RESUMEN
An emm-cluster based system was proposed as a standard typing scheme to facilitate and enhance future studies of group A Streptococcus (GAS) epidemiological surveillance, M protein function, and vaccine development strategies. We provide an evidence-based distribution of GAS emm clusters in Africa and assess the potential coverage of the new 30-valent vaccine in terms of an emm cluster-based approach. Two reviewers independently assessed studies retrieved from a comprehensive search and extracted relevant data. Meta-analyses were performed (random-effects model) to aggregate emm cluster prevalence estimates. Eight studies (n = 1,595 isolates) revealed the predominant emm clusters as E6 (18%; 95% confidence interval [CI], 12.6% to 24.0%), followed by E3 (14%; 95% CI, 11.2% to 17.4%) and E4 (13%; 95% CI, 9.5% to 16.0%). There was negligible variation in emm clusters with regard to regions, age, and socioeconomic status across the continent. Considering an emm cluster-based vaccine strategy, which assumes cross-protection within clusters, the 30-valent vaccine currently in clinical development would provide hypothetical coverage to 80.3% of isolates in Africa. This systematic review indicates the most predominant GAS emm cluster in Africa is E6 followed by E3, E4, and D4. The current 30-valent vaccine would provide considerable coverage across the diversity of emm cluster types in Africa. Future efforts could be directed toward estimating the overall potential coverage of the new 30-valent vaccine based on cross-opsonization studies with representative panels of GAS isolates from populations at highest risk for GAS diseases.IMPORTANCE Low vaccine coverage is of grave public health concern, particularly in developing countries where epidemiological data are often absent. To inform vaccine development for group A Streptococcus (GAS), we report on the epidemiology of the M protein emm clusters from GAS infections in Africa, where GAS-related illnesses and their sequelae, including rheumatic fever and rheumatic heart disease, are of a high burden. This first report of emm clusters across the continent indicates a high probably of coverage by the M protein-based vaccine currently undergoing testing were an emm-cluster based approach to be used.
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Antígenos Bacterianos/genética , Proteínas de la Membrana Bacteriana Externa/genética , Proteínas Portadoras/genética , Infecciones Estreptocócicas/epidemiología , Infecciones Estreptocócicas/prevención & control , Vacunas Estreptocócicas/química , Streptococcus pyogenes/clasificación , África/epidemiología , Antígenos Bacterianos/química , Humanos , Prevalencia , Infecciones Estreptocócicas/microbiologíaRESUMEN
BACKGROUND: The prevalence of group A streptococcal (GAS) disease is estimated at >18.1 million cases with an incidence of >1.78 million cases per year. While a significant cause of mortality and morbidity on the global scale, the burden of GAS disease in Africa is unknown. We conducted a systematic review on the prevalence of GAS disease among children and adults in Africa and the frequency and distribution of emm types among isolates. METHODS: We performed a comprehensive literature search in a number of databases, using an African search filter. Two reviewers independently selected articles meeting pre-specified criteria and extracted relevant data as per a data extraction form. We applied the random-effects meta-analysis model to aggregate GAS prevalence estimates with 95% CI for GAS prevalence, incorporating the Freeman-Tukey transformation to account for between-study variability. RESULTS: Twenty-five studies were included. Invasive GAS disease prevalence ranged from 0.6% to 10.8% in samples from normally-sterile sites including blood, CSF and soft tissue. A single study reported a prevalence of 74% in skin infections. Prevalence of emm types varied with up to 88 different strains reported, corresponding to a vaccine coverage of 28% to 65%. The pooled prevalence of GAS in persons presenting with pharyngitis was 21% (95% CI, 17% to 26%). CONCLUSIONS: The prevalence of GAS remains high among symptomatic individuals residing in Africa. Data on molecular strain characterisation of GAS in Africa is largely non-existent, thus the need for further studies is warranted to inform current prevention efforts including vaccine development.
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Cardiopatía Reumática , Infecciones Estreptocócicas , Vacunas , Adulto , África/epidemiología , Niño , Humanos , Prevalencia , Cardiopatía Reumática/diagnóstico , Cardiopatía Reumática/epidemiología , Cardiopatía Reumática/prevención & control , Infecciones Estreptocócicas/epidemiología , Infecciones Estreptocócicas/prevención & control , Streptococcus pyogenesRESUMEN
BACKGROUND: Rheumatic heart disease (RHD) is an important and preventable cause of cardiovascular disease. OBJECTIVES: As part of a recent RHD initiative in Uganda and Tanzania, we systematically reviewed group A streptococcal disease (GAS), acute rheumatic fever (ARF), and RHD in these countries. METHODS: Using a systematic review and meta-analysis/meta-synthesis, we searched PubMed, Embase, and grey literature for quantitative and qualitative studies conducted in Uganda and Tanzania that included individuals affected by GAS, ARF, and RHD. We pre-specified 3 sets of outcomes: 1) disease epidemiology; 2) barriers and facilitators to health care; and 3) stakeholder identification and engagement. Study descriptors, outcomes, and interest, and quality assessments were recorded. For the first objective, we conducted random-effects meta-analyses. For the second objective, we produced a narrative synthesis of themes. No studies contained data on the third objective. RESULTS: Of 293 records identified, 12 met our inclusion criteria (9 for objective 1 and 3 for objective 2). Most quantitative studies were at moderate or high risk of bias, and only 1 of 2 qualitative studies was high quality. We estimated the prevalence of RHD to be 17.9 (95% confidence interval [CI]: 4.0 to 41.2) per 1,000 individuals. The most frequent nonfatal sequelae were heart failure, pulmonary hypertension, and atrial fibrillation. Case-fatality rates in medical and surgical wards were 17% (95% CI: 13% to 21%) and 27% (95% CI: 18% to 36%), respectively. Barriers and facilitators to GAS and RHD care were identified in the domains of individual knowledge, family support, provider communication and knowledge, and system design. CONCLUSIONS: RHD remains endemic in Tanzania and Uganda, and symptomatic RHD is associated with high rates of morbidity and mortality. We have identified critical data gaps in the areas of GAS and ARF epidemiology as well as health care utilization patterns and their determinants.
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Fiebre Reumática/epidemiología , Cardiopatía Reumática/epidemiología , Infecciones Estreptocócicas/epidemiología , Adolescente , Adulto , Niño , Preescolar , Femenino , Humanos , Masculino , Persona de Mediana Edad , Prevalencia , Tanzanía/epidemiología , Uganda/epidemiología , Adulto JovenRESUMEN
INTRODUCTION: Rheumatic heart disease (RHD) is a chronic disease affecting the heart valves, secondary to group A streptococcal infection (GAS) and subsequent acute rheumatic fever (ARF). However, RHD cure and preventative measures are inextricably linked with socioeconomic development, as the disease mainly affects children and young adults living in poverty. In order to address RHD, public health officials and health policymakers require up-to-date knowledge on the epidemiology of GAS, ARF and RHD, as well as the existing enablers and gaps in delivery of evidence-based care for these conditions. We propose to conduct a systematic review to assess the literature comprehensively, synthesising all existing quantitative and qualitative data relating to RHD in Africa. METHODS AND ANALYSIS: We plan to conduct a comprehensive literature search using a number of databases and reference lists of relevant articles published from January 1995 to December 2015. Two evaluators will independently review and extract data from each article. Additionally, we will assess overall study quality and risk of bias, using the Newcastle-Ottawa Scale and the Critical Appraisal Skills Programme criteria for quantitative and qualitative studies, respectively. We will meta-analyse estimates of prevalence, incidence, case fatality and mortality for each of the conditions separately for each country. Qualitative meta-analysis will be conducted for facilitators and barriers in RHD health access. Lastly, we will create a list of key stakeholders. This protocol is registered in the PROSPERO International Prospective Register of systematic reviews, registration number CRD42016032852. ETHICS AND DISSEMINATION: The information provided by this review will inform and assist relevant stakeholders in identifying key areas of intervention, and designing and implementing evidence-based programmes and policies at the local and regional level. With slight modifications (ie, to the country terms in the search strategy), this protocol can be used as part of a needs assessment in any endemic country.