Outcome of meningitis caused by Streptococcus pneumoniae and Haemophilus influenzae type b in children in The Gambia

Clinical Picture and Risk Factors for Poor Outcome in Streptococcus pneumoniae Meningitis of Childhood on Three Continents

BACKGROUND

Streptococcus pneumoniae meningitis (SpM) remains a major health burden worldwide, particularly in low- and middle-income countries. Identifying the patients at highest risk for mortality and disabling sequelae may reveal potentially avoidable predisposing factors and identify patients most in need of intensive care. We searched for factors that do not require laboratory facilities.

METHODS

This study was a secondary analysis of prospectively collected data from 5 clinical trials of childhood bacterial meningitis on 3 continents between 1984 and 2017. SpM cases were analyzed by study site and predictors for poor outcome (death or severe sequelae) were identified from the whole series, Latin America and Angola.

RESULTS

Among a total of 1575 children (age range: 2 months to 15 years), 505 cases were due to pneumococci. Compared to other etiologies, SpM doubled the death rate (33% vs. 17%) and tripled poor outcome (15% vs. 6%). In SpM, Glasgow Coma Score <13 [odds ratio (OR): 4.73] and previous antibiotics in Angola (OR: 1.70) were independent predictors for death. Predictors for poor outcome were age <1 year (OR: 2.41) and Glasgow Coma Score <13 (OR: 6.39) in the whole series, seizures in Latin America (OR: 3.98) and previous antibiotics in Angola (OR: 1.91). Angolan children had a 17-fold increased risk for poor outcome when compared with Finnish children ( P = 0.011).

CONCLUSIONS

Our study proved the severity of SpM when compared with other etiologies. The outcome was especially poor in Angola. Most patients at risk for poor outcome are easily identified by clinical factors on admission.

Invasive Haemophilus influenzae Infections after 3 Decades of Hib Protein Conjugate Vaccine Use

Haemophilus influenzae serotype b (Hib) was previously the most common cause of bacterial meningitis and an important etiologic agent of pneumonia in children aged <5 years. Its major virulence factor is the polyribosyl ribitol phosphate (PRP) polysaccharide capsule. In the 1980s, PRP-protein conjugate Hib vaccines were developed and are now included in almost all national immunization programs, achieving a sustained decline in invasive Hib infections. However, invasive Hib disease has not yet been eliminated in countries with low vaccine coverage, and sporadic outbreaks of Hib infection still occur occasionally in countries with high vaccine coverage. Over the past 2 decades, other capsulated serotypes have been recognized increasingly as causing invasive infections. H. influenzae serotype a (Hia) is now a major cause of invasive infection in Indigenous communities of North America, prompting a possible requirement for an Hia conjugate vaccine. H. influenzae serotypes e and f are now more common than serotype b in Europe. Significant year-to-year increases in nontypeable H. influenzae invasive infections have occurred in many regions of the world. Invasive H. influenzae infections are now seen predominantly in patients at the extremes of life and those with underlying comorbidities. This review provides a comprehensive and critical overview of the current global epidemiology of invasive H. influenzae infections in different geographic regions of the world. It discusses those now at risk of invasive Hib disease, describes the emergence of other severe invasive H. influenzae infections, and emphasizes the importance of long-term, comprehensive, clinical and microbiologic surveillance to monitor a vaccine's impact.

Hospital-based sentinel surveillance for bacterial meningitis in under-five children prior to the introduction of the PCV13 in India

INTRODUCTION

A hospital-based sentinel surveillance network for bacterial meningitis was established in India to estimate the burden of bacterial meningitis, and the proportion of major vaccine-preventable causative organisms. This report summarises the findings of the surveillance conducted between March 2012, and September 2016 in eleven hospitals.

METHODS

We enrolled eligible children with bacterial meningitis in the age group of one to 59 months. CSF samples were collected and processed for biochemistry, culture, latex agglutination, and real-time PCR. Pneumococcal isolates were serotyped and tested for antimicrobial susceptibility.

RESULTS

Among 12 941 enrolled suspected meningitis cases, 586 (4.5%) were laboratory confirmed. S. pneumoniae (74.2%) was the most commonly detected pathogen, followed by H. influenzae (22.2%), and N. meningitidis (3.6%). Overall 58.1% of confirmed bacterial meningitis cases were children aged between one, and 11 months. H. influenzae meningitis cases had a high (12.3%) case fatality rate. The serotypes covered in PCV13 caused 72% pneumococcal infections, and the most common serotypes were 14 (18.3%), 6B (12.7%) and 19F (9.9%). Non-susceptibility to penicillin was 57%. Forty-five (43.7%) isolates exhibited multidrug resistance, of which 37 were PCV13 serotype isolates.

CONCLUSIONS

The results are representative of the burden of bacterial meningitis among under-five children in India. The findings were useful in rolling out PCV in the National Immunization Program. The non-susceptibility to penicillin and multidrug resistance was an important observation. Timely expansion of PCV across India will significantly reduce the burden of antimicrobial resistance. Continued surveillance is needed to understand the trend after PCV expansion in India.

Pneumococcal vaccine implementation in the African meningitis belt countries: the emerging need for alternative strategies

Introduction: Besides meningococcal disease, the African meningitis belt (AMB) region is also affected by pneumococcal disease. Most AMB countries have introduced pneumococcal conjugate vaccines (PCV) following a schedule of three primary doses without a booster or a catch-up campaign. PCV is expected to help control pneumococcal disease through both direct and indirect effects. Whether and how fast this will be achieved greatly depends on implementation strategies. Pre-PCV data from the AMB indicate high carriage rates of the pneumococcus, not only in infants but also in older children, and a risk of disease and death that spans lifetime. Post-PCV data highlight the protection of vaccinated children, but pneumococcal transmission remains important, resulting in a lack of indirect protection for unvaccinated persons.Areas covered: A non-systematic literature review focused on AMB countries. Relevant search terms were used in PubMed, and selected studies before and after PCV introduction were summarized narratively to appraise the suitability of current PCV programmatic strategies.Expert opinion: The current implementation strategy of PCV in the AMB appears suboptimal regarding the generation of indirect protection. We propose and discuss alternative programmatic strategies, including the implementation of broader age group mass campaigns, to accelerate disease control in this high transmission setting.

The Impact and Burden of Neurological Sequelae Following Bacterial Meningitis: A Narrative Review

The burden, impact, and social and economic costs of neurological sequelae following meningitis can be devastating to patients, families and communities. An acute inflammation of the brain and spinal cord, meningitis results in high mortality rates, with over 2.5 million new cases of bacterial meningitis and over 236,000 deaths worldwide in 2019 alone. Up to 30% of survivors have some type of neurological or neuro-behavioural sequelae. These include seizures, hearing and vision loss, cognitive impairment, neuromotor disability and memory or behaviour changes. Few studies have documented the long-term (greater than five years) consequences or have parsed out whether the age at time of meningitis contributes to poor outcome. Knowledge of the socioeconomic impact and demand for medical follow-up services among these patients and their caregivers is also lacking, especially in low- and middle-income countries (LMICs). Within resource-limited settings, the costs incurred by patients and their families can be very high. This review summarises the available evidence to better understand the impact and burden of the neurological sequelae and disabling consequences of bacterial meningitis, with particular focus on identifying existing gaps in LMICs.

Long Term Impact of Conjugate Vaccines on Haemophilus influenzae Meningitis: Narrative Review

H. influenzae serotype b (Hib) used to be the commonest cause of bacterial meningitis in young children. The widespread use of Hib conjugate vaccine has profoundly altered the epidemiology of H. influenzae meningitis. This short review reports on the spectrum of H. influenzae meningitis thirty years after Hib conjugate vaccine was first introduced into a National Immunization Program (NIP). Hib meningitis is now uncommon, but meningitis caused by other capsulated serotypes of H. influenzae and non-typeable strains (NTHi) should be considered. H. influenzae serotype a (Hia) has emerged as a significant cause of meningitis in Indigenous children in North America, which may necessitate a Hia conjugate vaccine. Cases of Hie, Hif, and NTHi meningitis are predominantly seen in young children and less common in older age groups. This short review reports on the spectrum of H. influenzae meningitis thirty years after Hib conjugate vaccine was first introduced into a NIP.

Association of basic vaccination with cognitive and learning ability among children: insights from the India Human Development Survey, 2004-05 and 2011-12

Basic vaccination is important to protect children from infectious diseases and illnesses. Adequate levels of vaccination coverage reduce the morbidity and mortality burden among children and promote their physical and mental development. This study aimed to assess the association between basic childhood vaccination and the cognitive and learning ability of school children in India. Nationally representative follow-up data on 6183 children from the Indian Human Development Surveys conducted in 2004-05 and 2011-12 (IHDS I & II) were analysed. Children aged 8-10 years who had received all basic vaccines by the age 12 months performed better in a maths test than partially vaccinated or unvaccinated children (OR: 1.87, 95% CI: 1.48, 2.35). Similarly, fully vaccinated children performed better in writing tasks than partially vaccinated or unvaccinated children (OR: 1.77, 95% CI: 1.44, 2.18). Likewise, fully vaccinated children had better reading skills than fully unvaccinated children (OR: 1.60, 95% CI: 1.23, 2.09). The results suggest that enhancing child vaccination coverage can have significant benefits beyond health and can potentially improve the long-term educational outcomes of children.

Etiology of Bacterial Meningitis Among Children <5 Years Old in Côte d'Ivoire: Findings of Hospital-based Surveillance Before and After Pneumococcal Conjugate Vaccine Introduction

Background

Bacterial meningitis remains a major disease affecting children in Côte d’Ivoire. Thus, with support from the World Health Organization (WHO), Côte d’Ivoire has implemented pediatric bacterial meningitis (PBM) surveillance at 2 sentinel hospitals in Abidjan, targeting the main causes of PBM: Streptococcus pneumoniae (pneumococcus), Haemophilus influenzae, and Neisseria meningitidis (meningococcus). Herein we describe the epidemiological characteristics of PBM observed in Côte d’Ivoire during 2010–2016.

Methods

Cerebrospinal fluid (CSF) was collected from children aged <5 years admitted to the Abobo General Hospital or University Hospital Center Yopougon with suspected meningitis. Microbiology and polymerase chain reaction (PCR) techniques were used to detect the presence of pathogens in CSF. Where possible, serotyping/grouping was performed to determine the specific causative agents.

Results

Overall, 2762 cases of suspected meningitis were reported, with CSF from 39.2% (1083/2762) of patients analyzed at the WHO regional reference laboratory in The Gambia. In total, 82 (3.0% [82/2762]) CSF samples were positive for bacterial meningitis. Pneumococcus was the main pathogen responsible for PBM, accounting for 69.5% (52/82) of positive cases. Pneumococcal conjugate vaccine serotypes 5, 18C, 19F, and 6A/B were identified post–vaccine introduction. Emergence of H. influenzae nontypeable meningitis was observed after H. influenzae type b vaccine introduction.

Conclusions

Despite widespread use and high coverage of conjugate vaccines, pneumococcal vaccine serotypes and H. influenzae type b remain associated with bacterial meningitis among children aged <5 years in Côte d’Ivoire. This reinforces the need for enhanced surveillance for vaccine-preventable diseases to determine the prevalence of bacterial meningitis and vaccine impact across the country.

Declines in Pediatric Bacterial Meningitis in the Republic of Benin Following Introduction of Pneumococcal Conjugate Vaccine: Epidemiological and Etiological Findings, 2011-2016

BACKGROUND

Pediatric bacterial meningitis (PBM) remains an important cause of disease in children in Africa. We describe findings from sentinel site bacterial meningitis surveillance in children <5 years of age in the Republic of Benin, 2011-2016.

METHODS

Cerebrospinal fluid (CSF) was collected from children admitted to Parakou, Natitingou, and Tanguieta sentinel hospitals with suspected meningitis. Identification of Streptococcus pneumoniae (pneumococcus), Haemophilus influenzae, and Neisseria meningitidis (meningococcus) was performed by rapid diagnostic tests, microbiological culture, and/or polymerase chain reaction; where possible, serotyping/grouping was performed.

RESULTS

A total of 10 919 suspected cases of meningitis were admitted to the sentinel hospitals. Most patients were 0-11 months old (4863 [44.5%]) and there were 542 (5.0%) in-hospital deaths. Overall, 4168 CSF samples were screened for pathogens and a total of 194 (4.7%) PBM cases were confirmed, predominantly caused by pneumococcus (98 [50.5%]). Following pneumococcal conjugate vaccine (PCV) introduction in 2011, annual suspected meningitis cases and deaths (case fatality rate) progressively declined from 2534 to 1359 and from 164 (6.5%) to 14 (1.0%) in 2012 and 2016, respectively (P < .001). Additionally, there was a gradual decline in the proportion of meningitis cases caused by pneumococcus, from 77.3% (17/22) in 2011 to 32.4% (11/34) in 2016 (odds ratio, 7.11 [95% confidence interval, 2.08-24.30]). Haemophilus influenzae meningitis fluctuated over the surveillance period and was the predominant pathogen (16/34 [47.1%]) by 2016.

CONCLUSIONS

The observed decrease in pneumococcal meningitis after PCV introduction may be indicative of changing patterns of PBM etiology in Benin. Maintaining vigilant and effective surveillance is critical for understanding these changes and their wider public health implications.

Pediatric Bacterial Meningitis Surveillance in Nigeria From 2010 to 2016, Prior to and During the Phased Introduction of the 10-Valent Pneumococcal Conjugate Vaccine

Background

Historically, Nigeria has experienced large bacterial meningitis outbreaks with high mortality in children. Streptococcus pneumoniae (pneumococcus), Neisseria meningitidis (meningococcus), and Haemophilus influenzae are major causes of this invasive disease. In collaboration with the World Health Organization, we conducted longitudinal surveillance in sentinel hospitals within Nigeria to establish the burden of pediatric bacterial meningitis (PBM).

Methods

From 2010 to 2016, cerebrospinal fluid was collected from children <5 years of age, admitted to 5 sentinel hospitals in 5 Nigerian states. Microbiological and latex agglutination techniques were performed to detect the presence of pneumococcus, meningococcus, and H. influenzae. Species-specific polymerase chain reaction and serotyping/grouping were conducted to determine specific causative agents of PBM.

Results

A total of 5134 children with suspected meningitis were enrolled at the participating hospitals; of these 153 (2.9%) were confirmed PBM cases. The mortality rate for those infected was 15.0% (23/153). The dominant pathogen was pneumococcus (46.4%: 71/153) followed by meningococcus (34.6%: 53/153) and H. influenzae (19.0%: 29/153). Nearly half the pneumococcal meningitis cases successfully serotyped (46.4%: 13/28) were caused by serotypes that are included in the 10-valent pneumococcal conjugate vaccine. The most prevalent meningococcal and H. influenzae strains were serogroup W and serotype b, respectively.

Conclusions

Vaccine-type bacterial meningitis continues to be common among children <5 years in Nigeria. Challenges with vaccine introduction and coverage may explain some of these finding. Continued surveillance is needed to determine the distribution of serotypes/groups of meningeal pathogens across Nigeria and help inform and sustain vaccination policies in the country.

Hospital-based Surveillance for Pediatric Bacterial Meningitis in the Era of the 13-Valent Pneumococcal Conjugate Vaccine in Ghana

Background

Global surveillance for vaccine preventable invasive bacterial diseases has been set up by the World Health Organization to provide disease burden data to support decisions on introducing pneumococcal conjugate vaccine (PCV). We present data from 2010 to 2016 collected at the 2 sentinel sites in Ghana.

Methods

Data were collected from children <5 years of age presenting at the 2 major teaching hospitals with clinical signs of meningitis. Cerebrospinal fluid specimens were collected and tested first at the sentinel site laboratory with conventional microbiology methods and subsequently with molecular analysis, at the World Health Organization Regional Reference Laboratory housed at the Medical Research Council Unit The Gambia, for identification of Streptococcus pneumoniae, Haemophilus influenzae, and Neisseria meningitidis, the 3 most common bacteria causing meningitis.

Results

There were 4008 suspected cases of meningitis during the surveillance period, of which 31 (0.8%) were laboratory confirmed. Suspected meningitis cases decreased from 923 in 2010 to 219 in 2016. Of 3817 patients with available outcome data, 226 (5.9%) died. S. pneumoniae was the most common bacterial pathogen, accounting for 68.5% of confirmed cases (50 of 73). H. influenzae and N. meningitidis accounted for 6.8% (5 of 73) and 21.9% (16 of 73), respectively. The proportion of pneumococcal vaccine serotypes causing meningitis decreased from 81.3% (13 of 16) before the introduction of 13-valent PCV (2010–2012) to 40.0% (8 of 20) after its introduction (2013–2016).

Conclusions

Cases of suspected meningitis decreased among children <5 years of age between 2010 and 2016, with declines in the proportion of vaccine-type pneumococcal meningitis after the introduction of 13-valent PCV in Ghana.

Examining the relationship between household air pollution and infant microbial nasal carriage in a Ghanaian cohort

BACKGROUND

Pneumonia, a leading cause of childhood mortality, is associated with household air pollution (HAP) exposure. Mechanisms between HAP and pneumonia are poorly understood, but studies suggest that HAP may increase the likelihood of bacterial, instead of viral, pneumonia. We assessed the relationship between HAP and infant microbial nasal carriage among 260 infants participating in the Ghana Randomized Air Pollution and Health Study (GRAPHS).

METHODS

Data are from GRAPHS, a cluster-randomized controlled trial of cookstove interventions (improved biomass or LPG) versus the 3-stone (baseline) cookstove. Infants were surveyed for pneumonia during the first year of life and had routine personal exposure assessments. Nasopharyngeal swabs collected from pneumonia cases (n = 130) and healthy controls (n = 130) were analyzed for presence of 22 common respiratory microbes by MassTag polymerase chain reaction. Data analyses included intention-to-treat (ITT) comparisons of microbial species presence by study arm, and exposure-response relationships.

RESULTS

In ITT analyses, 3-stone arm participants had a higher mean number of microbial species than the LPG (LPG: 2.71, 3-stone: 3.34, p < 0.0001, n = 260). This difference was driven by increased bacterial (p < 0.0001) rather than viral species presence (non-significant). Results were pronounced in pneumonia cases and attenuated in healthy controls. Higher prevalence bacterial species were Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis. Exposure-response relationships did not yield significant associations between measured CO and nasal microbial carriage.

CONCLUSIONS

Our intention-to-treat findings are consistent with a link between HAP and bacterial nasal carriage. No relationships were found for viral carriage. Given the null results in exposure-response analysis, it is likely that a pollutant besides CO is driving these differences.

Blood‒Brain Barrier Pathology and CNS Outcomes in Streptococcus pneumoniae Meningitis

Streptococcus pneumoniae is a major meningitis-causing pathogen globally, bringing about significant morbidity and mortality, as well as long-term neurological sequelae in almost half of the survivors. Subsequent to nasopharyngeal colonisation and systemic invasion, translocation across the blood‒brain barrier (BBB) by S. pneumoniae is a crucial early step in the pathogenesis of meningitis. The BBB, which normally protects the central nervous system (CNS) from deleterious molecules within the circulation, becomes dysfunctional in S. pneumoniae invasion due to the effects of pneumococcal toxins and a heightened host inflammatory environment of cytokines, chemokines and reactive oxygen species intracranially. The bacteria‒host interplay within the CNS likely determines not only the degree of BBB pathological changes, but also host survival and the extent of neurological damage. This review explores the relationship between S. pneumoniae bacteria and the host inflammatory response, with an emphasis on the BBB and its roles in CNS protection, as well as both the acute and long-term pathogenesis of meningitis.

Economic burden of pneumococcal infections in children under 5 years of age

The present study aimed to determine the cost of childhood pneumococcal infections under 5 years of age and to provide further data for future health economy studies. Electronic medical records of children diagnosed with meningitis caused by S. pneumoniae and all-cause pneumonia, and acute otitis media (AOM) between January 2013-April 2014 were retrospectively evaluated. Direct costs for the treatments of hospitalized patients (pneumonia and pneumococcal meningitis) including costs of healthcare services consisted of costs of hospital bed, examination, laboratory analyses, scanning methods, consultation, vascular access procedures, and infusion and intravenous treatments. Direct costs for patients (AOM) treated in outpatient setting included constant price paid for the examination and cost of prescribed antibiotics. Indirect costs included cost of work loss of parents and their transportation expenses. Data of 130 children with pneumococcal meningitis (n = 10), pneumonia (n = 53), and AOM (n = 67) were analyzed. The total median cost was €4,060.38 (direct cost: €3,346.38 and indirect cost: €829.18) for meningitis, €835.91 (direct cost: €480.66 and indirect cost: €330.09) for pneumonia, and €117.32 (direct cost: €17.59 and indirect cost: €99.73) for AOM. The medication cost (p = 0.047), indirect cost (p = 0.032), and total cost (p = 0.011) were significantly higher in pneumonia patients aged ≥36 months than those aged <36 months; however, direct cost of AOM were significantly higher in the patients aged <36 months (p = 0.049). Results of the present study revealed that the treatment cost was significantly enhanced for hospitalization and for advanced disease. Thus, preventive actions, mainly vaccination, should be conducted regularly.

Maternal pneumococcal nasopharyngeal carriage and risk factors for neonatal carriage after the introduction of pneumococcal conjugate vaccines in The Gambia

OBJECTIVES

Pneumococcal nasopharyngeal carriage occurs early in life. However, the role of vertical transmission is not well understood. The aims of this study were to describe carriage among mothers and their newborns, and to assess for risk factors for neonatal carriage.

METHODS

In a nested retrospective cohort study, we analysed data from the control arm of a randomized controlled trial conducted in The Gambia 2 to 3 years after introduction of pneumococcal conjugate vaccine (PCV) 13. Nasopharyngeal swabs were collected from 374 women and their newborns on the day of delivery, then 3, 6, 14 and 28 days later. Pneumococci were isolated and serotyped using conventional microbiologic methods.

RESULTS

Carriage increased from 0.3% (1/373) at birth to 37.2% (139/374) at day 28 (p <0.001) among neonates and from 17.1% (64/374) to 24.3% (91/374) (p 0.015) among women. In both groups, PCV13 vaccine-type (VT) serotypes accounted for approximately one-third of the pneumococcal isolates, with serotype 19A being the most common VT. Maternal carriage (adjusted odds ratio (OR) = 2.82; 95% confidence interval (CI), 1.77-4.80), living with other children in the household (adjusted OR = 4.06; 95% CI, 1.90-8.86) and dry season (OR = 1.98; 95% CI, 1.15-3.43) were risk factors for neonatal carriage. Over half (62.6%) of the neonatal carriage was attributable to living with other children in the same household.

CONCLUSIONS

Three years after the introduction of PCV in The Gambia, newborns are still rapidly colonized with pneumococcus, including PCV13 VT. Current strategies for pneumococcal control in Africa do not protect this age group beyond the herd effect.

Cost-effectiveness and Health Benefits of Pediatric 23-valent Pneumococcal Polysaccharide Vaccine, 7-valent Pneumococcal Conjugate Vaccine and Forecasting 13-valent Pneumococcal Conjugate Vaccine in China

BACKGROUND

Each year in China, approximately 700,000 children under 5 years old are diagnosed with pneumonia, and 30,000 die of the disease. Although 7-valent pneumococcal conjugate vaccine (PCV-7) and 23-valent pneumococcal polysaccharide vaccine (PPV-23) are available in China, the costs are borne by the consumer, resulting in low coverage for PCV-7. We aimed to conduct a simulation study to assess the cost-effectiveness and health benefits of PCV-7, 13-valent pneumococcal conjugate vaccine (PCV-13) and PPV-23 to prevent childhood pneumonia and other vaccine-preventive diseases in China.

METHODS

An economic evaluation was performed using a Markov simulation model. Parameters including demographic, epidemiological data, costs and efficacy of vaccines were obtained from previous studies. A hypothetical cohort of 100,000 newborns (focusing on pneumococcal diseases ≤7 years old) was followed up until death or 100 years of age. The model incorporated the impact of vaccination on reduction of incidence of pneumococcal diseases and mortality of children ≤7 years. Outcomes are presented in terms of disease cases averted, quality-adjusted life years (QALYs) and incremental cost-effectiveness ratio.

RESULTS

Under baseline assumptions, PPV-23 is currently the only cost-effective option, whereas PCV-13 showed the greatest impact on pneumococcal disease burden, reducing invasive pneumococcal diseases by 31.3%, pneumonia by 15.3% and gaining 73.8 QALYs (10,000 individuals at discount rate of 3%). Incremental cost-effectiveness ratios of PCV-13 and PCV-7 are US$29,460/QALY and US$104,094/QALY, respectively, showing no cost-effectiveness based on the World Health Organization recommended willingness-to-pay threshold. On the other hand, the incremental cost-effectiveness ratios of PCVs were most sensitive to vaccination costs; if it reduces 4.7% and 32.2% for PCV-7 and PCV-13, respectively, the vaccination will be cost-effective.

CONCLUSIONS

To scale up current vaccination strategies and achieve potential health benefits, the replacement of PCV-7 with PCV-13 should be considered. As well, PCV's costs need to be reduced by increasing public subsidies and providing financial support to poor families.

Simulating Immune Interference on the Effect of a Bivalent Glycoconjugate Vaccine against Haemophilus influenzae Serotypes "a" and "b"

Objective. We sought to evaluate the immune responses to a bivalent Haemophilus influenzae glycoconjugate vaccine against serotypes “a” (Hia) and “b” (Hib) in the presence of the preexisting immunity to Hib. Methods. We developed a stochastic simulation model of humoral immune response to investigate the antigenic challenge of a bivalent combined glycoconjugate vaccine and a bivalent unimolecular glycoconjugate vaccine. We compared simulation outcomes in the absence of any preexisting immunity with an already primed immune response having specific memory B cells and/or anti-Hib antibodies. Results. The simulation results show that the preexisting immune responses to Hib or carrier protein (CP) may significantly impede the production of anti-Hia antibodies by a unimolecular vaccine. In contrast, the production of anti-Hia antibodies using a combined vaccine is inhibited only in the presence of CP immune responses. Conclusions. Preexisting immunity to Hib and CP may play a critical role in the development of immune responses against Hia or Hib using bivalent combined and unimolecular vaccine formulations. Our results suggest that a bivalent combined glycoconjugate vaccine with a carrier protein not previously used in Hib conjugate vaccines may be an effective formulation for generating immune responses to protect against both Hib and Hia infections.

Hearing impairment after childhood bacterial meningitis dependent on etiology in Luanda, Angola

OBJECTIVE

Childhood bacterial meningitis (BM) damages hearing, but the potential of different agents to cause impairment in developing countries is poorly understood. We compared the extent of hearing impairment in BM caused by Haemophilus influenzae type b (Hib), Streptococcus pneumoniae or Neisseria meningitidis among children aged 2 months to 13 years in Luanda, Angola.

METHODS

Hearing of 685 ears of 351 (78%) survivors among 723 enrolled patients was tested by brainstem-evoked response audiometry on day 7 of hospitalization. The causative agent was sought by cerebrospinal fluid culture, PCR or the latex-agglutination test.

RESULTS

Altogether, 45 (12%) of the survivors were deaf (threshold >80 dB), and 20 (6%) had a threshold of 80 dB. The incidence of any kind of hearing loss, with ≥60 dB, was 34% with Hib, 30% with S. pneumoniae, 19% with N. meningitidis and 33% with other bacteria. Examining all ears combined and using the ≥60 dB threshold, the agents showed dissimilar harm (P=0.005), Hib being the most frequent and N. meningitidis the most infrequent cause. Compared to other agents, S. pneumoniae more often caused deafness (P=0.025) and hearing impairment at ≥60 dB (P=0.017) in infants, whereas this level of hearing loss in older survivors was most commonly caused by Hib (P=0.031).

CONCLUSIONS

BM among children in Angola is often followed by hearing impairment, but the risk depends on the agent. S. pneumoniae is a major problem among infants, whereas Hib is mainly a risk beyond 12 months. N. meningitidis impairs hearing less frequently.

Comparative proteomics of cerebrospinal fluid reveals a predictive model for differential diagnosis of pneumococcal, meningococcal, and enteroviral meningitis, and novel putative therapeutic targets

BACKGROUND

Meningitis is the inflammation of the meninges in response to infection or chemical agents. While aseptic meningitis, most frequently caused by enteroviruses, is usually benign with a self-limiting course, bacterial meningitis remains associated with high morbidity and mortality rates, despite advances in antimicrobial therapy and intensive care. Fast and accurate differential diagnosis is crucial for assertive choice of the appropriate therapeutic approach for each form of meningitis.

METHODS

We used 2D-PAGE and mass spectrometry to identify the cerebrospinal fluid proteome specifically related to the host response to pneumococcal, meningococcal, and enteroviral meningitis. The disease-specific proteome signatures were inspected by pathway analysis.

RESULTS

Unique cerebrospinal fluid proteome signatures were found to the three aetiological forms of meningitis investigated, and a qualitative predictive model with four protein markers was developed for the differential diagnosis of these diseases. Nevertheless, pathway analysis of the disease-specific proteomes unveiled that Kallikrein-kinin system may play a crucial role in the pathophysiological mechanisms leading to brain damage in bacterial meningitis. Proteins taking part in this cellular process are proposed as putative targets to novel adjunctive therapies.

CONCLUSIONS

Comparative proteomics of cerebrospinal fluid disclosed candidate biomarkers, which were combined in a qualitative and sequential predictive model with potential to improve the differential diagnosis of pneumococcal, meningococcal and enteroviral meningitis. Moreover, we present the first evidence of the possible implication of Kallikrein-kinin system in the pathophysiology of bacterial meningitis.

Evaluation of duration of antibiotic therapy in neonatal bacterial meningitis: a randomized controlled trial

OBJECTIVES

To compare the effect of 10 days versus 14 days of antibiotic therapy in neonatal meningitis on treatment failure rate.

METHODS

The study was a randomized controlled trial conducted at a referral neonatal unit. The participants were 70 neonates with meningitis randomized to receive 10 days (study group) or 14 days (control group) of antibiotics. The primary outcome measure studied was treatment failure in each group within 28 days of enrolment.

RESULTS

None of the neonates among either of the groups had occurrence of meningitis during follow-up. Occurrence of sepsis was observed after discharge in three neonates in the control group and none in the study group. Brainstem-evoked response audiometry was abnormal in one neonate in the study group. Adverse effects of drugs and neurological deficits were not observed in the study population.

CONCLUSIONS

Short course of antibiotic therapy (10 days) is effective, with potential benefits of shorter hospital stay.

Choosing between 7-, 10- and 13-valent pneumococcal conjugate vaccines in childhood: a review of economic evaluations (2006-2014)

BACKGROUND

Seven-valent pneumococcal conjugate vaccines (PCV7) have been used in children for more than a decade. Given the observed increase in disease caused by pneumococcal serotypes not covered by PCV7, an increasing number of countries are switching from 7-valent to 10- and 13-valent PCVs ("PCV10" and "PCV13"). Economic evaluations are important tools to inform decisions and price negotiations to make such a switch.

OBJECTIVE

This review aims to provide a critical assessment of economic evaluations involving PCV10 or PCV13, published since 2006.

METHODS

We searched Scopus, ISI Web of Science (SCI and SSCI) and Pubmed to retrieve, select and review relevant studies, which were archived between 1st January 2006 and 31st January 2014. The review protocol involved standard extraction of assumptions, methods, results and sponsorships from the original studies.

RESULTS

Sixty-three economic evaluations on PCVs published since January 2006 were identified. About half of these evaluated PCV10 and/or PCV13, the subject of this review. At current prices, both PCV13 and PCV10 were likely judged preferable to PCV7. However, the combined uncertainty related to price differences, burden of disease, vaccine effectiveness, herd and serotype replacement effects determine the preference base for either PCV10 or PCV13. The pivotal assumptions and results of these analyses also depended on which manufacturer sponsored the study.

CONCLUSION

A more thorough exploration of uncertainty should be made in future analyses on this subject, as we lack understanding to adequately model herd and serotype replacement effects to reliably predict the population impact of PCVs. The introduction of further improved PCVs in an environment of evolving antibiotic resistance and under the continuing influence of previous PCVs implies that the complexity and data requirements for relevant analyses will further increase. Decision makers using these analyses should not just rely on an analysis from a single manufacturer.

Valuing vaccination

Vaccination has led to remarkable health gains over the last century. However, large coverage gaps remain, which will require significant financial resources and political will to address. In recent years, a compelling line of inquiry has established the economic benefits of health, at both the individual and aggregate levels. Most existing economic evaluations of particular health interventions fail to account for this new research, leading to potentially sizable undervaluation of those interventions. In line with this new research, we set forth a framework for conceptualizing the full benefits of vaccination, including avoided medical care costs, outcome-related productivity gains, behavior-related productivity gains, community health externalities, community economic externalities, and the value of risk reduction and pure health gains. We also review literature highlighting the magnitude of these sources of benefit for different vaccinations. Finally, we outline the steps that need to be taken to implement a broad-approach economic evaluation and discuss the implications of this work for research, policy, and resource allocation for vaccine development and delivery.

Newborn screening by tandem mass spectrometry for glutaric aciduria type 1: a cost-effectiveness analysis

BACKGROUND

Glutaric aciduria type I (GA-I) is a rare metabolic disorder caused by inherited deficiency of glutaryl-CoA dehydrogenase. Despite high prognostic relevance of early diagnosis and start of metabolic treatment as well as an additional cost saving potential later in life, only a limited number of countries recommend newborn screening for GA-I. So far only limited data is available enabling health care decision makers to evaluate whether investing into GA-I screening represents value for money. The aim of our study was therefore to assess the cost-effectiveness of newborn screening for GA-I by tandem mass spectrometry (MS/MS) compared to a scenario where GA-I is not included in the MS/MS screening panel.

METHODS

We assessed the cost-effectiveness of newborn screening for GA-I against the alternative of not including GA-I in MS/MS screening. A Markov model was developed simulating the clinical course of screened and unscreened newborns within different time horizons of 20 and 70 years. Monte Carlo simulation based probabilistic sensitivity analysis was used to determine the probability of GA-I screening representing a cost-effective therapeutic strategy.

RESULTS

Within a 20 year time horizon, GA-I screening averts approximately 3.7 DALYs (95% CI 2.9 - 4.5) and about one life year is gained (95% CI 0.7 - 1.4) per 100,000 neonates screened initially . Moreover, the screening programme saves a total of around 30,682 Euro (95% CI 14,343 to 49,176 Euro) per 100,000 screened neonates over a 20 year time horizon.

CONCLUSION

Within the limitations of the present study, extending pre-existing MS/MS newborn screening programmes by GA-I represents a highly cost-effective diagnostic strategy when assessed under conditions comparable to the German health care system.

Clinical Burden of Invasive Pneumococcal Disease in Selected Developing Countries

OBJECTIVE

To measure the clinical burden of invasive pneumococcal disease (IPD) in selected developing countries.

METHODS

This is an extensive literature review of published articles on IPD in selected developing countries from East Asia, South Asia, Middle East, sub-Saharan Africa, and Latin America. We reviewed all the articles retrieved from the knowledge bases that were published between the years 2000 and 2010.

RESULTS

After applying the inclusion, exclusion, and quality criteria, the comprehensive review of the literature yielded 10 articles with data for pneumococcal meningitis, septicemia/bacteremia, and pneumonia. These selected articles were from 10 developing countries from five different regions. Out of the 10 selected articles, 8 have a detailed discussion on IPD, one of them has s detailed discussion on bacteremia and meningitis, and another one has discussed pneumococcal bacteremia. Out of these 10 articles, only 5 articles discussed the case-fatality ratio (CFR). In our article review, the incidence of IPD ranged from less than 5/100,000 to 416/100,000 population and the CFR ranged from 12.2% to 80% in the developing countries.

CONCLUSIONS

The review demonstrated that the clinical burden of IPD was high in the developing countries. The incidence of IPD and CFR varies from region to region and from country to country. The IPD burden was highest in sub-Saharan African countries followed by South Asian countries. The CFR was low in high-income countries than in low-income countries.

Haemophilus influenzae and Streptococcus pneumoniae: living together in a biofilm

Streptococcus pneumoniae and Haemophilus influenzae are both commensals of the human nasopharynx with an ability to migrate to other niches within the human body to cause various diseases of the upper respiratory tract such as pneumonia, otitis media and bronchitis. They have long been detected together in a multispecies biofilm in infected tissue. However, an understanding of their interplay is a recent field of study, and while over recent years, there has been research that has identified many specific elements important in these biofilms, to date, it remains questionable whether the relationship between H. influenzae and S. pneumoniae is competitive or cooperative. Additionally, the factors that govern the nature of the interspecies interaction are still undefined. This review aims to collate the information that has emerged on the cocolonization and co-infection by S. pneumoniae and nontypeable H. influenzae (NTHi) and their formation of a multispecies biofilm.

Follow-up of cases of Haemophilus influenzae type b meningitis to determine its long-term sequelae

OBJECTIVE

To measure physical and neurologic impact of Haemophilus influenzae type b (Hib) meningitis on surviving children through short- and long-term follow-up.

STUDY DESIGN

Cases of Hib meningitis, diagnosed at a tertiary level pediatric hospital, were subjected to short- and long-term follow-up and compared with age, sex, and area of residence matched healthy controls. Follow-up assessments included thorough physical and neurodevelopmental assessments using a standardized protocol by a multidisciplinary team.

RESULTS

Assessments of short-term follow-up cohort (n = 64) revealed hearing, vision, mental, and psychomotor deficits in 7.8%, 3%, 20%, and 25% of the cases, respectively. Deficits were 10%, 1.4%, 21%, and 25% in long-term follow-up cohort (n = 71), in that order. Mental and psychomotor deficits were found in 2% of the controls, none of whom had vision or hearing deficits.

CONCLUSIONS

In addition to risk of death, Hib meningitis in children causes severe disabilities in survivors. These data facilitated a comprehensive understanding of the burden of Hib meningitis, specifically in developing countries where disabled children remain incapacitated because of lack of resources and facilities. The evidence generated from this study is expected to provide a compelling argument in favor of introduction and continuation of Hib conjugate vaccine in the national immunization program for children.

Significant sequelae after bacterial meningitis in Niger: a cohort study

BACKGROUND

Beside high mortality, acute bacterial meningitis may lead to a high frequency of neuropsychological sequelae. The Sahelian countries belonging to the meningitis belt experience approximately 50% of the meningitis cases occurring in the world. Studies in Africa have shown that N. meningitidis could cause hearing loss in up to 30% of the cases, exceeding sometimes measles. The situation is similar in Niger which experiences yearly meningitis epidemics and where rehabilitation wards are rare and hearing aids remain unaffordable. The aim of this study was to estimate the frequency of neuropsychological sequelae after acute bacterial meningitis in four of the eight regions of Niger.

METHODS

Subjects exposed to acute bacterial meningitis were enrolled into a cohort with non exposed subjects matched on age and gender. Consenting subjects were interviewed during inclusion and at a control visit two months later. If clinical symptoms or psychological troubles persisted at both visits among the exposed subjects with a frequency significantly greater than that observed among the non exposed subjects, a sequelae was retained. The comparison of the frequency of sequelae between non exposed and exposed subjects to bacterial meningitis was also calculated using the Fisher exact test.

RESULTS

Three persisting functional symptoms were registered: headaches, asthenia, and vertigo among 31.3, 36.9, and 22.4% respectively of the exposed subjects. A significant motor impairment was retrieved among 12.3% of the exposed versus 1.6% of the non exposed subjects. Hearing loss significantly disabled 31.3% of the exposed subjects and 10.4% exhibited a serious deafness.

CONCLUSIONS

This study carried out in Niger confirms two serious neurological sequelae occurring at high frequencies after bacterial meningitis: severe and profound hearing loss and motor impairment. Cochlear implantation and hearing aids are too expensive for populations living in developing countries. Neurological sequelae occurring after meningitis should sensitize African public health authorities on the development of rehabilitation centers. All these challenges can be met through existing strategies and guidelines.

Pneumococcal antibody concentrations and carriage of pneumococci more than 3 years after infant immunization with a pneumococcal conjugate vaccine

BACKGROUND

A 9-valent pneumococcal conjugate vaccine (PCV-9), given in a 3-dose schedule, protected Gambian children against pneumococcal disease and reduced nasopharyngeal carriage of pneumococci of vaccine serotypes. We have studied the effect of a booster or delayed primary dose of 7-valent conjugate vaccine (PCV-7) on antibody and nasopharyngeal carriage of pneumococci 3-4 years after primary vaccination.

METHODOLOGY/PRINCIPAL FINDINGS

We recruited a subsample of children who had received 3 doses of either PCV-9 or placebo (controls) into this follow-up study. Pre- and post- PCV-7 pneumococcal antibody concentrations to the 9 serotypes in PCV-9 and nasopharyngeal carriage of pneumococci were determined before and at intervals up to 18 months post-PCV-7. We enrolled 282 children at a median age of 45 months (range, 38-52 months); 138 had received 3 doses of PCV-9 in infancy and 144 were controls. Before receiving PCV-7, a high proportion of children had antibody concentrations >0.35 µg/mL to most of the serotypes in PCV-9 (average of 75% in the PCV-9 and 66% in the control group respectively). The geometric mean antibody concentrations in the vaccinated group were significantly higher compared to controls for serotypes 6B, 14, and 23F. Antibody concentrations were significantly increased to serotypes in the PCV-7 vaccine both 6-8 weeks and 16-18 months after PCV-7. Antibodies to serotypes 6B, 9V and 23F were higher in the PCV-9 group than in the control group 6-8 weeks after PCV-7, but only the 6B difference was sustained at 16-18 months. There was no significant difference in nasopharyngeal carriage between the two groups.

CONCLUSIONS/SIGNIFICANCE

Pneumococcal antibody concentrations in Gambian children were high 34-48 months after a 3-dose primary infant vaccination series of PCV-9 for serotypes other than serotypes 1 and 18C, and were significantly higher than in control children for 3 of the 9 serotypes. Antibody concentrations increased after PCV-7 and remained raised for at least 18 months.

Burden of pneumonia and meningitis caused by Streptococcus pneumoniae in China among children under 5 years of age: a systematic literature review

BACKGROUND AND METHODS

To understand the burden and epidemiology of Streptococcus pneumoniae disease among children between 1 and 59 months of age in China, we conducted a review of literature published between 1980 and 2008 applying standardized algorithms. Because of the absence of population-based surveillance for pneumococcal disease (PD), we identified all-cause pneumonia, bacteremia and meningitis burden, syndromes most commonly associated with S. pneumoniae, and applied the proportion of disease attributable to S. pneumoniae from studies that determined the etiology of these three syndromes to calculate PD burden. Because of the microbiologic difficulties in identifying S. pneumoniae-attributable pneumonia which likely underestimates the pneumonia burden, we also used the proportion obtained from vaccine efficacy trials.

RESULTS

Between 1980 and 2008, there were 12,815 cases/100,000/year of all-cause pneumonia among children between 1 month and 59 months, with 526 deaths/100,000 annually. There were 14 meningitis cases/100,000/year. We estimate that as of 2000, there were 260,768 (113,000 to 582,382) and 902 (114-4,463) cases of pneumococcal pneumonia and meningitis, respectively with 10,703 (4,638-23,904) and 75 (9-370) pneumococcal pneumonia and meningitis deaths, respectively. Pneumococcal pneumonia cases and deaths were more than two-fold higher, 695,382 (173,845-1,216,918) and 28,542 (7,136-49,949), respectively, when parameters from efficacy trials were used. Serotypes 19F, 19A and 14 were the most common serotypes obtained from pneumonia/meningitis patients. Currently available vaccines are expected to cover 79.5% to 88.4% of the prevalent serotypes. With high antibiotic resistance, introducing pneumococcal vaccines to the routine immunization program should be considered in China. Population-based studies are warranted.

Long-term mortality in children diagnosed with Haemophilus influenzae meningitis: a Danish nationwide cohort study

BACKGROUND

The long-term mortality in children diagnosed with Haemophilus influenzae meningitis is poorly documented.

METHODS

We performed a nationwide, population-based cohort study including all Danish children diagnosed at the age between 0 and <5 years with H. influenzae meningitis from 1977 through 1996 and who were alive 1 year after diagnosis. Data were retrieved from medical databases in Denmark. For each H. influenzae meningitis patient, 6 age- and gender-matched population controls were indentified. We constructed Kaplan-Meier survival curves and used Cox regression analysis to estimate mortality rate ratios (MRR) and analyze causes of death. The risk of inpatient admission and of requiring hospital outpatient services during follow-up was calculated.

RESULTS

We identified 1242 H. influenzae meningitis patients and 7452 population controls, with a median follow-up time of 21.3 years. The MRR for patients with H. influenzae meningitis was 1.08 (95% confidence interval, 0.57-2.05), adjusted MRR was 0.97 (95% confidence interval, 0.50-1.89). No increased mortality due to infections, respiratory diseases, or cancer was observed. The overall risk of inpatient admission and of requiring hospital outpatient services for the H. influenzae meningitis patients was increased the first 15 years of follow-up, mainly due to the nervous system diseases and ear diseases, thereafter the risk decreased to that of the population controls.

CONCLUSIONS

In a developed country, children younger than 5 years surviving the acute phase of H. influenzae meningitis have no increased long-term mortality and only moderately increased morbidity.

The cost effectiveness of pneumococcal conjugate vaccine in the routine infant immunisation programme of The Gambia

Objectives

To evaluate the cost effectiveness of the use of nine-valent pneumococcal polysaccharide conjugate vaccine in a routine infant immunisation programme based on the Pneumococcal Vaccine Trial (PVT) study in The Gambia.

Methods

This was a clinical trial-based cost-effectiveness study conducted as part of the PVT study. The PVT was an intention-to-treat double-blind placebo-controlled trial of a nine-valent pneumococcal polysaccharide conjugate vaccine. The trial was conducted in the eastern parts of The Gambia, West Africa and recruited 17 437 children aged 40–364 days. A deterministic static cohort model was developed to evaluate direct benefits and costs of pneumococcal conjugate vaccine in The Gambia's routine immunisation programme. The incremental cost-effectiveness ratio (iCER) is defined as vaccinating infants against pneumococcal disease compared with no vaccination from a public provider's perspective using The Gambia's 2005 projected under-one-year population.

Key findings

The results show the use of the vaccine in The Gambia's routine infant vaccination programme to be cost effective using an assumed price of US$5.00 per vial in single-dose vials. Compared with offering no vaccination, the incremental cost per DALYs averted would be 30 DALYs from the public provider perspective. At least 1569 and 340 invasive childhood pneumococcal illnesses and deaths respectively among the cohort would be prevented. In the absence of the vaccine 16 871 DALYs would be lost while with the use of the vaccine 7804 DALYs would be lost. Given the average treatment cost of pneumococcal illnesses to be US$191 (95% confidence interval 180 to 203) the introduction of the vaccine programme would lead to an additional cost of US$274 279 (about US$8.43/child).

Conclusions

The availability of a cost-effective vaccine that can prevent thousands of pneumococcal illnesses and related deaths is a major development towards improving the disease burden in sub-Saharan African countries. This study supports the introduction of nine-valent pneumococcal vaccine into the infant immunisation programme of The Gambia as it is cost effective and will avert many preventable deaths and illnesses. Despite differences in distribution of serotypes between countries, the static model used in the analysis makes the results applicable to other developing countries, particularly those in sub-Saharan Africa.

5 versus 10 days of treatment with ceftriaxone for bacterial meningitis in children: a double-blind randomised equivalence study

BACKGROUND

Bacterial meningitis is an important cause of morbidity and mortality in developing countries, but the duration of treatment is not well established. We aimed to compare the efficacy of 5 and 10 days of parenteral ceftriaxone for the treatment of bacterial meningitis in children.

METHODS

We did a multicountry, double-blind, placebo-controlled, randomised equivalence study of 5 versus 10 days of treatment with ceftriaxone in children aged 2 months to 12 years with purulent meningitis caused by Streptococcus pneumoniae, Haemophilus influenzae type B, or Neisseria meningitidis. Our study was done in ten paediatric referral hospitals in Bangladesh, Egypt, Malawi, Pakistan, and Vietnam. We randomly assigned children who were stable after 5 days of treatment, through site-balanced computer-generated allocation lists, to receive a further 5 days of ceftriaxone or placebo. Patients, their guardians, and staff were masked to study-group allocation. Our primary outcomes were bacteriological failure or relapse. Our analysis was per protocol. This study is registered with the International Standard Randomised Controlled Trial Number Register, number ISRCTN38717320.

FINDINGS

We included 1004 of 1027 children randomly assigned to study groups in our analyses; 496 received treatment with ceftriaxone for 5 days, and 508 for 10 days. In the 5-day treatment group, two children (one infected with HIV) had a relapse; there were no relapses in the 10-day treatment group and there were no bacteriological failures in either study group. Side-effects of antibiotic treatment were minor and similar in both groups.

INTERPRETATION

In children beyond the neonatal age-group with purulent meningitis caused by S pneumoniae, H influenzae type b, or N meningitidis who are stable by day 5 of ceftriaxone treatment, the antibiotic can be safely discontinued.

FUNDING

United States Agency for International Development.

Economic evaluation of pneumococcal conjugate vaccination in The Gambia

BACKGROUND

Gambia is the second GAVI support-eligible country to introduce the 7-valent pneumococcal conjugate vaccine (PCV7), but a country-specific cost-effectiveness analysis of the vaccine is not available. Our objective was to assess the potential impact of PCVs of different valences in The Gambia.

METHODS

We synthesized the best available epidemiological and cost data using a state-transition model to simulate the natural histories of various pneumococcal diseases. For the base-case, we estimated incremental cost (in 2005 US dollars) per disability-adjusted life year (DALY) averted under routine vaccination using PCV9 compared to no vaccination. We extended the base-case results for PCV9 to estimate the cost-effectiveness of PCV7, PCV10, and PCV13, each compared to no vaccination. To explore parameter uncertainty, we performed both deterministic and probabilistic sensitivity analyses. We also explored the impact of vaccine efficacy waning, herd immunity, and serotype replacement, as a part of the uncertainty analyses, by assuming alternative scenarios and extrapolating empirical results from different settings.

RESULTS

Assuming 90% coverage, a program using a 9-valent PCV (PCV9) would prevent approximately 630 hospitalizations, 40 deaths, and 1000 DALYs, over the first 5 years of life of a birth cohort. Under base-case assumptions ($3.5 per vaccine), compared to no intervention, a PCV9 vaccination program would cost $670 per DALY averted in The Gambia. The corresponding values for PCV7, PCV10, and PCV13 were $910, $670, and $570 per DALY averted, respectively. Sensitivity analyses that explored the implications of the uncertain key parameters showed that model outcomes were most sensitive to vaccine price per dose, discount rate, case-fatality rate of primary endpoint pneumonia, and vaccine efficacy against primary endpoint pneumonia.

CONCLUSIONS

Based on the information available now, infant PCV vaccination would be expected to reduce pneumococcal diseases caused by S. pneumoniae in The Gambia. Assuming a cost-effectiveness threshold of three times GDP per capita, all PCVs examined would be cost-effective at the tentative Advance Market Commitment (AMC) price of $3.5 per dose. Because the cost-effectiveness of a PCV program could be affected by potential serotype replacement or herd immunity effects that may not be known until after a large scale introduction, type-specific surveillance and iterative evaluation will be critical.

Global and regional risk of disabling sequelae from bacterial meningitis: a systematic review and meta-analysis

Few data sources are available to assess the global and regional risk of sequelae from bacterial meningitis. We aimed to estimate the risks of major and minor sequelae caused by bacterial meningitis, estimate the distribution of the different types of sequelae, and compare risk by region and income. We systematically reviewed published papers from 1980 to 2008. Standard global burden of disease categories (cognitive deficit, bilateral hearing loss, motor deficit, seizures, visual impairment, hydrocephalus) were labelled as major sequelae. Less severe, minor sequelae (behavioural problems, learning difficulties, unilateral hearing loss, hypotonia, diplopia), and multiple impairments were also included. 132 papers were selected for inclusion. The median (IQR) risk of at least one major or minor sequela after hospital discharge was 19.9% (12.3-35.3%). The risk of at least one major sequela was 12.8% (7.2-21.1%) and of at least one minor sequela was 8.6% (4.4-15.3%). The median (IQR) risk of at least one major sequela was 24.7% (16.2-35.3%) in pneumococcal meningitis; 9.5% (7.1-15.3%) in Haemophilus influenzae type b (Hib), and 7.2% (4.3-11.2%) in meningococcal meningitis. The most common major sequela was hearing loss (33.9%), and 19.7% had multiple impairments. In the random-effects meta-analysis, all-cause risk of a major sequela was twice as high in the African (pooled risk estimate 25.1% [95% CI 18.9-32.0%]) and southeast Asian regions (21.6% [95% CI 13.1-31.5%]) as in the European region (9.4% [95% CI 7.0-12.3%]; overall I(2)=89.5%, p<0.0001). Risks of long-term disabling sequelae were highest in low-income countries, where the burden of bacterial meningitis is greatest. Most reported sequelae could have been averted by vaccination with Hib, pneumococcal, and meningococcal vaccines.

New-onset seizures in pediatric emergency

BACKGROUND

Seizures account for 1% of all pediatric emergency department (ED) visits. The aim of this study was to analyze the clinical spectrum and prevalence rates of various etiologies in children with a first attack of acute seizure disorder in the ED.

METHODS

We evaluated 319 children who presented to the ED at the Changhua Children's Hospital with a first attack of seizure disorder from 2005 to 2007. Variables including demographics, clinical presentations, laboratory tests, brain imaging studies, electroencephalography, diagnoses and hospital course were compared between patients with seizures and fever, and patients with seizures without fever. These variables were also compared between patients with simple and complex febrile seizures and among different age groups.

RESULTS

Among these 319 patients, 218 (68%) presented with seizures and fever and 299 (94%) children were younger than 6 years of age. Generalized tonic-clonic seizures were the most common type (71.2%). Febrile seizures (62.1%) were the main etiology of the first seizure (p < 0.001). Seizures caused by severe electrolyte imbalance or hypoglycemia were noted in three patients. Abnormal brain images were noted in 16 (26%) of 61 patients, most (12/16, 75%) of whom had abnormal histories and physical or neurologic examinations.

CONCLUSION

Primary care pediatricians should evaluate children presenting to the ED with a first seizure for age, coexistence of fever, seizure type, associated symptoms and history of head injury. We suggest that electrolytes, blood sugar and emergent brain imaging studies should be arranged based on detailed history-taking and thorough physical examinations, but should not be performed routinely.

Diagnosis of Streptococcus pneumoniae and Haemophilus influenzae type b meningitis by identifying DNA from cerebrospinal fluid-impregnated filter paper strips

BACKGROUND

Bacterial meningitis remains often etiologically unconfirmed, especially in resource-poor settings. We tested the potential of real-time polymerase chain reaction to identify Streptococcus pneumoniae (Pnc) and Haemophilus influenzae type b (Hib) from cerebrospinal fluid impregnated on filter paper strips.

METHODS

Pnc and Hib genome equivalents were blindly quantified by polymerase chain reaction from 129 liquid cerebrospinal fluid (CSF) samples-the standard-and strips stored at room temperature for months. Genome counts were compared by simple regression.

RESULTS

The strips showed a sensitivity and specificity of 92% and 99% for Pnc, and of 70% and 100% for Hib, respectively. The positive and negative predictive values were 94% and 97% for Pnc, and 100% and 89% for Hib, respectively. For Pnc, the positive and negative likelihood ratio was 92 and 0.08, and the overall accuracy 98%, whereas for Hib they were 70 and 0.30, and 91%, respectively. Genome counting showed good correlation between the filter paper and liquid CSF samples, r(2) being 0.87 for Pnc and 0.68 for Hib (P < 0.0001 for both).

CONCLUSION

Although not replacing bacterial culture, filter paper strips offer an easy way to collect and store CSF samples for later bacteriology. They can also be transported in standard envelops by regular mail.

Sequelae due to bacterial meningitis among African children: a systematic literature review

BACKGROUND

African children have some of the highest rates of bacterial meningitis in the world. Bacterial meningitis in Africa is associated with high case fatality and frequent neuropsychological sequelae. The objective of this study is to present a comprehensive review of data on bacterial meningitis sequelae in children from the African continent.

METHODS

We conducted a systematic literature search to identify studies from Africa focusing on children aged between 1 month to 15 years with laboratory-confirmed bacterial meningitis. We extracted data on neuropsychological sequelae (hearing loss, vision loss, cognitive delay, speech/language disorder, behavioural problems, motor delay/impairment, and seizures) and mortality, by pathogen.

RESULTS

A total of 37 articles were included in the final analysis representing 21 African countries and 6,029 children with confirmed meningitis. In these studies, nearly one fifth of bacterial meningitis survivors experienced in-hospital sequelae (median = 18%, interquartile range (IQR) = 13% to 27%). About a quarter of children surviving pneumococcal meningitis and Haemophilus influenzae type b (Hib) meningitis had neuropsychological sequelae by the time of hospital discharge, a risk higher than in meningococcal meningitis cases (median = 7%). The highest in-hospital case fatality ratios observed were for pneumococcal meningitis (median = 35%) and Hib meningitis (median = 25%) compared to meningococcal meningitis (median = 4%). The 10 post-discharge studies of children surviving bacterial meningitis were of varying quality. In these studies, 10% of children followed-up post discharge died (range = 0% to 18%) and a quarter of survivors had neuropsychological sequelae (range = 3% to 47%) during an average follow-up period of 3 to 60 months.

CONCLUSION

Bacterial meningitis in Africa is associated with high mortality and risk of neuropsychological sequelae. Pneumococcal and Hib meningitis kill approximately one third of affected children and cause clinically evident sequelae in a quarter of survivors prior to hospital discharge. The three leading causes of bacterial meningitis are vaccine preventable, and routine use of conjugate vaccines could provide substantial health and economic benefits through the prevention of childhood meningitis cases, deaths and disability.

Seven-valent pneumococcal conjugate vaccines for developing countries

Protein conjugate bacterial vaccines for invasive pneumococcal diseases have revolutionized the epidemiology of invasive bacterial disease in young children in most of the developed world, but only a small proportion of children at greatest risk of dying from this disease are vaccinated in less developed countries. Pneumococcal disease kills more children than any other illness - more than AIDS, malaria and measles combined. While the noble effort of international agencies to promote the use of pneumococcal vaccines is commendable, studies from several developing countries have failed to recognize invasive pneumococcal disease as a major problem. Thus, even at considerably subsidized vaccine pricing, this failure to recognize the pneumococcal disease burden will deter the introduction of vaccine programs in areas where it is most needed. This lack of awareness creates an impassé for the acceptance of a 'solution'. Whether this absence of evidence is real or simply misleading deserves further urgent evaluation. Such an evaluation could propose the use of the vaccine as a 'probe' for defining the problem. In settings where disease burden is likely to be highest, disease surveillance is nonexistent, childhood immunization programs are fractured or nonexistent, and there is no system to ensure delivery, even if the vaccine is offered free of charge. Ongoing challenges with global polio eradication programs suggest that, critical to the success of any immunization program, is investment in setting up credible disease surveillance systems for vaccine preventable diseases to generate local or regional disease burden data. This will promote local ownership of any immunization programs and reveal myths about a 'hidden agenda' by foreign vaccine manufacturers.

Increase in serum osmolality is possible mechanism for the beneficial effects of glycerol in childhood bacterial meningitis

BACKGROUND

Oral glycerol reduces severe neurologic sequelae in childhood bacterial meningitis, but the mechanism awaits elucidation. We conducted a prospective, randomized, double-blind study in which the effects of glycerol and intravenous dexamethasone were compared with placebo recipients in an intensive care setting in India.

METHODS

Thirty-six children at age 2 months to 12 years with meningitis were treated with ceftriaxone and were randomized to receive also either dexamethasone intravenously, or glycerol orally, or both agents, or neither. The illness was monitored with preset criteria. The primary outcome measures were the changes in plasma osmolality and in urine output.

RESULTS

Nine children received glycerol, 8 dexamethasone, 11 both agents, and 8 only placebo. The leading agents identified were Streptococcus pneumoniae, Haemophilus influenzae type b, and Staphylococcus aureus. Only the glycerol recipients increased plasma osmolality by up to 3% from the mean baseline of 294 mOsm/kg in the glycerol and 295 mOsm/kg in the glycerol-dexamethasone group. This change occurred within 6 hours, the critical period of treatment, and lasted <24 hours. Blood pressure was not affected, nor did urine output increase. The dexamethasone-only and placebo-only recipients showed immediate decrease in serum osmolality.

CONCLUSIONS

Because excretion of the cerebrospinal fluid is inversely associated with plasma osmolality, we suggest that the glycerol-induced osmolality increase reduce the volume of cerebrospinal fluid, enhanced water movement back to the plasma by osmosis, increased cerebral blood flow, and thus, improved brain oxygenation.

Vaccine-preventable haemophilus influenza type B disease burden and cost-effectiveness of infant vaccination in Indonesia

BACKGROUND

Most of Asia, including Indonesia, does not use Haemophilus influenzae type b (Hib) conjugate vaccines. We estimated total vaccine-preventable disease burden and the cost-effectiveness of Hib conjugate vaccine in Indonesia.

METHODS

Hib pneumonia and meningitis incidences for children with access to health care were derived from a randomized vaccine probe study on Lombok Island, Indonesia during 1998-2002. Incidences were adjusted for limited access to care. Health system and patient out-of-pocket treatment cost data were collected concurrent with the probe study. For Hib vaccine in monovalent and combined (with DTP-HepB) presentations, we used 2007 UNICEF vaccine prices of US$3.30 and $3.75 per dose.

RESULTS

For the 2007 Indonesian birth cohort, Hib vaccine would prevent meningitis in 1 of every 179 children, pneumonia in 1 of every 18 children, and 4.9% of mortality among those younger than 5 years. The total incremental societal costs of introducing Hib vaccine in monovalent and pentavalent presentations were, respectively, US$11.74 and $8.93 per child vaccinated. Annual discounted treatment costs averted amounted to 20% of pentavalent vaccine costs. For the pentavalent vaccine, the incremental costs per discounted death and disability adjusted life-year averted amounted to US$3102 and $74, respectively, versus $4438 and $102 for monovalent vaccine.

CONCLUSIONS

Routine infant Hib vaccination would prevent a large burden of pediatric illness and death in Indonesia. Even without external funding support, Hib vaccine will be a highly cost-effective intervention in either a monovalent or pentavalent presentation based on commonly used benchmarks.