Effectiveness of Haemophilus influenzae type b Conjugate vaccine introduction into routine childhood immunization in Kenya

Consulting communities on feedback of genetic findings in international health research: sharing sickle cell disease and carrier information in coastal Kenya

BACKGROUND

International health research in malaria-endemic settings may include screening for sickle cell disease, given the relationship between this important genetic condition and resistance to malaria, generating questions about whether and how findings should be disclosed. The literature on disclosing genetic findings in the context of research highlights the role of community consultation in understanding and balancing ethically important issues from participants' perspectives, including social forms of benefit and harm, and the influence of access to care. To inform research practice locally, and contribute to policy more widely, this study aimed to explore the views of local residents in Kilifi County in coastal Kenya on how researchers should manage study-generated information on sickle cell disease and carrier status.

METHODS

Between June 2010 and July 2011, we consulted 62 purposively selected Kilifi residents on how researchers should manage study-generated sickle cell disease findings. Methods drew on a series of deliberative informed small group discussions. Data were analysed thematically, using charts, to describe participants' perceptions of the importance of disclosing findings, including reasoning, difference and underlying values. Themes were derived from the underlying research questions and from issues emerging from discussions. Data interpretation drew on relevant areas of social science and bioethics literature.

RESULTS

Perceived health and social benefits generated strong support for disclosing findings on sickle cell disease, but the balance of social benefits and harms was less clear for sickle cell trait. Many forms of health and social benefits and harms of information-sharing were identified, with important underlying values related to family interests and the importance of openness. The influence of micro and macro level contextual features and prioritization of values led to marked diversity of opinion.

CONCLUSIONS

The approach demonstrates a high ethical importance in many malaria endemic low-to-middle income country settings of disclosing sickle cell disease findings generated during research, alongside provision of effective care and locally-informed counselling. Since these services are central to the benefits of disclosure, health researchers whose studies include screening for sickle cell disease should actively promote the development of health policy and services for this condition in situations of unmet need, including through the prior development of collaborative partnerships with government health managers and providers. Community consultation can importantly enrich ethical debate on research practice where in-depth exploration of informed views and the potential for difference are taken into account.

The effect of Haemophilus influenzae type B and pneumococcal conjugate vaccines on childhood meningitis mortality: a systematic review

Background

Two of the most prevalent causes of severe bacterial meningitis in children, Haemophilus influenzae type B (Hib) and Streptococcus pneumoniae, are preventable by existing vaccines increasingly available in developing countries. Our objective was to estimate the dose-specific effect of Hib and pneumococcal conjugate vaccines (PCV) on childhood meningitis mortality in low-income countries for use in the Lives Saved Tool (LiST).

Methods

We systematically searched and reviewed published vaccine efficacy trials and observational studies reporting the effect of Hib or PCV vaccines on organism-specific meningitis, bacterial meningitis and all-cause meningitis incidence and mortality among children less than five years old in low- and middle-income countries. Data collection and quality assessments were performed using standardized guidelines. For outcomes available across multiple studies (≥2) and approximating meningitis mortality, we pooled estimates reporting dose-specific effects using random effects meta-analytic methods, then combined these with meningitis etiology data to determine the preventable fraction of childhood meningitis mortality for inclusion in LiST.

Results

We identified 18 studies of Hib conjugate vaccines reporting relevant meningitis morbidity and mortality outcomes (2 randomized controlled trials [RCTs], 16 observational studies) but few provided dose-specific effects. A meta-analysis of four case-control studies examined the dose-specific effect of Hib conjugate vaccines on Hib meningitis morbidity (1 dose: RR=0.64, 95% CI 0.38-1.06; 2 doses: RR=0.09, 95% CI 0.03-0.27; 3 doses: RR=0.06, 95% CI 0.02-0.22), consistent with results from single RCTs. Pooled estimates of two RCTs provided evidence for the effect of three doses of PCV on vaccine-serotype meningitis morbidity (RR=0.16, 95% CI 0.02-1.20). We considered these outcomes of severe disease as proxy estimates for meningitis mortality and combined the estimates of protective effects with meningitis etiology data to provide an estimate of the preventable fraction of childhood meningitis mortality with three doses of Hib (38-43%) and pneumococcal conjugate vaccines (28-35%) for use in LiST.

Conclusions

Few RCTs or vaccine effectiveness studies evaluated the dose-specific impact of Hib and PCV vaccines on childhood meningitis mortality, necessitating use of proxy measures to estimate population impact in LiST. Our analysis indicates that approximately three-quarters of meningitis deaths are preventable with existing Hib and PCV vaccines.

Childhood acute non-traumatic coma: aetiology and challenges in management in resource-poor countries of Africa and Asia

OBJECTIVE

This review examines the best available evidence on the aetiology of childhood acute non-traumatic coma in resource-poor countries (RPCs), discusses the challenges associated with management, and explores strategies to address them.

METHODS

Publications in English and French which reported on studies on the aetiology of childhood non-traumatic coma in RPCs are reviewed. Primarily, the MEDLINE database was searched using the keywords coma, unconsciousness, causality, aetiology, child, malaria cerebral, meningitis, encephalitis, Africa, Asia, and developing countries.

RESULTS

14 records were identified for inclusion in the review. Cerebral malaria (CM) was the commonest cause of childhood coma in most of the studies conducted in Africa. Acute bacterial meningitis (ABM) was the second most common known cause of coma in seven of the African studies. Of the studies in Asia, encephalitides were the commonest cause of coma in two studies in India, and ABM was the commonest cause of coma in Pakistan. Streptococcus pneumoniae was the most commonly isolated organism in ABM. Japanese encephalitis, dengue fever and enteroviruses were the viral agents most commonly isolated.

CONCLUSION

Accurate diagnosis of the aetiology of childhood coma in RPCs is complicated by overlap in clinical presentation, limited diagnostic resources, disease endemicity and co-morbidity. For improved outcomes, studies are needed to further elucidate the aetiology of childhood coma in RPCs, explore simple and practical diagnostic tools, and investigate the most appropriate specific and supportive interventions to manage and prevent infectious encephalopathies.

Haemophilus influenzae type b disease among children in rural Mozambique: impact of vaccine introduction

OBJECTIVE

Haemophilus influenzae type b (Hib) conjugate vaccine has dramatically reduced invasive Hib disease worldwide. Yet, data on protection against pneumonia and among children with HIV are limited. We evaluated the impact of Hib conjugate vaccine introduction in 2009 in a rural, high-HIV prevalence area in Mozambique.

STUDY DESIGN

From 2006-2011, we conducted hospital-based surveillance for invasive Hib disease and clinical pneumonia (classified as severe and very severe) among children <5 years of age. Incidences calculated using population denominators were compared between baseline (2006-2008) and post-Hib conjugate vaccine (2010-2011) periods. Surveillance data for radiologically-confirmed pneumonia among children <2 years of age in 2011 were compared with baseline data from 2004-2006.

RESULTS

Among 50 cases of invasive Hib disease, 5 occurred after Hib conjugate vaccine introduction; 1 case-patient was age-eligible for Hib conjugate vaccine (and had received 3 doses). Four post-Hib conjugate vaccine case-patients (including Hib conjugate vaccine failure) had HIV. Among children <1 and <5 years of age, significant reductions occurred in rates of invasive Hib disease (91% and 85%, respectively) and very severe pneumonia (29% and 34%, respectively). Radiologically-confirmed pneumonia incidence fell significantly (33%) in children <2 years of age. Severe pneumonia incidence did not decline.

CONCLUSIONS

We demonstrate important reductions in invasive disease and pneumonia following Hib conjugate vaccine introduction in a high-HIV area. Continued surveillance is needed to monitor long-term Hib conjugate vaccine effects, particularly among children with HIV.

Evaluation of the effectiveness of Haemophilus influenzae type b conjugate vaccine introduction against radiologically-confirmed hospitalized pneumonia in young children in Ukraine

OBJECTIVE

Haemophilus influenzae type b (Hib) conjugate vaccine was included into the national vaccination schedule of Ukraine in 2006. The objective of this study was to demonstrate the effectiveness of Hib conjugate vaccine against radiologically-confirmed hospitalized pneumonia in children.

STUDY DESIGN

Children <2 years old with radiologically confirmed pneumonia admitted to 11 participating hospitals in Kiev and Dnepropetrovsk between April 2007 and June 2009 were included in a case-control evaluation. Four controls were matched to each case by date of birth (within 14 days) and outpatient clinic. We estimated ORs for vaccination and vaccine effectiveness ((1 - OR)*100%) using conditional logistic regression, adjusting for comorbid conditions and contraindications for vaccination.

RESULTS

We enrolled 188 case-children and 735 controls. Median age was 16 months (range 4-24 months). Fifty-one percent of cases and 67% of controls received ≥1 doses of Hib conjugate vaccine; 26% of cases and 37% of controls received ≥3 doses. The effectiveness of ≥1 dose Hib conjugate vaccine was estimated at 45% (95% CI 18%-63%).

CONCLUSIONS

Our study showed that Hib infections are important causes of hospitalized radiologically confirmed pneumonia in young children in Ukraine.

Assessment of health benefits and cost-effectiveness of 10-valent and 13-valent pneumococcal conjugate vaccination in Kenyan children

BACKGROUND

The GAVI Alliance supported 10-valent pneumococcal conjugate vaccine (PCV10) introduction in Kenya. We estimated the cost-effectiveness of introducing either PCV10 or the 13-valent vaccine (PCV13) from a societal perspective and explored the incremental impact of including indirect vaccine effects.

METHODS

The costs and effects of pneumococcal vaccination among infants born in Kenya in 2010 were assessed using a decision analytic model comparing PCV10 or PCV13, in turn, with no vaccination. Direct vaccine effects were estimated as a reduction in the incidence of pneumococcal meningitis, sepsis, bacteraemic pneumonia and non-bacteraemic pneumonia. Pneumococcal disease incidence was extrapolated from a population-based hospital surveillance system in Kilifi and adjustments were made for variable access to care across Kenya. We used vaccine efficacy estimates from a trial in The Gambia and accounted for serotype distribution in Kilifi. We estimated indirect vaccine protection and serotype replacement by extrapolating from the USA. Multivariable sensitivity analysis was conducted using Monte Carlo simulation. We assumed a vaccine price of US$ 3.50 per dose.

FINDINGS

The annual cost of delivering PCV10 was approximately US$14 million. We projected a 42.7% reduction in pneumococcal disease episodes leading to a US$1.97 million reduction in treatment costs and a 6.1% reduction in childhood mortality annually. In the base case analysis, costs per discounted DALY and per death averted by PCV10, amounted to US$ 59 (95% CI 26-103) and US$ 1,958 (95% CI 866-3,425), respectively. PCV13 introduction improved the cost-effectiveness ratios by approximately 20% and inclusion of indirect effects improved cost-effectiveness ratios by 43-56%. The break-even prices for introduction of PCV10 and PCV13 are US$ 0.41 and 0.51, respectively.

CONCLUSIONS

Introducing either PCV10 or PCV13 in Kenya is highly cost-effective from a societal perspective. Indirect effects, if they occur, would significantly improve the cost-effectiveness.

Incidence of convulsive epilepsy in a rural area in Kenya

Purpose

There are only a few studies of incidence of epilepsy in low and middle income countries (LMICs). These are often small and conducted in specific age groups or areas where the prevalence of risk factors is high; therefore, these studies are not representative of the wider populations. We determined the incidence of convulsive epilepsy (CE) in a large rural population in Kenya.

Methods

We conducted two cross‐sectional surveys 5 years apart within a health and demographic surveillance system. Initially we identified residents without epilepsy who were then reexamined in the follow‐up survey to determine incidence. We estimated the overall incidence of CE and incidence by age‐group, sex, and by administrative location. Estimates were adjusted for attrition during case identification and for the sensitivity of the screening method.

Key Findings

In a cohort of 151,408 people, 194 developed CE over the 5 years. The minimum crude incidence rate was 37.6/100,000 persons per year (95% confidence interval (CI) 32.7–43.3) and adjusted for loss to follow‐up, and the sensitivity of the survey methodology was 77.0/100,000 persons per year (95% CI 67.7–87.4). Incidence was highest in children 6–12 years (96.1/100,000 persons per year; 95% CI 78.4–117.9), and was lowest in the 29–49 year age group (37.4/100,000 persons per year; 95% CI 25.7–54.7).

Significance

We estimated a high incidence of convulsive epilepsy in this population. Incidence was highest early and late in life, suggesting that preventive interventions should target exposures that occur in these age groups. Incidence of focal epilepsy was more than twice that of generalized epilepsy, suggesting that etiologies that are amenable to intervention were most important in this population. It is likely that incidence is underestimated because of the early mortality of incident cases.

Prospective multi-centre sentinel surveillance for Haemophilus influenzae type b & other bacterial meningitis in Indian children

BACKGROUND & OBJECTIVES

Haemophilus influenzae type b (Hib) is one of the leading bacterial causes of invasive disease in populations without access to Hib conjugate vaccines (Hib-CV). India has recently decided to introduce Hib-CV into the routine immunization programme in selected States. Longitudinal data quantifying the burden of bacterial meningitis and the proportion of disease caused by various bacteria are needed to track the impact of Hib-CV once introduced. A hospital-based sentinel surveillance network was established at four places in the country and this study reports the results of this ongoing surveillance.

METHODS

Children aged 1 to 23 months with suspected bacterial meningitis were enrolled in Chennai, Lucknow, New Delhi, and Vellore between July 2008 and June 2010. All cerebrospinal fluid (CSF) samples were tested using cytological, biochemical, and culture methods. Samples with abnormal CSF (≥10 WBC per μl) were tested by latex agglutination test for common paediatric bacterial meningitis pathogens.

RESULTS

A total of 708 patients with abnormal CSF were identified, 89 of whom had a bacterial pathogen confirmed. Hib accounted for the majority of bacteriologically confirmed cases, 62 (70%), while Streptococcus pneumoniae and group B Streptococcus were identified in 12 (13%) and seven (8%) cases, respectively. The other eight cases were a mix of other bacteria. The proportion of abnormal CSF and probable bacterial meningitis that was caused by Hib was 74 and 58 per cent lower at Christian Medical College (CMC), Vellore, which had a 41 per cent coverage of Hib-CV among all suspected meningitis cases, compared to the combined average proportion at the other three centres where a coverage between 1 and 8 per cent was seen (P<0.001 and P= 0.05, respectively).

INTERPRETATION & CONCLUSIONS

Hib was found to be the predominant cause of bacterial meningitis in young children in diverse geographic locations in India. Possible indications of herd immunity was seen at CMC compared to sites with low immunization coverage with Hib-CV. As Hib is the most common pathogen in bacterial meningitis, Hib-CV would have a large impact on bacterial meningitis in Indian children.

Vaccines today, vaccines tomorrow: a perspective

Vaccines are considered as one of the major contributions of the 20th century and one of the most cost effective public health interventions. The International Vaccine Institute has as a mission to discover, develop and deliver new and improved vaccines against infectious diseases that affects developing nations. If Louis Pasteur is known across the globe, vaccinologists like Maurice Hilleman, Jonas Salk and Charles Mérieux are known among experts only despite their contribution to global health. Thanks to a vaccine, smallpox has been eradicated, polio has nearly disappeared, Haemophilus influenzae B, measles and more recently meningitis A are controlled in many countries. While a malaria vaccine is undergoing phase 3, International Vaccine Institute, in collaboration with an Indian manufacturer has brought an oral inactivated cholera vaccine to pre-qualification. The field of vaccinology has undergone major changes thanks to philanthropists such as Bill and Melinda Gates, initiatives like the Decade of Vaccines and public private partnerships. Current researches on vaccines have more challenging targets like the dengue viruses, malaria, human immunodeficiency virus, the respiratory syncytial virus and nosocomial diseases. Exciting research is taking place on new adjuvants, nanoparticles, virus like particles and new route of administration. An overcrowded infant immunization program, anti-vaccine groups, immunizing a growing number of elderlies and delivering vaccines to difficult places are among challenges faced by vaccinologists and global health experts.

Antibody persistence of two pentavalent DTwP-HB-Hib vaccines to the age of 15-18 months, and response to the booster dose of quadrivalent DTwP-Hib vaccine

OBJECTIVES

Antibody persistence in children following three doses of primary vaccination with diphtheria, tetanus, whole-cell-pertussis (DTwP), hepatitis B, and Haemophilus influenzae type b (Hib) vaccines (SIIL Pentavac vaccine vs. Easyfive(®) of Panacea Biotec), and response to the booster dose of DTwP-Hib (Quadrovax(®)) vaccine.

METHODS

Children who completed their primary immunization were assessed for antibodies at 15-18 months of age, and then given a booster dose of DTwP-Hib vaccine. Reactogenicity and safety of the booster dose was evaluated.

RESULTS

Both pentavalent vaccines demonstrated a good immune response at 15-18 months. Following the booster dose, all vaccinated subjects achieved protective titers against diphtheria, tetanus and Hib, whereas the response to pertussis antigen was ~78%. Fever and irritability was noted in 24%, local pain in 51%, and swelling in 36% of the children following booster dose.

CONCLUSIONS

Primary immunization with either pentavalent vaccine induced an excellent immunity lasting till the second year of life. A booster dose with DTwP-Hib (Quadrovax(®)) vaccine effectuated a good anamnestic response to all vaccine components, being specially strong for Hib in children previously vaccinated with SIIL liquid pentavalent vaccine (Pentavac(®)). Also, the safety profile of SIIL quadrivalent vaccine (Quadrovax(®)) administered as booster dose was acceptable.

Variations in mortality in children admitted with pneumonia to Kenyan hospitals

Background

The existing case fatality estimates of inpatient childhood pneumonia in developing countries are largely from periods preceding routine use of conjugate vaccines for infant immunization and such primary studies rarely explore hospital variations in mortality. We analysed case fatality rates of children admitted to nine Kenyan hospitals with pneumonia during the era of routine infant immunization with Hib conjugate vaccine to determine if significant variations exist between hospitals.

Methods

Pneumonia admissions and outcomes in paediatric wards are described using data collected over two time periods: a one-year period (2007–2008) in nine hospitals, and data from a 9.25-year period (1999-March 2008) in one of the participating hospitals. Hospital case fatality rates for inpatient pneumonia during 2007 to 2008 were modeled using a fixed effect binomial regression model with a logit link. Using an interrupted time series design, data from one hospital were analysed for trends in pneumonia mortality during the period between 1997 and March 2008.

Results

Overall, 195 (5.9%) children admitted to all 9 hospitals with pneumonia from March 2007 to March 2008 died in hospital. After adjusting for child’s sex, comorbidity, and hospital effect, mortality was significantly associated with child’s age (p<0.001) and pneumonia severity (p<0.001). There was evidence of significant variations in mortality between hospitals (LR χ² = 52.19; p<0.001). Pneumonia mortality remained stable in the periods before (trend −0.03, 95% CI −0.1 to 0.02) and after Hib introduction (trend 0.04, 95% CI −0.04 to 0.11).

Conclusions

There are important variations in hospital-pneumonia case fatality in Kenya and these variations are not attributed to temporal changes. Such variations in mortality are not addressed by existing epidemiological models and need to be considered in allocating resources to improve child health.

Haemophilus influenzae type b conjugate vaccines - a South African perspective

Introduction of Hib vaccine is known to positively impact on reduction of both morbidity and mortality in children less than 5 years of age. Incorporation of this vaccine into a National EPI, however, does come at a significant cost, which is especially important in non-GAVI funded countries. Compounded reduction in response in certain patient populations and possible indication of booster doses further impacts on cost-benefit analyses. Despite these issues, South Africa has supplied Hib vaccine as part of the National EPI in the form of a combination vaccine, Pentaxim, which combines Hib with Diphtheria, Tetanus, acellular Pertussis (DTP) and Poliomyelitis since 2009. Prior to this, another combination vaccine was utilized containing Hib and DTP. This has subsequently lead to a significant reduction in invasive Hib disease post-introduction, therefore largely justifying utilization.

Haemophilus influenzae Type b Meningitis in the Short Period after Vaccination: A Reminder of the Phenomenon of Apparent Vaccine Failure

We present two cases of bacterial meningitis caused by Haemophilus influenzae type b (Hib) which developed a few days after conjugate Hib vaccination. This phenomenon of postimmunization provocative time period is reviewed and discussed. These cases serve as a reminder to clinicians of the risk, albeit rare, of invasive Hib disease in the short period after successful immunization.

Treatment failure among Kenyan children with severe pneumonia--a cohort study

BACKGROUND

Pneumonia is the leading cause of childhood mortality worldwide. The World Health Organization recommends presumptive treatment based on clinical syndromes. Recent studies raise concerns over the frequency of treatment failure in Africa.

METHODS

We applied a definition of treatment failure to data prospectively collected from children who were 2-59 months of age with severe, or very severe, pneumonia admitted to Kilifi District Hospital, Kenya, from May 2007 through May 2008 and treated using World Health Organization guidelines. The primary outcome was treatment failure at 48 hours.

RESULTS

Of 568 children, median age 11 months, 165 (29%) had very severe pneumonia, 30 (5.3%) a positive HIV test and 62 (11%) severe malnutrition. One hundred eleven (20%; 95% confidence interval: 17-23%) children failed treatment at 48 hours and 34 (6.0%) died; 22 (65%) deaths occurred before 48 hours. Of 353 children with severe pneumonia, without HIV or severe malnutrition, 42 (12%) failed to respond at 48 hours, 15 (4.3%) failed at 5 days and 1 child (0.3%) died. Among 215 children with either severe pneumonia complicated by HIV or severe malnutrition, or very severe pneumonia, 69 (32%) failed to treatment at 48 hours, 47 (22%) failed at 5 days and 33 (16%) died. Treatment failure at 48 hours was associated with shock, bacteremia, very severe pneumonia, oxygen saturation in hemoglobin <95%, severe malnutrition, HIV and age <1 year in multivariable models.

CONCLUSIONS

In this setting, few children with uncomplicated severe pneumonia fail treatment or die under current guidelines. Deaths mainly occurred early and may be reduced by improving prevention, prehospital care and treatment of sepsis.

A preliminary study of pneumonia etiology among hospitalized children in Kenya

BACKGROUND

Pneumonia is the leading cause of childhood death in the developing world. Higher-quality etiological data are required to reduce this mortality burden.

METHODS

We conducted a case-control study of pneumonia etiology among children aged 1-59 months in rural Kenya. Case patients were hospitalized with World Health Organization-defined severe pneumonia (SP) or very severe pneumonia (VSP); controls were outpatient children without pneumonia. We collected blood for culture, induced sputum for culture and multiplex polymerase chain reaction (PCR), and obtained oropharyngeal swab specimens for multiplex PCR from case patients, and serum for serology and nasopharyngeal swab specimens for multiplex PCR from case patients and controls.

RESULTS

Of 984 eligible case patients, 810 (84%) were enrolled in the study; 232 (29%) had VSP. Blood cultures were positive in 52 of 749 case patients (7%). A predominant potential pathogen was identified in sputum culture in 70 of 417 case patients (17%). A respiratory virus was detected by PCR from nasopharyngeal swab specimens in 486 of 805 case patients (60%) and 172 of 369 controls (47%). Only respiratory syncytial virus (RSV) showed a statistically significant association between virus detection in the nasopharynx and pneumonia hospitalization (odds ratio, 12.5; 95% confidence interval, 3.1-51.5). Among 257 case patients in whom all specimens (excluding serum specimens) were collected, bacteria were identified in 24 (9%), viruses in 137 (53%), mixed viral and bacterial infection in 39 (15%), and no pathogen in 57 (22%); bacterial causes outnumbered viral causes when the results of the case-control analysis were considered.

CONCLUSIONS

A potential etiology was detected in >75% of children admitted with SP or VSP. Except for RSV, the case-control analysis did not detect an association between viral detection in the nasopharynx and hospitalization for pneumonia.

The Pneumonia Etiology Research for Child Health Project: a 21st century childhood pneumonia etiology study

The Pneumonia Etiology Research for Child Health (PERCH) project is a 7-country, standardized, comprehensive evaluation of the etiologic agents causing severe pneumonia in children from developing countries. During previous etiology studies, between one-quarter and one-third of patients failed to yield an obvious etiology; PERCH will employ and evaluate previously unavailable innovative, more sensitive diagnostic techniques. Innovative and rigorous epidemiologic and analytic methods will be used to establish the causal association between presence of potential pathogens and pneumonia. By strategic selection of study sites that are broadly representative of regions with the greatest burden of childhood pneumonia, PERCH aims to provide data that reflect the epidemiologic situation in developing countries in 2015, using pneumococcal and Haemophilus influenzae type b vaccines. PERCH will also address differences in host, environmental, and/or geographic factors that might determine pneumonia etiology and, by preserving specimens, will generate a resource for future research and pathogen discovery.

Dose-specific efficacy of Haemophilus influenzae type b conjugate vaccines: a systematic review and meta-analysis of controlled clinical trials

Global coverage of infant Haemophilus influenzae type b (Hib) vaccination has increased considerably during the past decade, partly due to GAVI Alliance donations of the vaccine to low-income countries. In settings where large numbers of children receive only one or two vaccine doses rather than the recommended three doses, dose-specific efficacy estimates are needed to predict impact. The objective of this meta-analysis is to determine Hib vaccine efficacy against different clinical outcomes after receiving one, two or three doses of vaccine. Studies were eligible for inclusion if a prospective, controlled design had been used to evaluate commercially available Hib conjugate vaccines. Eight studies were included. Pooled vaccine efficacies against invasive Hib disease after one, two or three doses of vaccine were 59%, 92% and 93%, respectively. The meta-analysis provides robust estimates for use in decision-analytical models designed to predict the impact of Hib vaccine.

Profile: The Kilifi Health and Demographic Surveillance System (KHDSS)

Summary The Kilifi Health and Demographic Surveillance System (KHDSS), located on the Indian Ocean coast of Kenya, was established in 2000 as a record of births, pregnancies, migration events and deaths and is maintained by 4-monthly household visits. The study area was selected to capture the majority of patients admitted to Kilifi District Hospital. The KHDSS has 260 000 residents and the hospital admits 4400 paediatric patients and 3400 adult patients per year. At the hospital, morbidity events are linked in real time by a computer search of the population register. Linked surveillance was extended to KHDSS vaccine clinics in 2008.

KHDSS data have been used to define the incidence of hospital presentation with childhood infectious diseases (e.g. rotavirus diarrhoea, pneumococcal disease), to test the association between genetic risk factors (e.g. thalassaemia and sickle cell disease) and infectious diseases, to define the community prevalence of chronic diseases (e.g. epilepsy), to evaluate access to health care and to calculate the operational effectiveness of major public health interventions (e.g. conjugate Haemophilus influenzae type b vaccine). Rapport with residents is maintained through an active programme of community engagement. A system of collaborative engagement exists for sharing data on survival, morbidity, socio-economic status and vaccine coverage.

Evaluation of haemophilus influenzae type b vaccine for routine immunization in Nepali infants

BACKGROUND

Haemophilus influenzae type b (Hib) carriage and disease studies in Nepali children suggest a significant burden of infection. Hib conjugate vaccines (HibCV) do not have uniform immunogenicity between populations. We determined the immunogenicity of HibCV in Nepali infants, before its introduction into the routine immunization schedule.

METHODS

Ninety infants recruited at Patan Hospital, Kathmandu, received 3 doses of the HibCV with routine immunizations (diphtheria, tetanus, whole cell pertussis-hepatitis B vaccine + oral polio vaccine) at 6, 10 and 14 weeks of age, and a HibCV booster at 52 weeks. Anti-polyribosylribitol phosphate (PRP) concentrations were measured at 18, 52 and 56 weeks, and the antibody persistence at 52 weeks was compared with antibody values in unimmunized controls (n = 30).

RESULTS

After 3 doses of primary immunizations, at 18 weeks of age (n = 74), all infants had anti-PRP concentrations above the accepted thresholds for short- and long-term protection (0.15 and 1.0 µg/mL, respectively). At 1 year of age, before administration of the booster of HibCV, the anti-PRP geometric mean antibody concentration was 2.76 µg/mL (confidence interval: 1.88-4.07) in sera from the immunized children compared with 0.11 µg/mL (95% confidence interval: 0.08-0.17) in the nonimmunized control group (n = 30). Twenty-seven percent (20/74) of participants, however, had anti-PRP concentrations <1.0 µg/mL. Four weeks after the booster dose of HibCV, 98.5% of infants had anti-PRP concentrations above 1.0 µg/mL.

CONCLUSION

Immunization with HibCV given as part of the Expanded Program on Immunization schedule in Nepal elicits robust antibody responses. Though the antibody wanes during the first year of life, most 1-year-old infants remain protected and respond robustly to a booster dose of the vaccine.

Estimating individual exposure to malaria using local prevalence of malaria infection in the field

Background

Heterogeneity in malaria exposure complicates survival analyses of vaccine efficacy trials and confounds the association between immune correlates of protection and malaria infection in longitudinal studies. Analysis may be facilitated by taking into account the variability in individual exposure levels, but it is unclear how exposure can be estimated at an individual level.

Method and Findings

We studied three cohorts (Chonyi, Junju and Ngerenya) in Kilifi District, Kenya to assess measures of malaria exposure. Prospective data were available on malaria episodes, geospatial coordinates, proximity to infected and uninfected individuals and residence in predefined malaria hotspots for 2,425 individuals. Antibody levels to the malaria antigens AMA1 and MSP1₁₄₂ were available for 291 children from Junju. We calculated distance-weighted local prevalence of malaria infection within 1 km radius as a marker of individual's malaria exposure. We used multivariable modified Poisson regression model to assess the discriminatory power of these markers for malaria infection (i.e. asymptomatic parasitaemia or clinical malaria). The area under the receiver operating characteristic (ROC) curve was used to assess the discriminatory power of the models. Local malaria prevalence within 1 km radius and AMA1 and MSP1₁₄₂ antibodies levels were independently associated with malaria infection. Weighted local malaria prevalence had an area under ROC curve of 0.72 (95%CI: 0.66–0.73), 0.71 (95%CI: 0.69–0.73) and 0.82 (95%CI: 0.80–0.83) among cohorts in Chonyi, Junju and Ngerenya respectively. In a small subset of children from Junju, a model incorporating weighted local malaria prevalence with AMA1 and MSP1₁₄₂ antibody levels provided an AUC of 0.83 (95%CI: 0.79–0.88).

Conclusion

We have proposed an approach to estimating the intensity of an individual's malaria exposure in the field. The weighted local malaria prevalence can be used as individual marker of malaria exposure in malaria vaccine trials and longitudinal studies of natural immunity to malaria.

A challenge to appropriate antibiotic use in children with respiratory infections: a 5-year single-institution experience

BACKGROUND

We have studied the rate of emergence of antibiotic-resistant Streptococcus pneumoniae (S. pneumoniae) and Haemophilus influenzae (H. influenzae) and the subsequent antibiotic use in host patients of those isolates at the Department of Pediatrics, Soma General Hospital, Fukushima. Moreover, we carried out several studies investigating the risks and benefits of antibiotic-free treatment for children with respiratory infections. In this report, we summarize our research and suggest better treatment options for pediatric patients with respiratory infections.

METHODS

We investigated the necessity of antibiotic use in the treatment of pediatric inpatients with respiratory syncytial virus (RSV) infection, and tested our hypothesis that antibiotic-free treatment for common cold will reduce the number of resistant S. pneumoniae strains in the pediatric nasopharynx. Therefore, we restricted prescribing antibiotics for pediatric patients with respiratory infections. The rates of resistant S. pneumoniae and H. influenzae and the medication history of the host patients before and after the intervention were compared.

RESULTS

We found that most of the RSV-infected patients recovered without antibiotic treatment, and that the antibiotic-free treatment inhibited the emergence of antibiotic-resistant strains. The rate of penicillin-resistant S. pneumoniae decreased but the rate of ampicillin-resistant H. influenzae did not change significantly during the study.

CONCLUSION

We concluded that patients with respiratory infections can be treated without antibiotics, under careful examination and observation. Continued monitoring of such new interventions as well as recommending their use to other caregivers and physicians will help inhibit the spread of resistant strains.

Vaccination with Haemophilus influenzae type b conjugate vaccine reduces bacterial meningitis in Morocco

INTRODUCTION

Haemophilus influenzae type b (Hib) is a leading cause of bacterial meningitis and pneumonia and can be prevented by Hib vaccine. We conducted a vaccine impact evaluation to support continued use of Hib vaccine in Morocco following introduction in 2007.

METHODS

Bacterial meningitis surveillance data from 2004 to 2009 were obtained from 11 sentinel hospitals located in eight provinces and one prefecture in Morocco to examine Hi meningitis reporting for cases aged <5 years. We defined the years of 2004-2006 as the pre-vaccine period and 2008-2009 as the post-vaccine period and compared the mean annual number of confirmed Hi meningitis cases for these time periods using a Chi-square test. We calculated the minimum incidence of Hi meningitis during the evaluation period in Grand Casa Prefecture, where the catchment population could be estimated.

RESULTS

From 2004 to 2009, 1844 suspected meningitis case-patients aged <5 years were reported; 354 (19.2%) were confirmed with bacterial meningitis, including 105 (29.7%) Hi cases. The mean annual number of confirmed Hi meningitis cases decreased by 75%, from 24 in the pre-vaccine period to 6 during the post-vaccine period (p<0.001). Assuming Hi cases with unknown age were <5 years of age, the estimated minimum incidence of confirmed Hi meningitis in Grand Casa Prefecture decreased by 93%, from 15 cases per 100,000 children in the pre-vaccine period to 1 case per 100,000 children in the post-vaccine period.

CONCLUSION

Hib vaccine introduction likely significantly reduced the occurrence of Hi meningitis among children aged <5 years at the 11 sentinel hospitals included in this evaluation in Morocco, suggesting that continued use of Hib vaccine in Morocco would be beneficial.

Mortality from bacterial meningitis in children in Kosovo

Bacterial meningitis is a severe infection responsible for high mortality. This prospective study of 277 pediatric bacterial meningitis cases was done to identify factors predicting death in children <16 years of age living and treated in a limited-resources country (Kosovo). Of the 277 children enrolled, 60 patients (22%) developed neurologic complications, and 15 children died (5%). The following variables were strongly correlated with mortality: altered mental status on admission (relative risk [RR] = 29.9), presentation of the initial cerebrospinal fluid as thick pus (RR = 29.9), prehospital seizures (RR = 23.5) and their recurrence >24 hours after admission (RR = 11.5), age <1 month (RR = 19.3), the use of inotropic agents (RR = 11.5), and admission after 5 days' duration of illness (P < .001). The mortality rate in children in Kosovo is similar to those reported from developing countries, and this is most likely due to the unfavorable living conditions.

Severe soft tissue infection of the lower extremity caused by Haemophilus influenzae (serotype f, biotype II) in an adult patient

The infection caused by non-b-type Haemophilus influenzae has been increasing in this Hib (H.influenzae serotype b) vaccination era. H.influenzae serotype f (Hif) is considered as one of those emerging pathogens. In general, H.influenzae is a common pathogen of such as pneumonia, otitis media, and meningitis, but is rare in soft tissue infection, especially at the extremity. We report a rare case of severe soft tissue infection caused by Hif which occurred at the lower extremity of immunocompetent adult patient.

Changing trends in incidence and aetiology of childhood acute non-traumatic coma over a period of changing malaria transmission in rural coastal Kenya: a retrospective analysis

OBJECTIVES

Recent changes in malaria transmission have likely altered the aetiology and outcome of childhood coma in sub-Saharan Africa. The authors conducted this study to examine change in incidence, aetiology, clinical presentation, mortality and risk factors for death in childhood non-traumatic coma over a 6-year period.

DESIGN

Retrospective analysis of prospectively collected data.

SETTING

Secondary level health facility: Kilifi, Coast, Kenya.

PARTICIPANTS

Children aged 9 months to 13 years admitted with acute non-traumatic coma (Blantyre Coma Score =2) between January 2004 and December 2009 to Kilifi District Hospital, Kenya.

EXCLUSION CRITERIA

delayed development, epilepsy and sickle cell disease.

RESULTS

During the study period, 665 children (median age 32 (IQR 20-46) months; 46% were girls) were admitted in coma. The incidence of childhood coma declined from 93/100 000 children in 2004 to 44/100 000 children in 2009. There was a 64% overall drop in annual malaria-positive coma admissions and a 272% overall increase in annual admissions with encephalopathies of undetermined cause over the study period. There was no change in case death of coma. Vomiting, breathing difficulties, bradycardia, profound coma (Blantyre Coma Score=0), bacteraemia and clinical signs of meningitis were associated with increased risk of death. Seizures within 24 h prior to admission, and malaria parasitaemia, were independently associated with survival, unchanging during the study period.

CONCLUSION

The decline in the incidence and number of admissions of childhood acute non-traumatic coma is due to decreased malaria transmission. The relative and absolute increase in admissions of encephalopathy of undetermined aetiology could represent aetiologies previously masked by malaria or new aetiologies.

A phase III randomized, controlled study to assess and compare the immunogenicity and tolerability of single and multi-dose vials of DTwP-Hib, a fully liquid quadravalent vaccine and their comparison with TETRAct-Hib vaccine in Indian infants aged 6-14 weeks

Both WHO and IAP encourage using combination vaccines, wherever feasible. The phase III trial reported here was conducted to assess and compare the immunogenicity, tolerability and safety of two quadravalent vaccines, Quadrovax(®) (new vaccine), and TETRAct-Hib(®) (available in the market) in a multicentre study, in India. In all, 361 infants aged 6-8 weeks were enrolled, out of which 339 completed the study. The vaccination was done at 6-10-14 weeks following EPI/WHO recommended immunization schedule. Blood samples were collected prior to the administration of first dose and one month after the third dose. Postvaccination, geometric mean titres for each component did not differ significantly between the single dose vial and multi dose vial subgroups and among the two study groups. Adverse events observed were within the range quoted in literature. Quadrovax(®) vaccine manufactured by SIIL was found to be safe, immunogenic and non-inferior to the comparator vaccine. The quadravalent vaccine is best recommended in the second year of life when children receive their booster dose at 15-18 months. It can be given to infants during primary immunization series at 6, 10 and 14 weeks of age when Hepatitis B vaccine is given in a separate arm or to infants at 10 weeks who receive the Hepatitis B vaccine separately following the 0, 6 and 14 weeks or 0, 1 and 6 months schedule.

Accelerating introduction of new vaccines: barriers to introduction and lessons learned from the recent Haemophilus influenzae type B vaccine experience

Adoption of new vaccines in developing countries is critical to reducing child mortality and meeting Millennium Development Goal 4. However, such introduction has historically suffered from significant delays that can be attributed to various factors including (i) lack of recognition of the value of a vaccine, (ii) factors related to weak health systems, and (iii) policy considerations. Recently, the Global Alliance for Vaccines and Immunization (GAVI) supported efforts to accelerate the introduction of Haemophilus influenzae type b (Hib) vaccines in developing countries, which resulted in a significant surge in vaccine adoption by these countries. The experience with Hib vaccines, as well as similar efforts by GAVI to support the introduction of new pneumococcal and rotavirus vaccines, provides a strategy for new vaccine adoption that is reviewed in this paper, providing a useful model to help accelerate the uptake of other life-saving vaccines. This strategy addresses barriers for vaccine adoption by focusing on three major areas: (i) communications to increase awareness about the various factors needed for evidence-based decisions that meet a country's health goals; (ii) research activities to answer key questions that support vaccine introduction and long-term programme sustainability; and (iii) coordination with the various stakeholders at global, regional and country levels to ensure successful programme implementation.

Relation between falciparum malaria and bacteraemia in Kenyan children: a population-based, case-control study and a longitudinal study

BACKGROUND

Many investigators have suggested that malaria infection predisposes individuals to bacteraemia. We tested this hypothesis with mendelian randomisation studies of children with the malaria-protective phenotype of sickle-cell trait (HbAS).

METHODS

This study was done in a defined area around Kilifi District Hospital, Kilifi, Kenya. We did a matched case-control study to identify risk factors for invasive bacterial disease, in which cases were children aged 3 months to 13 years who were admitted to hospital with bacteraemia between Sept 16, 1999, and July 31, 2002. We aimed to match two controls, by age, sex, location, and time of recruitment, for every case. We then did a longitudinal case-control study to assess the relation between HbAS and invasive bacterial disease as malaria incidence decreased. Cases were children aged 0-13 years who were admitted to hospital with bacteraemia between Jan 1, 1999, and Dec 31, 2007. Controls were born in the study area between Jan 1, 2006, and June 23, 2009. Finally, we modelled the annual incidence of bacteraemia against the community prevalence of malaria during 9 years with Poisson regression.

RESULTS

In the matched case-control study, we recruited 292 cases-we recruited two controls for 236, and one for the remaining 56. Sickle-cell disease, HIV, leucocyte haemozoin pigment, and undernutrition were positively associated with bacteraemia and HbAS was strongly negatively associated with bacteraemia (odds ratio 0·36; 95% CI 0·20-0·65). In the longitudinal case-control study, we assessed data from 1454 cases and 10,749 controls. During the study period, the incidence of admission to hospital with malaria per 1000 child-years decreased from 28·5 to 3·45, with a reduction in protection afforded by HbAS against bacteraemia occurring in parallel (p=0·0008). The incidence of hospital admissions for bacteraemia per 1000 child-years also decreased from 2·59 to 1·45. The bacteraemia incidence rate ratio associated with malaria parasitaemia was 6·69 (95% CI 1·31-34·3) and, at a community parasite prevalence of 29% in 1999, 62% (8·2-91) of bacteraemia cases were attributable to malaria.

INTERPRETATION

Malaria infection strongly predisposes individuals to bacteraemia and can account for more than half of all cases of bacteraemia in malaria-endemic areas. Interventions to control malaria will have a major additional benefit by reducing the burden of invasive bacterial disease.

FUNDING

Wellcome Trust.

Pneumococcal conjugate vaccine given shortly after birth stimulates effective antibody concentrations and primes immunological memory for sustained infant protection

Immunization of Kenyan newborns with 7-valent pneumococcal conjugate vaccine is safe and immunogenic. Compared with the Expanded Programme on Immunization schedule beginning at 6 weeks, it stimulates similar antibody concentrations at 18 weeks and induces equal responses to a 9-month booster dose.

Background. In developing countries, newborn immunization with pneumococcal conjugate vaccines (PCVs) could protect young infants who are at high risk of invasive pneumococcal disease (IPD) but might lead to immune tolerance.

Methods. In a randomized trial, young infants received 7-valent PCV at 6, 10, and 14 weeks (Expanded Programme on Immunization [EPI] group) or 0, 10, and 14 weeks (newborn group). Safety was monitored actively at 2–7 days and then passively. Serum samples obtained at birth and 6, 10, 14, 18, 36, and 37 weeks were assayed by enzyme-linked immunosorbent assay for anticapsular immunoglobulin G concentration and avidity. Infants were boosted with either 7-valent PCV or one-fifth dose of pneumococcal polysaccharide vaccine at 36 weeks. Nasopharyngeal swab samples were obtained at 18 and 36 weeks.

Results. Three-hundred neonates and young infants were enrolled. Newborn vaccination was well tolerated. Adverse events occurred equally in each group; none was related to immunization. One infant, immunized at birth, died of unrelated neonatal sepsis. At 18 weeks, protective concentrations (≥0.35 μg/mL) were achieved against each serotype by ≥87% of infants with no significant differences between groups. Geometric mean concentrations were higher in the EPI group for serotypes 4, 9V, 18C, and 19F at 18 weeks and for serotype 4 at 36 weeks. Avidity was greater in the newborn group for serotypes 4, 6B, and 19F at 18 weeks and for serotype 19F at 36 weeks. Booster responses and vaccine-type/nonvaccine-type carriage prevalence did not differ between groups.

Conclusions. PCV was safe, immunogenic, and primed for memory when given at birth. There was no evidence of immune tolerance. Vaccination beginning at birth offers an alternative to control IPD in vulnerable young infants.

'All her children are born that way': gendered experiences of stigma in families affected by sickle cell disorder in rural Kenya

OBJECTIVES

To explore early experiences of sickle cell disorder (SCD) in families with a young affected child, and the way these experiences influence relations within families. To consider ways in which stigma could be counteracted in health and research programmes in sub Saharan Africa.

DESIGN

A qualitative study was conducted in a rural area of coastal Kenya including in-depth interviews with 13 families affected by SCD and 12 staff of a local biomedical research progamme. Purposive selection aimed to maximize diversity in socioeconomic and educational status, religion, severity of illness burden and religion amongst families and draw on relevant experience for staffs. Interviews were recorded, transcribed and analysed using the constant comparative method for family interviews and a thematic framework approach for staff data.

RESULTS

Low initial recognition of SCD and its cause were associated with lay practices of surveillance within affected families, contributing to stigmatisation that occurred independently of genetic knowledge. Blame was often placed on mothers, including a risk of blame for misaligned paternity. Mothers are often particularly affected by SCD through the loss of independent livelihoods and their limited options in coping with this chronic condition.

CONCLUSIONS

Mothers of children with SCD were particularly vulnerable to stigmatisation within families, with underlying structural influences that suggest these findings may apply to other similar settings in Africa, and have relevance for other genetic conditions. The potential, nature and form of stigmatisation point to the role of effective communication and SCD management in addressing for blame and discriminative effects of having a child with SCD. The findings highlight the importance of broader social programmes targeting underlying gender and economic inequalities.

Effectiveness of haemophilus influenzae type B conjugate vaccine for prevention of meningitis in Senegal

A total of 24 cases of hospitalized, laboratory-confirmed Haemophilus influenzae type b (Hib) meningitis were identified through a regional pediatric bacterial meningitis surveillance system. Each case was matched by age and residence to 4 neighborhood controls. The adjusted vaccine effectiveness for ≥ 2 doses was 95.8% (95% confidence interval, 67.9%-99.4%). Hib vaccine appears to be highly effective in preventing Hib meningitis in Senegal.

Acute seizures attributable to falciparum malaria in an endemic area on the Kenyan coast

Falciparum malaria is an important cause of acute symptomatic seizures in children admitted to hospitals in sub-Saharan Africa, and these seizures are associated with neurological disabilities and epilepsy. However, it is difficult to determine the proportion of seizures attributable to malaria in endemic areas since a significant proportion of asymptomatic children have malaria parasitaemia. We studied children aged 0–13 years who had been admitted with a history of seizures to a rural Kenyan hospital between 2002 and 2008. We examined the changes in the incidence of seizures with the reduction of malaria. Logistic regression was used to model malaria-attributable fractions for seizures (the proportion of seizures caused by malaria) to determine if the observed decrease in acute symptomatic seizures was a measure of seizures that are attributable to malaria. The overall incidence of acute symptomatic seizures over the period was 651/100 000/year (95% confidence interval 632–670) and it was 400/100 000/year (95% confidence interval 385–415) for acute complex symptomatic seizures (convulsive status epilepticus, repetitive or focal) and 163/100 000/year (95% confidence interval 154–173) for febrile seizures. From 2002 to 2008, the incidence of all acute symptomatic seizures decreased by 809/100 000/year (69.2%) with 93.1% of this decrease in malaria-associated seizures. The decrease in the incidence of acute complex symptomatic seizures during the period was 111/100 000/year (57.2%) for convulsive status epilepticus, 440/100 000/year (73.7%) for repetitive seizures and 153/100 000/year (80.5%) for focal seizures. The adjusted malaria-attributable fractions for seizures with parasitaemia were 92.9% (95% confidence interval 90.4–95.1%) for all acute symptomatic seizures, 92.9% (95% confidence interval 89.4–95.5%) for convulsive status epilepticus, 93.6% (95% confidence interval 90.9–95.9%) for repetitive seizures and 91.8% (95% confidence interval 85.6–95.5%) for focal seizures. The adjusted malaria-attributable fractions for seizures in children above 6 months of age decreased with age. The observed decrease in all acute symptomatic seizures (809/100 000/year) was similar to the predicted decline (794/100 000/year) estimated by malaria-attributable fractions at the beginning of the study. In endemic areas, falciparum malaria is the most common cause of seizures and the risk for seizures in malaria decreases with age. The reduction in malaria has decreased the burden of seizures that are attributable to malaria and this could lead to reduced neurological disabilities and epilepsy in the area.

Working with Concepts: The Role of Community in International Collaborative Biomedical Research

The importance of communities in strengthening the ethics of international collaborative research is increasingly highlighted, but there has been much debate about the meaning of the term 'community' and its specific normative contribution. We argue that 'community' is a contingent concept that plays an important normative role in research through the existence of morally significant interplay between notions of community and individuality. We draw on experience of community engagement in rural Kenya to illustrate two aspects of this interplay: (i) that taking individual informed consent seriously involves understanding and addressing the influence of communities in which individuals' lives are embedded; (ii) that individual participation can generate risks and benefits for communities as part of the wider implications of research. We further argue that the contingent nature of a community means that defining boundaries is generally a normative process itself, with ethical implications. Community engagement supports the enactment of normative roles; building mutual understanding and trust between researchers and community members have been important goals in Kilifi, requiring a broad range of approaches. Ethical dilemmas are continuously generated as part of these engagement activities, including the risks of perverse outcomes related to existing social relations in communities and conditions of 'half knowing' intrinsic to processes of developing new understandings.

Hospital surveillance of childhood bacterial meningitis in Senegal and the introduction of Haemophilus influenzae type b conjugate vaccine

Bacterial meningitis is an important cause of morbidity and mortality in children living in low-resource settings. Pediatric bacterial meningitis cases < 5 years of age were identified through a regional hospital surveillance system for 3 years after introduction of routine immunization with Haemophilus influenzae type b (Hib) conjugate vaccine in Senegal in July 2005. Cases from the national pediatric hospital were also tracked from 2002 to 2008. The regional surveillance system recorded 1,711 suspected pediatric bacterial meningitis cases. Of 214 laboratory-confirmed cases, 108 (50%) were caused by Streptococcus pneumoniae, 42 (20%) to Hib, and 13 (6%) to Neisseria meningitidis. There was a 98% reduction in the number of hospitalized Hib meningitis cases from Dakar Region in 2008 compared with 2002. The surveillance system provides important information to the Ministry of Health as they consider self-funding Hib vaccine and introducing pneumococcal vaccine.

Primary and booster vaccination in Latin American children with a DTPw-HBV/Hib combination: a randomized controlled trial

BACKGROUND

Diphtheria-tetanus-whole-cell pertussis (DTPw)-based combination vaccines are an attractive option to rapidly achieve high coverage and protection against other important pathogens, such as hepatitis B virus (HBV) and Haemophilus influenzae type B (Hib). To ensure adequate antigen supply, GlaxoSmithKline Biologicals has introduced a new DTPw antigen source and developed a new DTPw-HBV/Hib combination vaccine containing a reduced amount of Hib polyribosylribitol phosphate (PRP). This study was undertaken to compare the immunogenicity and reactogenicity of this new DTPw-HBV/Hib vaccine with a licensed DTPw-HBV/Hib vaccine (Tritanrix™-HBV/Hib).

METHODS

This was a randomized, partially-blind, multicenter study in three countries in Latin America (Argentina, Chile and Nicaragua). Healthy children received either the new DTPw-HBV/Hib vaccine (1 of 3 lots; n = 439; double-blind) or Tritanrix™-HBV/Hib (n = 146; single-blind) co-administered with oral poliovirus vaccine (OPV) at 2, 4 and 6 months, with a booster dose at 18-24 months.

RESULTS

One month after the end of the 3-dose primary vaccination course, the new DTPw-HBV/Hib vaccine was non-inferior to Tritanrix™-HBV/Hib in terms of seroprotection/vaccine response rates for all component antigens; ≥97.3% and ≥93.9% of subjects in the two groups, respectively, had seroprotective levels of antibodies against diphtheria, tetanus, hepatitis B and Hib and a vaccine response to the pertussis component. Persistence of antibodies against all vaccine antigens was comparable between groups, with marked increases in all antibody concentrations after booster administration in both groups. Both vaccines were generally well-tolerated as primary and booster doses.

CONCLUSIONS

Results confirm the suitability of this new DTPw-HBV/Hib vaccine comprising antigens from a new source and a reduced PRP content for inclusion into routine childhood vaccination programs.

TRIAL REGISTRATION

http://www.clinicaltrials.gov NCT00332566.

An increase in the burden of neonatal admissions to a rural district hospital in Kenya over 19 years

BACKGROUND

Most of the global neonatal deaths occur in developing nations, mostly in rural homes. Many of the newborns who receive formal medical care are treated in rural district hospitals and other peripheral health centres. However there are no published studies demonstrating trends in neonatal admissions and outcome in rural health care facilities in resource poor regions. Such information is critical in planning public health interventions. In this study we therefore aimed at describing the pattern of neonatal admissions to a Kenyan rural district hospital and their outcome over a 19 year period, examining clinical indicators of inpatient neonatal mortality and also trends in utilization of a rural hospital for deliveries.

METHODS

Prospectively collected data on neonates is compared to non-neonatal paediatric (≤ 5 years old) admissions and deliveries' in the maternity unit at Kilifi District Hospital from January 1(st) 1990 up to December 31(st) 2008, to document the pattern of neonatal admissions, deliveries and changes in inpatient deaths. Trends were examined using time series models with likelihood ratios utilised to identify indicators of inpatient neonatal death.

RESULTS

The proportion of neonatal admissions of the total paediatric ≤ 5 years admissions significantly increased from 11% in 1990 to 20% by 2008 (trend 0.83 (95% confidence interval 0.45-1.21). Most of the increase in burden was from neonates born in hospital and very young neonates aged < 7 days. Hospital deliveries also increased significantly. Clinical diagnoses of neonatal sepsis, prematurity, neonatal jaundice, neonatal encephalopathy, tetanus and neonatal meningitis accounted for over 75% of the inpatient neonatal admissions. Inpatient case fatality for all ≤ 5 years declined significantly over the 19 years. However, neonatal deaths comprised 33% of all inpatient death among children aged ≤ 5 years in 1990, this increased to 55% by 2008. Tetanus 256/390 (67%), prematurity 554/1,280(43%) and neonatal encephalopathy 253/778(33%) had the highest case fatality. A combination of six indicators: irregular respiration, oxygen saturation of <90%, pallor, neck stiffness, weight < 1.5 kg, and abnormally elevated blood glucose > 7 mmol/l predicted inpatient neonatal death with a sensitivity of 81% and a specificity of 68%.

CONCLUSIONS

There is clear evidence of increasing burden in neonatal admissions at a rural district hospital in contrast to reducing numbers of non-neonatal paediatrics' admissions aged ≤ 5 years. Though the inpatient case fatality for all admissions aged ≤ 5 years declined significantly, neonates now comprise close to 60% of all inpatient deaths. Simple indicators may identify neonates at risk of death.

Methodology and measurement of the effectiveness of Haemophilus influenzae type b vaccine: systematic review

The use of the highly effective Haemophilus influenzae type b (Hib) conjugate vaccine has increased globally. We review the benefits and limitations of studies measuring Hib vaccine effectiveness (VE). We critically examine the case-control approach by assessing the similarities and differences in methodology and findings and discuss the need for future Hib VE studies. In the absence of good surveillance data, vaccine effectiveness studies can play an important role, particularly with the increasing use of pneumococcal vaccine that has not been well tested under field conditions in less developed countries. However, the effectiveness of Hib vaccine has been well documented so the need for future VE Hib studies is minimal.

Experiences with community engagement and informed consent in a genetic cohort study of severe childhood diseases in Kenya

BACKGROUND

The potential contribution of community engagement to addressing ethical challenges for international biomedical research is well described, but there is relatively little documented experience of community engagement to inform its development in practice. This paper draws on experiences around community engagement and informed consent during a genetic cohort study in Kenya to contribute to understanding the strengths and challenges of community engagement in supporting ethical research practice, focusing on issues of communication, the role of field workers in 'doing ethics' on the ground and the challenges of community consultation.

METHODS

The findings are based on action research methods, including analysis of community engagement documentation and the observations of the authors closely involved in their development and implementation. Qualitative and quantitative content analysis has been used for documentation of staff meetings and trainings, a meeting with 24 community leaders, and 40 large public and 70 small community group meetings. Meeting minutes from a purposive sample of six community representative groups have been analysed using a thematic framework approach.

RESULTS

Field workers described challenges around misunderstandings about research, perceived pressure for recruitment and challenges in explaining the study. During consultation, leaders expressed support for the study and screening for sickle cell disease. In community meetings, there was a common interpretation of research as medical care. Concerns centred on unfamiliar procedures. After explanations of study procedures to leaders and community members, few questions were asked about export of samples or the archiving of samples for future research.

CONCLUSIONS

Community engagement enabled researchers to take account of staff and community opinions and issues during the study and adapt messages and methods to address emerging ethical challenges. Field workers conducting informed consent faced complex issues and their understanding, attitudes and communication skills were key influences on ethical practice. Community consultation was a challenging concept to put into practice, illustrating the complexity of assessing information needs and levels of deliberation that are appropriate to a given study.

Epidemiology, diagnosis, and antimicrobial treatment of acute bacterial meningitis

The epidemiology of bacterial meningitis has changed as a result of the widespread use of conjugate vaccines and preventive antimicrobial treatment of pregnant women. Given the significant morbidity and mortality associated with bacterial meningitis, accurate information is necessary regarding the important etiological agents and populations at risk to ascertain public health measures and ensure appropriate management. In this review, we describe the changing epidemiology of bacterial meningitis in the United States and throughout the world by reviewing the global changes in etiological agents followed by specific microorganism data on the impact of the development and widespread use of conjugate vaccines. We provide recommendations for empirical antimicrobial and adjunctive treatments for clinical subgroups and review available laboratory methods in making the etiological diagnosis of bacterial meningitis. Finally, we summarize risk factors, clinical features, and microbiological diagnostics for the specific bacteria causing this disease.

High mortality from Plasmodium falciparum malaria in children living with sickle cell anemia on the coast of Kenya

Although malaria is widely considered a major cause of death in young children born with sickle cell anemia (SCA) in sub-Saharan Africa, this is poorly quantified. We attempted to investigate this question through 4 large case-control analyses involving 7164 children living on the coast of Kenya. SCA was associated with an increased risk of admission to hospital both with nonmalaria diseases in general (odds ratio [OR] = 4.17; 95% confidence interval [CI], 1.95-8.92; P < .001) and with invasive bacterial diseases in particular (OR = 8.73; 95% CI, 4.51-16.89; P < .001). We found no evidence for a strongly increased risk of either uncomplicated malaria (OR = 0.43; 95% CI, 0.09-2.10; P = .30) or malaria complicated by a range of well-described clinical features of severity (OR = 0.80; 95% CI, 0.25-2.51; P = .70) overall; nevertheless, mortality was considerably higher among SCA than non-SCA children hospitalized with malaria. Our findings highlight both the central role that malaria plays in the high early mortality seen in African children with SCA and the urgent need for better quantitative data. Meanwhile, our study confirms the importance of providing all children living with SCA in malaria-endemic areas with effective prophylaxis.

The causative organisms of bacterial meningitis in Korean children in 1996-2005

Bacterial meningitis remains a serious cause of morbidity and mortality in childhood, despite the availability of effective vaccines against Haemophilus influenzae type b (Hib) or Streptococcus pneumoniae. The purpose of this study was to analyze data on bacterial meningitis cases in Korea from 1996 through 2005. The information of all hospitalized bacteria-proven meningitis cases was obtained from 17 university hospitals nationwide. A total of 402 cases were identified. Of these, 125 (29.9%) cases were neonates. Streptococcus agalactiae was the most common bacteria responsible for 99 (24.6%) of all cases regardless of age, followed by S. pneumoniae for 91 (22.6%) and H. influenzae for 67 (16.7%) patients. The common etiology beyond the neonatal period was S. pneumoniae for 91 (33.0%) followed by H. influenzae for 63 (22.8%) patients. The overall case fatality rate was 9.4%, which was similar with that in 1986-1995. In conclusion, S. agalactiae, S. pneumoniae and H. influenzae were important etiologic agents of bacterial meningitis in children in the last 10 yrs. It is required to establish the preventive strategy of the three bacteria. The nationwide epidemiologic study should be continued to evaluate immunization strategy and efficacy.

The Elimination of Haemophilus influenzae type b meningitis following conjugate vaccine introduction in Senegal

BACKGROUND

Senegal introduced routine infant Haemophilus influenzae type b (Hib) conjugate vaccine during 2005.

METHODS

We evaluated acute bacterial meningitis surveillance data among children 0 to 59 months of age collected during January 2003 to September 2007 at the major pediatric referral hospital in the Dakar Region of Senegal. Hib vaccine effectiveness was assessed using a case-control design.

RESULTS

A total of 1749 children with suspected bacterial meningitis were included in the current study of whom 142 (8%) had Hib identified. Among children less than age 1 year, the average annual Hib meningitis incidence decreased from 22 to 47 per 100,000 during 2003-2005 to 1.4 per 100,000 during 2007, while pneumococcal meningitis incidence remained stable. Before vaccine introduction, calculated incidences varied over 4-fold between districts within the Dakar Region for the years 2003 to 2005. Following use of Hib vaccine, pneumococcus has now become the most common etiology of pediatric acute bacterial meningitis in Dakar region.

CONCLUSIONS

Senegal successfully implemented Hib conjugate vaccine into their routine infant immunization program with a resultant near elimination of Hib meningitis burden.

Viral etiology of severe pneumonia among Kenyan infants and children

CONTEXT

Pneumonia is the leading cause of childhood death in sub-Saharan Africa. Comparative estimates of the contribution of causative pathogens to the burden of disease are essential for targeted vaccine development.

OBJECTIVE

To determine the viral etiology of severe pneumonia among infants and children at a rural Kenyan hospital using comprehensive and sensitive molecular diagnostic techniques.

DESIGN, SETTING, AND PARTICIPANTS

Prospective observational and case-control study during 2007 in a rural Kenyan district hospital. Participants were children aged 1 day to 12 years, residing in a systematically enumerated catchment area, and who either were admitted to Kilifi District Hospital meeting World Health Organization clinical criteria for severe pneumonia or very severe pneumonia; (2) presented with mild upper respiratory tract infection but were not admitted; or (3) were well infants and children attending for immunization.

MAIN OUTCOME MEASURES

The presence of respiratory viruses and the odds ratio for admission with severe disease.

RESULTS

Of 922 eligible admitted patients, 759 were sampled (82% [median age, 9 months]). One or more respiratory viruses were detected in 425 of the 759 sampled (56% [95% confidence interval {CI}, 52%-60%]). Respiratory syncytial virus (RSV) was detected in 260 participants (34% [95% CI, 31%-38%]) and other respiratory viruses were detected in 219 participants (29%; 95% CI, 26%-32%), the most common being Human coronavirus 229E (n = 51 [6.7%]), influenza type A (n = 44 [5.8%]), Parainfluenza type 3 (n = 29 [3.8%]), Human adenovirus (n = 29 [3.8%]), and Human metapneumovirus (n = 23 [3.0%]). Compared with well control participants, detection of RSV was associated with severe disease (5% [corrected] in control participants; adjusted odds ratio, 6.11 [95% CI, 1.65-22.6]) while collectively, other respiratory viruses were not associated with severe disease (23% in control participants; adjusted odds ratio, 1.27 [95% CI, 0.64-2.52]).

CONCLUSION

In a sample of Kenyan infants and children admitted with severe pneumonia to a rural hospital, RSV was the predominant viral pathogen.

Changing epidemiology of bacterial meningitis

Immunization against the most common meningeal pathogens is the leading factor associated with decreased incidence of bacterial meningitis in countries where routine vaccination is available. This is most dramatically illustrated by the reduction in the incidence of Haemophilus influenzae type b meningitis. The incidence of bacterial meningitis has decreased by 55% since the introduction of the H. influenzae type b conjugate vaccine in 1990. H. influenzae occurred primarily in children younger than 5 years of age, and so the median age of patients with bacterial meningitis has now increased to 39 years of age in the United States, and the leading pathogen is currently Streptococcus pneumoniae. Three other control measures (ie, universal screening and antibiotic prophylaxis of pregnant women for Group B streptococci and the implementation and availability of the S. pneumoniae and Neisseria meningitidis conjugate vaccines) have likely further decreased the incidence of these meningeal pathogens. Lastly, the worldwide emergence of multidrug-resistant pneumococci has complicated the empiric therapy of bacterial meningitis.

Bacterial meningitis: epidemiology, pathogenesis and management update

Bacterial meningitis continues to be an important disease throughout the world and can be a life-threatening emergency if not suspected, appropriately diagnosed and managed expeditiously. The epidemiology of bacterial meningitis has changed dramatically over the last 20 years, primarily as a result of the introduction of conjugate vaccines against the common meningeal pathogens, such that in the developed world where vaccination is routinely utilized, bacterial meningitis has become a disease of adults rather than of infants and children. The management approach to patients with suspected or proven bacterial meningitis includes emergent cerebrospinal fluid analysis and initiation of appropriate antimicrobial and adjunctive therapies. The choice of empirical antimicrobial therapy is based on the patient's age and underlying disease status; once the infecting pathogen is isolated, antimicrobial therapy can be modified for optimal treatment. Many patients with suspected or proven bacterial meningitis should also receive adjunctive dexamethasone therapy. This is based on experimental animal model data which demonstrated that the subarachnoid space inflammatory response that results from antimicrobial-induced bacterial lysis can contribute to morbidity and mortality. Clinical studies have demonstrated the benefit of adjunctive dexamethasone in infants and children with Haemophilus influenzae type B meningitis, and adults with pneumococcal meningitis, in which mortality and adverse outcome are reduced. Use of adjunctive dexamethasone in adults with meningitis caused by other bacteria, and in infants and children with pneumococcal meningitis, is controversial. To be effective, adjunctive dexamethasone should be administered concomitant with or just prior to the first antimicrobial dose for maximal effect on the subarachnoid space inflammatory response.