the subset and the full set of cases). Across the 12 country-season pairs analyzed, the 95% credible intervals around estimates of the proportion of cases caused by each pathogen had median widths of ±0.13, ±0.07, and ±0.05, respectively, when random samples of 25%, 50%, and 75% of cases were selected for testing. The level of geographic stratification in the sampling process did not meaningfully affect accuracy estimates. These findings can inform testing thresholds for laboratory surveillance programs in the meningitis belt.

Effectiveness of Meningococcal Vaccines at Reducing Invasive Meningococcal Disease and Pharyngeal Neisseria meningitidis Carriage: A Systematic Review and Meta-analysis

BACKGROUND

Invasive meningococcal disease (IMD), caused by Neisseria meningitidis, leads to significant morbidity and mortality worldwide. This review aimed to establish the effectiveness of meningococcal vaccines at preventing IMD and N. meningitidis pharyngeal carriage.

METHODS

A search within PubMed, Embase, Scopus, and unpublished studies up to 1 February 2020 was conducted.

RESULTS

After removal of duplicates, 8565 studies were screened and 27 studies included. Protection was provided by meningococcal C vaccines for group C IMD (odds ratio [OR], 0.13 [95% confidence interval {CI}, .07-.23]), outer membrane vesicle (OMV) vaccines against group B IMD (OR, 0.35 [95% CI, .25-.48]), and meningococcal A, C, W, Y (MenACWY) vaccines against group ACWY IMD (OR, 0.31 [95% CI, .20-.49]). A single time series analysis found a reduction following an infant 4CMenB program (incidence rate ratio, 0.25 [95% CI, .19-.36]). Multivalent MenACWY vaccines did not reduce carriage (relative risk [RR], 0.88 [95% CI, .66-1.18]), unlike monovalent C vaccines (RR, 0.50 [95% CI, .26-.97]). 4CMenB vaccine had no effect on group B carriage (RR, 1.12 [95% CI, .90-1.40]). There was also no reduction in group B carriage following MenB-FHbp vaccination (RR, 0.98 [95% CI, .53-1.79]).

CONCLUSIONS

Meningococcal conjugate C, ACWY, and OMV vaccines are effective at reducing IMD. A small number of studies demonstrate that monovalent C conjugate vaccines reduce pharyngeal N. meningitidis carriage. There is no evidence of carriage reduction for multivalent MenACWY, OMV, or recombinant MenB vaccines, which has implications for immunization strategies.

CLINICAL TRIALS REGISTRATION

CRD42018082085 (PROSPERO).

The effect of recombination on the evolution of a population of Neisseria meningitidis

Neisseria meningitidis (the meningococcus) is a major human pathogen with a history of high invasive disease burden, particularly in sub-Saharan Africa. Our current understanding of the evolution of meningococcal genomes is limited by the rarity of large-scale genomic population studies and lack of in-depth investigation of the genomic events associated with routine pathogen transmission. Here, we fill this knowledge gap by a detailed analysis of 2839 meningococcal genomes obtained through a carriage study of over 50,000 samples collected systematically in Burkina Faso, West Africa, before, during, and after the serogroup A vaccine rollout, 2009-2012. Our findings indicate that the meningococcal genome is highly dynamic, with highly recombinant loci and frequent gene sharing across deeply separated lineages in a structured population. Furthermore, our findings illustrate how population structure can correlate with genome flexibility, as some lineages in Burkina Faso are orders of magnitude more recombinant than others. We also examine the effect of selection on the population, in particular how it is correlated with recombination. We find that recombination principally acts to prevent the accumulation of deleterious mutations, although we do also find an example of recombination acting to speed the adaptation of a gene. In general, we show the importance of recombination in the evolution of a geographically expansive population with deep population structure in a short timescale. This has important consequences for our ability to both foresee the outcomes of vaccination programs and, using surveillance data, predict when lineages of the meningococcus are likely to become a public health concern.

Baseline incidence of meningitis, malaria, mortality and other health outcomes in infants and young sub-Saharan African children prior to the introduction of the RTS,S/AS01E malaria vaccine

Background

The lack of background disease incidence rates in sub-Saharan countries where the RTS,S/AS01_E malaria vaccine is being implemented may hamper the assessment of vaccine safety and effectiveness. This study aimed to document baseline incidence rates of meningitis, malaria, mortality, and other health outcomes prior to vaccine introduction through the Malaria Vaccine Implementation Programme.

Methods

An ongoing disease surveillance study is combining prospective cohort event monitoring and hospital-based disease surveillance in three study sites in Ghana and Kenya. An interim analysis was performed on the prospective cohort in which children were enrolled in two age-groups (the 5 to 17 months or 6 to 12 weeks age-group), capturing data in the framework of routine medical practice before the introduction of the malaria vaccine. Incidence and mortality rates were computed with 95% confidential intervals (CI) using an exact method for a Poisson variable.

Results

This analysis includes 14,329 children; 7248 (50.6%) in the 6 to 12 weeks age-group and 7081 (49.4%) in the 5 to 17 months age-group. In the 5 to 17 months age-group (where the malaria vaccine was planned to be subsequently rolled out) the meningitis, malaria, severe malaria and cerebral malaria incidences were 92 (95% CI 25–236), 47,824 (95% CI 45,411–50,333), 1919 (95% CI 1461–2476) and 33 (95% CI 1–181) per 100,000 person-years, respectively. The all-cause mortality was 969 (95% CI 699–1310) per 100,000 person-years.

Conclusion

Incidence estimates of multiple health outcomes are being generated to allow before-after vaccine introduction comparisons that will further characterize the benefit-risk profile of the RTS,S/AS01_E vaccine.

Trial registration: clinicaltrials.gov NCT02374450.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12936-021-03670-w.

Meningococcal carriage 7 years after introduction of a serogroup A meningococcal conjugate vaccine in Burkina Faso: results from four cross-sectional carriage surveys

BACKGROUND

In the first 2 years after a nationwide mass vaccination campaign of 1-29-year-olds with a meningococcal serogroup A conjugate vaccine (MenAfriVac) in Burkina Faso, carriage and disease due to serogroup A Neisseria meningitidis were nearly eliminated. We aimed to assess the long-term effect of MenAfriVac vaccination on meningococcal carriage and herd immunity.

METHODS

We did four cross-sectional studies of meningococcal carriage in people aged 9 months to 36 years in two districts of Burkina Faso between May 2, 2016, and Nov 6, 2017. Demographic information and oropharyngeal swabs were collected. Meningococcal isolates were characterised using whole-genome sequencing.

FINDINGS

Of 14 295 eligible people, 13 758 consented and had specimens collected and laboratory results available, 1035 of whom were meningococcal carriers. Accounting for the complex survey design, prevalence of meningococcal carriage was 7·60% (95% CI 5·67-9·52), including 6·98% (4·86-9·11) non-groupable, 0·48% (0·01-0·95) serogroup W, 0·10% (0·01-0·18) serogroup C, 0·03% (0·00-0·80) serogroup E, and 0% serogroup A. Prevalence ranged from 5·44% (95% CI 4·18-6·69) to 9·14% (6·01-12·27) by district, from 4·67% (2·71-6·64) to 11·17% (6·75-15·59) by round, and from 3·39% (0·00-8·30) to 10·43% (8·08-12·79) by age group. By clonal complex, 822 (88%) of 934 non-groupable isolates were CC192, all 83 (100%) serogroup W isolates were CC11, and nine (69%) of 13 serogroup C isolates were CC10217.

INTERPRETATION

Our results show the continued effect of MenAfriVac on serogroup A meningococcal carriage, for at least 7 years, among vaccinated and unvaccinated cohorts. Carriage prevalence of epidemic-prone serogroup C CC10217 and serogroup W CC11 was low. Continued monitoring of N meningitidis carriage will be crucial to further assess the effect of MenAfriVac and inform the vaccination strategy for future multivalent meningococcal vaccines.

FUNDING

Bill & Melinda Gates Foundation and Gavi, the Vaccine Alliance.

Epidemiological Characteristics of Meningococcal Meningitis (2016 to 2018) Four Years after the Introduction of Serogroup A Meningococcal Conjugate Vaccine in Benin

Objectives. This study aims to study the epidemiological and geographic characteristics of the meningococcal serogroups four years after the introduction of serogroup A meningococcal conjugate vaccine. Methods. This is a prospective, descriptive, analytical study, and it took place from 2016 to 2018. Cerebrospinal fluid (CSF) samples were taken after the identification of meningitis cases. The samples, thus, taken were sent to the laboratory for culture and identification of Neisseria meningitidis in accordance with WHO standards. Results. Eight hundred and ninety-nine bacterial strains were identified, of which 219 were strains of Neisseria meningitidis. The majority of N. meningitidis-positive samples were from male patients (59.8%) with a median age of 4 (IQR: 1–13). Four of N. meningitidis serogroups were identified, namely, serogroups C (6.8%), W (19.6%), X (1.8%), and A (0.5%). Geographically, 92.7% of the identified N. meningitidis serogroups came from patients who lived in the northern region of the country. The departments most concerned were Alibori (N. meningitidis C (66.7%) and N. meningitidis W (20.9%)); Atacora (N. meningitidis W (41.9%), N. meningitidis X (75.0%), and N. meningitidis C (13.3%)); and Borgou (N. meningitidis W (23.3%)). Conclusion. The results of this study showed that there is an emergence of cases of meningococcal of serogroup C four years after the introduction of MenAfricVac in Benin. These results demonstrated the effectiveness of case-by-case surveillance in detecting small changes in the distribution of serogroups that could have important implications for public health strategies in the coming seasons.

The global meningitis genome partnership

Genomic surveillance of bacterial meningitis pathogens is essential for effective disease control globally, enabling identification of emerging and expanding strains and consequent public health interventions. While there has been a rise in the use of whole genome sequencing, this has been driven predominately by a subset of countries with adequate capacity and resources. Global capacity to participate in surveillance needs to be expanded, particularly in low and middle-income countries with high disease burdens. In light of this, the WHO-led collaboration, Defeating Meningitis by 2030 Global Roadmap, has called for the establishment of a Global Meningitis Genome Partnership that links resources for: N. meningitidis (Nm), S. pneumoniae (Sp), H. influenzae (Hi) and S. agalactiae (Sa) to improve worldwide co-ordination of strain identification and tracking. Existing platforms containing relevant genomes include: PubMLST: Nm (31,622), Sp (15,132), Hi (1935), Sa (9026); The Wellcome Sanger Institute: Nm (13,711), Sp (> 24,000), Sa (6200), Hi (1738); and BMGAP: Nm (8785), Hi (2030). A steering group is being established to coordinate the initiative and encourage high-quality data curation. Next steps include: developing guidelines on open-access sharing of genomic data; defining a core set of metadata; and facilitating development of user-friendly interfaces that represent publicly available data.

Evaluation of pneumococcal meningitis clusters in Burkina Faso and implications for potential reactive vaccination

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From 2011 to 2017, Burkina Faso had 20 pneumococcal meningitis clusters of ≥ 5 cases per district/week.

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Clusters had a maximum weekly incidence of 7 cases and a maximum duration of 4 weeks.

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Most clusters occurred prior to 13-valent pneumococcal conjugate vaccine introduction.

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Clusters were caused by a mixture of serotypes, with serotype 1 being most common.

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Due to the limited cluster size and duration, there were no clear indications for reactive vaccination.

Background

To better understand how to prevent and respond to pneumococcal meningitis outbreaks in the meningitis belt, we retrospectively examined Burkina Faso’s case-based meningitis surveillance data for pneumococcal meningitis clusters and assessed potential usefulness of response strategies.

Methods

Demographic and clinical information, and cerebrospinal fluid laboratory results for meningitis cases were collected through nationwide surveillance. Pneumococcal cases were confirmed by culture, polymerase chain reaction (PCR), or latex agglutination; strains were serotyped using PCR. We reviewed data from 2011 to 2017 to identify and describe clusters of ≥ 5 confirmed pneumococcal meningitis cases per week in a single district. We assessed whether identified clusters met the 2016 WHO provisional pneumococcal meningitis outbreak definition: a district with a weekly incidence of >5 suspected meningitis cases/100,000 persons, >60% of confirmed meningitis cases caused by Streptococcus pneumoniae, and >10 confirmed pneumococcal meningitis cases.

Results

Twenty pneumococcal meningitis clusters were identified, with a maximum weekly incidence of 7 cases and a maximum duration of 4 weeks. Most identified clusters (15/20; 75%) occurred before nationwide introduction of 13-valent pneumococcal conjugate vaccine (PCV13) in October 2013. Most cases were due to serotype 1 (74%), 10% were due to PCV13 serotypes besides serotype 1, and 8 clusters had >1 serotype. While 6 identified clusters had a weekly incidence of >5 suspected cases/100,000 and all 20 clusters had >60% of confirmed meningitis cases due to S. pneumoniae, no cluster had >10 confirmed pneumococcal meningitis cases in a single week.

Conclusions

Following PCV13 introduction, pneumococcal meningitis clusters were rarely detected, and none met the WHO provisional pneumococcal outbreak definition. Due to the limited cluster size and duration, there were no clear instances where reactive vaccination could have been useful. More data are needed to inform potential response strategies.

MenAfriNet: A Network Supporting Case-Based Meningitis Surveillance and Vaccine Evaluation in the Meningitis Belt of Africa

Meningococcal meningitis remains a significant public health threat, especially in the African meningitis belt where Neisseria meningitidis serogroup A historically caused large-scale epidemics. With the rollout of a novel meningococcal serogroup A conjugate vaccine (MACV) in the belt, the World Health Organization recommended case-based meningitis surveillance to monitor MACV impact and meningitis epidemiology. In 2014, the MenAfriNet consortium was established to support strategic implementation of case-based meningitis surveillance in 5 key countries: Burkina Faso, Chad, Mali, Niger, and Togo. MenAfriNet aimed to develop a high-quality surveillance network using standardized laboratory and data collection protocols, develop sustainable systems for data management and analysis to monitor MACV impact, and leverage the surveillance platform to perform special studies. We describe the MenAfriNet consortium, its history, strategy, implementation, accomplishments, and challenges.

The Strengthening of Laboratory Systems in the Meningitis Belt to Improve Meningitis Surveillance, 2008-2018: A Partners' Perspective

Laboratories play critical roles in bacterial meningitis disease surveillance in the African meningitis belt, where the highest global burden of meningitis exists. Reinforcement of laboratory capacity ensures rapid detection of meningitis cases and outbreaks and a public health response that is timely, specific, and appropriate. Since 2008, joint efforts to strengthen laboratory capacity by multiple partners, including MenAfriNet, beginning in 2014, have been made in countries within and beyond the meningitis belt. Over the course of 10 years, national reference laboratories were supported in 5 strategically targeted areas: specimen transport systems, laboratory procurement systems, laboratory diagnosis, quality management, and laboratory workforce with substantial gains made in each of these areas. To support the initiative to eliminate meningitis by 2030, continued efforts are needed to strengthen laboratory systems.

Impact of 13-Valent Pneumococcal Conjugate Vaccine on Pneumococcal Meningitis, Burkina Faso, 2016-2017

BACKGROUND

In 2013, Burkina Faso introduced 13-valent pneumococcal conjugate vaccine (PCV13) into the routine childhood immunization program, to be administered to children at 8, 12, and 16 weeks of age. We evaluated the impact of PCV13 on pneumococcal meningitis.

METHODS

Using nationwide surveillance, we gathered demographic/clinical information and cerebrospinal fluid (CSF) results for meningitis cases. Pneumococcal cases were confirmed by culture, polymerase chain reaction (PCR), or latex agglutination; strains were serotyped using PCR. We compared annual incidence (cases per 100 000) 4 years after PCV13's introduction (2017) to average pre-PCV13 incidence (2011-2013). We adjusted incidence for age and proportion of cases with CSF tested at national laboratories.

RESULTS

In 2017, pneumococcal meningitis incidence was 2.7 overall and 10.5 (<1 year), 3.8 (1-4 years), 3.5 (5-14 years), and 1.4 (≥15 years) by age group. Compared to 2011-2013, PCV13-serotype incidence was significantly lower among all age groups, with the greatest decline among children aged <1 year (77%; 95% confidence interval [CI], 65%-84%). Among all ages, the drop in incidence was larger for PCV13 serotypes excluding serotype 1 (79%; 95% CI, 72%-84%) than for serotype 1 (52%; 95% CI, 44%-59%); incidence of non-PCV13 serotypes also declined (53%; 95% CI, 37%-65%). In 2017, 45% of serotyped cases among all ages were serotype 1 and 12% were other PCV13 serotypes.

CONCLUSIONS

In Burkina Faso, meningitis caused by PCV13 serotypes continues to decrease, especially among young children. However, the concurrent decline in non-PCV13 serotypes and short pre-PCV13 observation period complicate evaluation of PCV13's impact. Efforts to improve control of serotype 1, such as switching from a 3 + 0 schedule to a 2 + 1 schedule, may improve overall control of pneumococcal meningitis in this setting.

Methods for rapid diagnosis of meningitis etiology in adults

Infectious meningitis can be caused by viral, bacterial or fungal pathogens. Despite widely available treatments, many types of infectious meningitis are still associated with significant morbidity and mortality. Delay in diagnosis contributes to poor outcomes. Cerebrospinal fluid cultures have been used traditionally but are time intensive and sensitivity is decreased by empiric treatment prior to culture. More rapid techniques such as the cryptococcal lateral flow assay (IMMY), GeneXpert MTB/Rif Ultra (Cepheid) and FilmArray multiplex-PCR (Biofire) are three examples that have drastically changed meningitis diagnostics. This review will discuss a holistic approach to diagnosing bacterial, mycobacterial, viral and fungal meningitis.

Protecting the most vulnerable age group: a review of MenACWY-TT immunogenicity and safety in infants

INTRODUCTION

Neisseria meningitidis causes invasive meningococcal disease (IMD), with the highest incidence observed in infants and young children. Meningococcal serogroups A, B, C, W, X, and Y account for almost all IMD cases worldwide. Available meningococcal vaccines targeting serogroups A, C, W, and Y (MenACWY) include those conjugated to diphtheria toxoid (MenACWY-D), diphtheria protein cross-reactive material 197 (MenACWY-CRM₁₉₇), and tetanus toxoid (MenACWY-TT). MenACWY-TT is indicated for use starting at 6 weeks of age.

AREAS COVERED

This review discusses data from the four primary studies assessing MenACWY-TT safety and immunogenicity in infants, which evaluated a variety of dosing schedules, short-term and long-term outcomes, and impact of coadministration on the immunogenicity of routine childhood vaccines. Remaining gaps in the field are addressed.

EXPERT OPINION

Robust data support the use of MenACWY-TT in infants starting as early as 6 weeks of age. MenACWY-TT was safe and well tolerated in infants, was immunogenic after priming and booster, and demonstrated persistent immunogenicity. Lower persistence for serogroup A relative to other serogroups based on serum bactericidal assays (SBAs) using human complement appears to be a class effect of MenACWY conjugate vaccines. Correlates of protection other than SBA are being explored, including immunologic responses associated with different carrier proteins.

Antibody Persistence at the Population Level 5 Years After Mass Vaccination With Meningococcal Serogroup A Conjugate Vaccine (PsA-TT) in Burkina Faso: Need for a Booster Campaign?

Background

In Burkina Faso, serogroup A meningococcal (NmA) conjugate vaccine (PsA-TT, MenAfriVac) was introduced through a mass campaign in children and adults in December 2010. Similar to a serological survey in 2011, we followed population-level antibody persistence for 5 years after the campaign and estimated time of return to previously-published pre-vaccination levels.

Methods

We conducted 2 cross-sectional surveys in 2013 and early 2016, including representative samples (N = 600) of the general population of Bobo-Dioulasso, Burkina Faso. Serum bactericidal antibody titers (rabbit complement) were measured against NmA reference strain F8236 (SBA-ref), NmA strain 3125 (SBA-3125), and NmA-specific immunoglobulin G (IgG) concentrations.

Results

During the 2016 survey, in different age groups between 6 and 29 years, the relative changes in geometric means compared to 2011 values were greater among younger age groups. They were between -87% and -43% for SBA-ref; -99% and -78% for SBA-3125; and -89% and -63% for IgG. In linear extrapolation of age-specific geometric means from 2013 to 2016, among children aged 1-4 years at the time of the PsA-TT campaign, a return to pre-vaccination levels should be expected after 12, 8, and 6 years, respectively, according to SBA-ref, SBA-3125, and IgG. Among older individuals, complete return to baseline is expected at the earliest after 11 years (SBA-ref and SBA-3125) or 9 years (IgG).

Conclusions

Based on SBA-3125, a booster campaign after 8 years would be required to sustain direct immune protection for children aged 1-4 years during the PsA-TT campaign. Antibodies persisted longer in older age groups.

Health workers' perceptions and challenges in implementing meningococcal serogroup a conjugate vaccine in the routine childhood immunization schedule in Burkina Faso

BACKGROUND

Meningococcal serogroup A conjugate vaccine (MACV) was introduced in 2017 into the routine childhood immunization schedule (at 15-18 months of age) in Burkina Faso to help reduce meningococcal meningitis burden. MACV was scheduled to be co-administered with the second dose of measles-containing vaccine (MCV2), a vaccine already in the national schedule. One year following the introduction of MACV, an assessment was conducted to qualitatively examine health workers' perceptions of MACV introduction, identify barriers to uptake, and explore opportunities to improve coverage.

METHODS

Twelve in-depth interviews were conducted with different cadres of health workers in four purposively selected districts in Burkina Faso. Districts were selected to include urban and rural areas as well as high and low MCV2 coverage areas. Respondents included health workers at the following levels: regional health managers (n = 4), district health managers (n = 4), and frontline healthcare providers (n = 4). All interviews were recorded, transcribed, and thematically analyzed using qualitative content analysis.

RESULTS

Four themes emerged around supply and health systems barriers, demand-related barriers, specific challenges related to MACV and MCV2 co-administration, and motivations and efforts to improve vaccination coverage. Supply and health systems barriers included aging cold chain equipment, staff shortages, overworked and poorly trained staff, insufficient supplies and financial resources, and challenges with implementing community outreach activities. Health workers largely viewed MACV introduction as a source of motivation for caregivers to bring their children for the 15- to 18-month visit. However, they also pointed to demand barriers, including cultural practices that sometimes discourage vaccination, misconceptions about vaccines, and religious beliefs. Challenges in co-administering MACV and MCV2 were mainly related to reluctance among health workers to open multi-dose vials unless enough children were present to avoid wastage.

CONCLUSIONS

To improve effective administration of vaccines in the second-year of life, adequate operational and programmatic planning, training, communication, and monitoring are necessary. Moreover, clear policy communication is needed to help ensure that health workers do not refrain from opening multi-dose vials for small numbers of children.

Optimizing Laboratory Diagnostic Services for Infectious Meningitis in the Meningitis Belt of sub-Saharan Africa

For longer than a century, the "meningitis belt" of sub-Saharan Africa has experienced the largest-ever global meningitis epidemic. Whereas HIV-associated immunosuppression drives higher susceptibility to environmental infectious organisms with tropism for the central nervous system (CNS), most diagnostic laboratories in the belt stick to N. meningitidis, H. influenzae, and S. pneumoniae. Cryptococcus neoformans has been the leading cause of death (incidence, 89%; death, 75%). To establish whether diagnostic services target geographically important pathogens, there is a need to know the current spectrum of etiology. Given Africa's agro-silvo-pastoralism, the One Health diagnostic approach is recommended. Considering  multipathogen detection capacity, needed speed for corticosteroid therapy decision, and susceptibility/resistance to antimicrobials with improved CNS penetration, proposed laboratory categorization will help neurologists to choose suitable services.

Implementation of Case-Based Surveillance and Real-time Polymerase Chain Reaction to Monitor Bacterial Meningitis Pathogens in Chad

BACKGROUND

Meningococcal serogroup A conjugate vaccine (MACV) was introduced in Chad during 2011-2012. Meningitis surveillance has been conducted nationwide since 2003, with case-based surveillance (CBS) in select districts from 2012. In 2016, the MenAfriNet consortium supported Chad to implement CBS in 4 additional districts and real-time polymerase chain reaction (rt-PCR) at the national reference laboratory (NRL) to improve pathogen detection. We describe analysis of bacterial meningitis cases during 3 periods: pre-MACV (2010-2012), pre-MenAfriNet (2013-2015), and post-MenAfriNet (2016-2018).

METHODS

National surveillance targeted meningitis cases caused by Neisseria meningitidis, Haemophilus influenzae, and Streptococcus pneumoniae. Cerebrospinal fluid specimens, inoculated trans-isolate media, and/or isolates from suspected meningitis cases were tested via culture, latex, and/or rt-PCR; confirmed bacterial meningitis was defined by a positive result on any test. We calculated proportion of suspected cases with a specimen received by period, and proportion of specimens with a bacterial meningitis pathogen identified, by period, pathogen, and test.

RESULTS

The NRL received specimens for 6.8% (876/12813), 46.4% (316/681), and 79.1% (787/995) of suspected meningitis cases in 2010-2012, 2013-2015, and 2016-2018, respectively, with a bacterial meningitis pathogen detected in 33.6% (294/876), 27.8% (88/316), and 33.2% (261/787) of tested specimens. The number of N. meningitidis serogroup A (NmA) among confirmed bacterial meningitis cases decreased from 254 (86.4%) during 2010-2012 to 2 (2.3%) during 2013-2015, with zero NmA cases detected after 2014. In contrast, proportional and absolute increases were seen between 2010-2012, 2013-2015, and 2016-2018 in cases caused by S. pneumoniae (5.1% [15/294], 65.9% [58/88], and 52.1% [136/261]), NmX (0.7% [2/294], 1.1% [1/88], and 22.2% [58/261]), and Hib (0.3% [1/294], 11.4% [10/88], and 14.9% [39/261]). Of specimens received at the NRL, proportions tested during the 3 periods were 47.7% (418), 53.2% (168), and 9.0% (71) by latex; 81.4% (713), 98.4% (311), and 93.9% (739) by culture; and 0.0% (0), 0.0% (0), and 90.5% (712) by rt-PCR, respectively. During the post-MenAfriNet period (2016-2018), 86.1% (678) of confirmed cases were tested by both culture and rt-PCR, with 12.5% (85) and 32.4% (220) positive by culture and rt-PCR, respectively.

CONCLUSIONS

CBS implementation was associated with increased specimen referral. Increased detection of non-NmA cases could reflect changes in incidence or increased sensitivity of case detection with rt-PCR. Continued surveillance with the use of rt-PCR to monitor changing epidemiology could inform the development of effective vaccination strategies.

Development and Implementation of a Cloud-Based Meningitis Surveillance and Specimen Tracking System in Burkina Faso, 2018

Nationwide case-based meningitis surveillance was established in Burkina Faso following the introduction of meningococcal serogroup A conjugate vaccine in 2010. However, timely tracking and arrival of cerebrospinal fluid specimens for confirmation at national reference laboratories remained suboptimal. To better understand this gap and identify bottlenecks, the Burkina Faso Ministry of Health, along with key partners, developed and implemented a cloud-based System for Tracking Epidemiological Data and Laboratory Specimens (STELAB), allowing for timely nationwide data reporting and specimen tracking using barcodes. STELAB was adapted to Burkina Faso's infrastructure to ensure suitability, functionality, flexibility, and sustainability. We describe the design, development, and implementation of STELAB. In addition, we discuss strategies used to promote sustainability, lessons learned during the first year of implementation, and future directions. STELAB's novel design and country-driven approach has the potential to achieve sustainable real-time data reporting and specimen tracking for the first time in sub-Saharan Africa.

Future Directions for Meningitis Surveillance and Vaccine Evaluation in the Meningitis Belt of Sub-Saharan Africa

In sub-Saharan Africa, bacterial meningitis remains a significant public health problem, especially in the countries of the meningitis belt, where Neisseria meningitidis serogroup A historically caused large-scale epidemics. In 2014, MenAfriNet was established as a consortium of partners supporting strategic implementation of case-based meningitis surveillance to monitor meningitis epidemiology and impact of meningococcal serogroup A conjugate vaccine (MACV). MenAfriNet improved data quality through use of standardized tools, procedures, and laboratory diagnostics. MenAfriNet surveillance and study data provided evidence of ongoing MACV impact, characterized the burden of non-serogroup A meningococcal disease (including the emergence of a new epidemic clone of serogroup C), and documented the impact of pneumococcal conjugate vaccine. New vaccines and schedules have been proposed for future implementation to address the remaining burden of meningitis. To support the goals of "Defeating Meningitis by 2030," MenAfriNet will continue to strengthen surveillance and support research and modeling to monitor the impact of these programs on meningitis burden in sub-Saharan Africa.

Status of the Rollout of the Meningococcal Serogroup A Conjugate Vaccine in African Meningitis Belt Countries in 2018

BACKGROUND

A novel meningococcal serogroup A conjugate vaccine (MACV [MenAfriVac]) was developed as part of efforts to prevent frequent meningitis outbreaks in the African meningitis belt. The MACV was first used widely and with great success, beginning in December 2010, during initial deployment in Burkina Faso, Mali, and Niger. Since then, MACV rollout has continued in other countries in the meningitis belt through mass preventive campaigns and, more recently, introduction into routine childhood immunization programs associated with extended catch-up vaccinations.

METHODS

We reviewed country reports on MACV campaigns and routine immunization data reported to the World Health Organization (WHO) Regional Office for Africa from 2010 to 2018, as well as country plans for MACV introduction into routine immunization programs.

RESULTS

By the end of 2018, 304 894 726 persons in 22 of 26 meningitis belt countries had received MACV through mass preventive campaigns targeting individuals aged 1-29 years. Eight of these countries have introduced MACV into their national routine immunization programs, including 7 with catch-up vaccinations for birth cohorts born after the initial rollout. The Central African Republic introduced MACV into its routine immunization program immediately after the mass 1- to 29-year-old vaccinations in 2017 so no catch-up was needed.

CONCLUSIONS

From 2010 to 2018, successful rollout of MACV has been recorded in 22 countries through mass preventive campaigns followed by introduction into routine immunization programs in 8 of these countries. Efforts continue to complete MACV introduction in the remaining meningitis belt countries to ensure long-term herd protection.

Epidemiology of Bacterial Meningitis in the Nine Years Since Meningococcal Serogroup A Conjugate Vaccine Introduction, Niger, 2010-2018

BACKGROUND

In 2010, Niger and other meningitis belt countries introduced a meningococcal serogroup A conjugate vaccine (MACV). We describe the epidemiology of bacterial meningitis in Niger from 2010 to 2018.

METHODS

Suspected and confirmed meningitis cases from January 1, 2010 to July 15, 2018 were obtained from national aggregate and laboratory surveillance. Cerebrospinal fluid specimens were analyzed by culture and/or polymerase chain reaction. Annual incidence was calculated as cases per 100 000 population. Selected isolates obtained during 2016-2017 were characterized by whole-genome sequencing.

RESULTS

Of the 21 142 suspected cases of meningitis, 5590 were confirmed: Neisseria meningitidis ([Nm] 85%), Streptococcus pneumoniae ([Sp] 13%), and Haemophilus influenzae ([Hi] 2%). No NmA cases occurred after 2011. Annual incidence per 100 000 population was more dynamic for Nm (0.06-7.71) than for Sp (0.18-0.70) and Hi (0.01-0.23). The predominant Nm serogroups varied over time (NmW in 2010-2011, NmC in 2015-2018, and both NmC and NmX in 2017-2018). Meningococcal meningitis incidence was highest in the regions of Niamey, Tillabery, Dosso, Tahoua, and Maradi. The NmW isolates were clonal complex (CC)11, NmX were CC181, and NmC were CC10217.

CONCLUSIONS

After MACV introduction, we observed an absence of NmA, the emergence and continuing burden of NmC, and an increase in NmX. Niger's dynamic Nm serogroup distribution highlights the need for strong surveillance programs to inform vaccine policy.

Bacterial Meningitis Epidemiology in Five Countries in the Meningitis Belt of Sub-Saharan Africa, 2015-2017

BACKGROUND

The MenAfriNet Consortium supports strategic implementation of case-based meningitis surveillance in key high-risk countries of the African meningitis belt: Burkina Faso, Chad, Mali, Niger, and Togo. We describe bacterial meningitis epidemiology in these 5 countries in 2015-2017.

METHODS

Case-based meningitis surveillance collects case-level demographic and clinical information and cerebrospinal fluid (CSF) laboratory results. Neisseria meningitidis, Streptococcus pneumoniae, or Haemophilus influenzae cases were confirmed and N. meningitidis/H. influenzae were serogrouped/serotyped by real-time polymerase chain reaction, culture, or latex agglutination. We calculated annual incidence in participating districts in each country in cases/100 000 population.

RESULTS

From 2015-2017, 18 262 suspected meningitis cases were reported; 92% had a CSF specimen available, of which 26% were confirmed as N. meningitidis (n = 2433; 56%), S. pneumoniae (n = 1758; 40%), or H. influenzae (n = 180; 4%). Average annual incidences for N. meningitidis, S. pneumoniae, and H. influenzae, respectively, were 7.5, 2.5, and 0.3. N. meningitidis incidence was 1.5 in Burkina Faso, 2.7 in Chad, 0.4 in Mali, 14.7 in Niger, and 12.5 in Togo. Several outbreaks occurred: NmC in Niger in 2015-2017, NmC in Mali in 2016, and NmW in Togo in 2016-2017. Of N. meningitidis cases, 53% were NmC, 30% NmW, and 13% NmX. Five NmA cases were reported (Burkina Faso, 2015). NmX increased from 0.6% of N. meningitidis cases in 2015 to 27% in 2017.

CONCLUSIONS

Although bacterial meningitis epidemiology varied widely by country, NmC and NmW caused several outbreaks, NmX increased although was not associated with outbreaks, and overall NmA incidence remained low. An effective low-cost multivalent meningococcal conjugate vaccine could help further control meningococcal meningitis in the region.

Improving Case-Based Meningitis Surveillance in 5 Countries in the Meningitis Belt of Sub-Saharan Africa, 2015–2017

Background

The MenAfriNet consortium was established in 2014 to support implementation of case-based meningitis surveillance in 5 countries in the meningitis belt of sub-Saharan Africa: Burkina Faso, Chad, Mali, Niger, and Togo. Assessing surveillance performance is critical for interpretation of the collected data and implementation of future surveillance-strengthening initiatives.

Methods

Detailed epidemiologic and laboratory data were collected on suspected meningitis cases through case-based meningitis surveillance in participating districts in 5 countries. Performance of case-based surveillance was evaluated through sensitivity of case ascertainment in case-based versus aggregate meningitis surveillance and an analysis of surveillance indicators.

Results

From 2015 to 2017, 18 262 suspected meningitis cases were identified through case-based surveillance and 16 262 were identified through aggregate surveillance, for a case ascertainment sensitivity of 112.3%. Among suspected cases, 16 885 (92.5%) had a cerebrospinal fluid (CSF) specimen collected, 13 625 (80.7%) of which were received at a national reference laboratory. Among these, 13 439 (98.6%) underwent confirmatory testing, and, of those tested, 4371 (32.5%) were confirmed for a bacterial pathogen.

Conclusions

Overall strong performance for case ascertainment, CSF collection, and laboratory confirmation provide evidence for the quality of MenAfriNet case-based surveillance in evaluating epidemiologic trends and informing future vaccination strategies.

Bacterial meningitis in Sudanese children; critical evaluation of the clinical decision using clinical prediction rules

BACKGROUND

Sudan falls in the meningitis belt where most global cases of bacterial meningitis are reported. Highly accurate decision support tools have been developed by international specialized societies to guide the diagnosis and limit unnecessary hospital admissions and prolonged antibiotic use that have been frequently reported from countries around the world. The goals of this study are to critically evaluate the clinical decision of bacterial meningitis in children in Sudan using clinical prediction rules and to identify the current bacterial aetiology.

METHODS

This cross-sectional hospital-based study was conducted in October to July of 2010 in a major referral pediatric hospital in Khartoum, Sudan. Febrile children age 1 day to 15 years who were provisionally diagnosed as having meningitis on admission were included (n = 503). Cerebrospinal fluid (CSF) specimens were obtained from all patients while clinical and demographic data were available for only 404. Conventional laboratory investigations were performed. The clinical decision was evaluated by the International Classification of Diseases-Clinical Modification code 320.9 and the Bacterial Meningitis Score. Ethical clearance and permissions were obtained.

RESULTS

Out of 503 provisionally diagnosed bacterial meningitis patients, the final clinical confirmation was assigned to 55.9%. When codes were applied; 5.7% (23/404) with CSF pleocytosis were re-classified as High Risk for bacterial meningitis and 1.5% (6/404) with confirmed bacterial aetiology as Proven Bacterial Meningitis. Neisseria meningitidis was identified in 0.7% (3/404) and Streptococcus pneumoniae in another 0.7%. Typical laboratory findings (i.e. CSF pleocytosis and/or low glucose and high protein concentrations, Gram positive or Gram negative diplococcic, positive bacterial culture) were seen in 5 (83%). Clinically, patients showed fever, seizures, chills, headache, vomiting, stiff neck and bulging fontanelle. All confirmed cases were less than 5 years old and were admitted in summer. All patients were prescribed with antibiotics; they were all recovered and discharged.

CONCLUSIONS

Bacterial meningitis is over-diagnosed in hospitals in Khartoum therefore clinical prediction rules must be adopted and applied to guide the clinical decision. The sole bacterial aetiology in this selected group of Sudanese children remain N. meningitidis and S. pneumoniae, but with significant decrease in prevalence. Some cases showed atypical clinical and laboratory findings.

[Genotypes of Neisseria meningitidis isolates in patients with meningococcal meningitis in Paraguay, 1996-2015Genótipos de Neisseria meningitidis isolados de pacientes com doença meningocócica no Paraguai, 1996-2015]

Objetivo

Describir las características fenotípicas y genotípicas de cepas de Neisseria meningitidis aisladas de enfermedad meningocócica en Paraguay entre 1996 y 2015.

Métodos

Se estudiaron por métodos microbiológicos convencionales y técnicas moleculares 114 aislamientos de N. meningitidis y 12 muestras clínicas sin aislamiento confirmadas por reacción en cadena de la polimerasa (PCR) que fueron remitidas por los diferentes centros centinelas y centros colaboradores de Paraguay.

Resultados

El grupo de edad más afectado fue el de menores de 1 año (19,0%), seguido por el de 1 a 5 años (17,5%). Un mayor porcentaje de las cepas se aisló de casos de meningitis (81,7%) y el serogrupo B se encontró en 60,3% de los casos. Los fenotipos más frecuentes fueron B:4:P1.14 (16,0%), B:15:P1.5, C:NT:NST y W:NT:P1.2 (10,5%), respectivamente. Los complejos clonales prevalentes fueron ST-11/ET37 complex 29,6% (8/27) con predominio del serogrupo W (6/8), ST-35 complex 18,5% (5/27) en el serogrupo B (4/4), y ST-32/ET5 complex 14,8% (4/16) en el serogrupo B (5/5).

Conclusiones

En Paraguay la enfermedad meningocócica es relativamente infrecuente. Los análisis de distribución de serogrupo muestran que el más frecuente es el B y en los últimos dos años aumentaron los casos de enfermedad meningocócica por C y W. Los complejos clonales encontrados se correlacionan con los hallados en la región del Cono Sur. Debido al alto nivel de virulencia de N. meningitidis, su vigilancia debe constituir una prioridad estratégica de los sistemas de salud pública nacionales y regionales para prevenir brotes epidémicos y apoyar la toma de decisiones en salud pública.

Combined testing for herpes simplex virus and Mycobacterium tuberculosis DNA in cerebrospinal fluid of patients with aseptic meningitis in Burkina Faso, West Africa

BACKGROUND

Little is known about the involvement of herpes simplex virus (HSV) or Mycobacterium tuberculosis (MTB) as potentially curable causes of central nervous system (CNS) infections in sub-Saharan Africa.

OBJECTIVE

In this study, we developed a PCR assay dedicated to simultaneous testing of HSV1/HSV2 and MTB in Burkina Faso, a country where HSV is neglected as a cause of CNS infection and where TB prevalence is high.

METHODS

A consensus HSV1/HSV2 set of primers and probe were designed and combined to primers and probe targeting the IS6110 repetitive insertion sequence of MTB. Analytical performances of the assay were evaluated on reference materials. Cerebrospinal fluid (CSF) collected from subjects with aseptic meningitis was tested for HSV1/HSV2 and MTB DNA.

RESULTS

The UL29 gene was chosen as a highly conserved region targeted by the HSV1/HSV2 nucleic acid test. The lower limits of detection were estimated to be 2.45 copies/µL for HSV1, 1.72 copies/µL for HSV2, and 2.54 IS6110 copies per µL for MTB. The PCR was used in 202 CSF collected from subjects suspected of aseptic meningitis. Five samples (2.46%) tested positive, including two children positive for HSV1 (0.99%) and three adults tested positive for MTB (1.47%).

CONCLUSION

Using an in-house real-time PCR assay, we showed that both HSV and MTB are etiologic pathogens contributing to aseptic meningitis in Burkina Faso. This molecular test may have clinical utility for early diagnosis for those treatable CNS infections.

Cross-Reactive Bactericidal Antimeningococcal Antibodies Can Be Isolated From Convalescing Invasive Meningococcal Disease Patients Using Reverse Vaccinology 2.0

The threat from invasive meningococcal disease (IMD) remains a serious source of concern despite the licensure and availability of vaccines. A limitation of current serogroup B vaccines is the breadth of coverage afforded, resulting from the capacity for extensive variation of the meningococcus and its huge potential for the generation of further diversity. Thus, the continuous search for candidate antigens that will compose supplementary or replacement vaccines is mandated. Here, we describe successful efforts to utilize the reverse vaccinology 2.0 approach to identify novel functional meningococcal antigens. In this study, eight broadly cross-reactive sequence-specific antimeningococcal human monoclonal antibodies (hmAbs) were cloned from 4 ml of blood taken from a 7-month-old sufferer of IMD. Three of these hmAbs possessed human complement-dependent bactericidal activity against meningococcal serogroup B strains of disparate PorA and 4CMenB antigen sequence types, strongly suggesting that the target(s) of these bactericidal hmAbs are not PorA (the immunodominant meningococcal antigen), factor-H binding protein, or other components of current meningococcal vaccines. Reactivity of the bactericidal hmAbs was confirmed to a single ca. 35 kDa protein in western blots. Unequivocal identification of this antigen is currently ongoing. Collectively, our results provide proof-of-principle for the use of reverse vaccinology 2.0 as a powerful tool in the search for alternative meningococcal vaccine candidate antigens.

Early impact of 13-valent pneumococcal conjugate vaccine on pneumococcal meningitis-Burkina Faso, 2014-2015

OBJECTIVES

We evaluate early impact of 13-valent pneumococcal conjugate vaccine (PCV13) on pneumococcal meningitis in Burkina Faso.

METHODS

Nationwide surveillance gathered demographic/clinical information and cerebrospinal fluid (CSF) results for meningitis cases. Pneumococcal cases were confirmed by culture, polymerase chain reaction (PCR), or latex agglutination, and strains serotyped using PCR. We compared incidence (cases per 100,000) in the early post-PCV13 period (2014 and 2015) to average pre-PCV13 incidence (2011-2013).

RESULTS

In 2015, age-specific pneumococcal meningitis incidences were 8.7 (<1 year), 2.4 (1-4 years), 6.5 (5-14 years), and 2.6 (≥15 years). Compared to 2011-2013, PCV13-serotype incidence among all ages decreased by 32% (95%CI: 23%-39%), with significant decreases among children aged <1 year (76%; 95%CI: 64%-84%) and 1-4 years (58%, 95%CI: 40%-71%). Among all ages, incidence of PCV13 serotypes besides serotype 1 decreased (68%; 95%CI: 59%-75%), but serotype 1 incidence did not. Incidence of non-PCV13 serotypes also decreased (47%; 95%CI: 29%-60%). Among children aged <1 year, serotypes 12F/12A/12B/44/46 (17%), 1 (12%), and 5 (10%) predominated.

CONCLUSIONS

Following PCV13 introduction, PCV13-serotype meningitis incidence in young children significantly decreased. PCV13 impact on serotype 1 and disease in older children and adults requires continued monitoring.