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BACKGROUND: Scabies is a common parasitic skin condition that causes considerable morbidity globally. Clinical and epidemiological research for scabies has been limited by a lack of standardization of diagnostic methods. OBJECTIVES: To develop consensus criteria for the diagnosis of common scabies that could be implemented in a variety of settings. METHODS: Consensus diagnostic criteria were developed through a Delphi study with international experts. Detailed recommendations were collected from the expert panel to define the criteria features and guide their implementation. These comments were then combined with a comprehensive review of the available literature and the opinion of an expanded group of international experts to develop detailed, evidence-based definitions and diagnostic methods. RESULTS: The 2020 International Alliance for the Control of Scabies (IACS) Consensus Criteria for the Diagnosis of Scabies include three levels of diagnostic certainty and eight subcategories. Confirmed scabies (level A) requires direct visualization of the mite or its products. Clinical scabies (level B) and suspected scabies (level C) rely on clinical assessment of signs and symptoms. Evidence-based, consensus methods for microscopy, visualization and clinical symptoms and signs were developed, along with a media library. CONCLUSIONS: The 2020 IACS Criteria represent a pragmatic yet robust set of diagnostic features and methods. The criteria may be implemented in a range of research, public health and clinical settings by selecting the appropriate diagnostic levels and subcategories. These criteria may provide greater consistency and standardization for scabies diagnosis. Validation studies, development of training materials and development of survey methods are now required. What is already known about this topic? The diagnosis of scabies is limited by the lack of accurate, objective tests. Microscopy of skin scrapings can confirm the diagnosis, but it is insensitive, invasive and often impractical. Diagnosis usually relies on clinical assessment, although visualization using dermoscopy is becoming increasingly common. These diagnostic methods have not been standardized, hampering the interpretation of findings from clinical research and epidemiological surveys, and the development of scabies control strategies. What does this study add? International consensus diagnostic criteria for common scabies were developed through a Delphi study with global experts. The 2020 International Alliance for the Control of Scabies (IACS) Criteria categorize diagnosis at three levels of diagnostic certainty (confirmed, clinical and suspected scabies) and eight subcategories, and can be adapted to a range of research and public health settings. Detailed definitions and figures are included to aid training and implementation. The 2020 IACS Criteria may facilitate the standardization of scabies diagnosis.
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Escabiosis , Administración Tópica , Consenso , Humanos , Escabiosis/diagnóstico , Escabiosis/epidemiología , PielRESUMEN
Infections with Sarcoptes scabiei, or scabies, remain common in many disadvantaged populations. Mass drug administration (MDA) has been used in such settings to achieve a rapid reduction in infection and transmission, with the goal of eliminating the public health burden of scabies. While prevalence has been observed to fall substantially following such an intervention, in some instances resurgence of infection to baseline levels has occurred over several years. To explore the biology underpinning this phenomenon, we have developed a theoretical model of scabies life-cycle and transmission dynamics in a homogeneously mixing population, and simulate the impact of mass drug treatment strategies acting on egg and mite life cycle stages (ovicidal) or mites alone (non-ovicidal). In order to investigate the dynamics of the system, we first define and calculate the optimal interval between treatment doses. We calculate the probability of eradication as a function of the number of optimally-timed successive treatment doses and the number of years over which a program is run. For the non-ovicidal intervention, we first show that at least two optimally-timed doses are required to achieve eradication. We then demonstrate that while more doses over a small number of years provides the highest chance of eradication, a similar outcome can be achieved with fewer doses delivered annually over a longer period of time. For the ovicidal intervention, we find that doses should be delivered as close together as possible. This work provides a platform for further research into optimal treatment strategies which may incorporate heterogeneity of transmission, and the interplay between MDA and enhancement of continuing scabies surveillance and treatment strategies.
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Antiparasitarios/administración & dosificación , Modelos Biológicos , Sarcoptes scabiei , Escabiosis , Animales , Humanos , Sarcoptes scabiei/efectos de los fármacos , Sarcoptes scabiei/patogenicidad , Escabiosis/tratamiento farmacológico , Escabiosis/prevención & control , Escabiosis/transmisiónRESUMEN
Human scabies (infestation with the mite Sarcoptes scabiei var hominis) causes a significant disease burden worldwide, yet there are no agreed diagnostic guidelines. We aimed to determine whether a consistent approach to diagnosing scabies has been used for published scabies therapeutic trials. The data sources used were the MEDLINE, Embase and Cochrane databases, from 1946 to 29 August 2013. Eligible studies were trials of therapeutic interventions against scabies in human subjects, published in English, enrolling patients with scabies, and using various therapeutic interventions. Language was a limitation of this study as some relevant trials published in languages other than English may have been excluded. Each study was reviewed by two independent authors, who assessed the clinical examination and testing approaches used for scabies diagnosis in the included studies. We found that of 71 included trials, 40 (56%) specified which clinical findings were used for diagnosis, which were predominantly rash, rash distribution, pruritus and mite burrows. Parasitological testing was used in 63% of trials (n = 45) and was used more frequently in clinic-based than in field studies. Nearly one-quarter of trials (24%, n = 17) did not define the diagnostic method used. Overall, the diagnostic approaches were poorly described, prohibiting accurate comparison of existing studies. This review further supports the need for consensus diagnostic guidelines for scabies.
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Escabiosis/diagnóstico , Ensayos Clínicos como Asunto , Diagnóstico Diferencial , Humanos , Escabiosis/terapiaRESUMEN
BACKGROUND: The practice of counting bacterial colony forming units on agar plates has long been used as a method to estimate the concentration of live bacteria in culture. However, due to the laborious and potentially error prone nature of this measurement technique, an alternative method is desirable. Recent technologic advancements have facilitated the development of automated colony counting systems, which reduce errors introduced during the manual counting process and recording of information. An additional benefit is the significant reduction in time taken to analyse colony counting data. Whilst automated counting procedures have been validated for a number of microorganisms, the process has not been successful for all bacteria due to the requirement for a relatively high contrast between bacterial colonies and growth medium. The purpose of this study was to validate an automated counting system for use with group A Streptococcus (GAS). METHODS: Twenty-one different GAS strains, representative of major emm-types, were selected for assessment. In order to introduce the required contrast for automated counting, 2,3,5-triphenyl-2H-tetrazolium chloride (TTC) dye was added to Todd-Hewitt broth with yeast extract (THY) agar. Growth on THY agar with TTC was compared with growth on blood agar and THY agar to ensure the dye was not detrimental to bacterial growth. Automated colony counts using a ProtoCOL 3 instrument were compared with manual counting to confirm accuracy over the stages of the growth cycle (latent, mid-log and stationary phases) and in a number of different assays. The average percentage differences between plating and counting methods were analysed using the Bland-Altman method. RESULTS: A percentage difference of ±10 % was determined as the cut-off for a critical difference between plating and counting methods. All strains measured had an average difference of less than 10 % when plated on THY agar with TTC. This consistency was also observed over all phases of the growth cycle and when plated in blood following bactericidal assays. Agreement between these methods suggest the use of an automated colony counting technique for GAS will significantly reduce time spent counting bacteria to enable a more efficient and accurate measurement of bacteria concentration in culture.
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Recuento de Colonia Microbiana/métodos , Streptococcus pyogenes/aislamiento & purificación , Automatización , Bioensayo , Humanos , Reproducibilidad de los Resultados , Streptococcus pyogenes/crecimiento & desarrollo , TemperaturaRESUMEN
Epidemiological data regarding group A streptococcal (GAS) infections in South East Asia are scarce with no information from Laos. We characterized emm types, emm clusters and the antibiotic resistance profile of 124 GAS isolates recovered in Laos during 2004-2013. Most strains were recovered from skin and invasive infections (76% and 19%, respectively). Thirty-four emm types were identified as belonging to 12 emm clusters and no novel emm types were identified. No significant differences were observed in the distribution of emm types or emm clusters according to age or site of recovery (skin or invasive infections). There was moderate strain diversity in this country but considerable differences in emm-type distribution between Laos, Thailand and Cambodia. Vaccine coverage was high for the J8 vaccine candidate. The theoretical coverage for the 30-valent vaccine candidate needs further investigation. Antibiotic resistance was moderate to erythromycin and chloramphenicol (8% and 7%, respectively) and low to ofloxacin (<1%).
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Infecciones Estreptocócicas/epidemiología , Infecciones Estreptocócicas/microbiología , Streptococcus pyogenes/clasificación , Streptococcus pyogenes/aislamiento & purificación , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Antibacterianos/farmacología , Antígenos Bacterianos/genética , Proteínas de la Membrana Bacteriana Externa/genética , Proteínas Portadoras/genética , Niño , Preescolar , Análisis por Conglomerados , Farmacorresistencia Bacteriana , Femenino , Variación Genética , Genotipo , Humanos , Lactante , Recién Nacido , Laos/epidemiología , Masculino , Pruebas de Sensibilidad Microbiana , Persona de Mediana Edad , Epidemiología Molecular , Infecciones Estreptocócicas/prevención & control , Vacunas Estreptocócicas/administración & dosificación , Streptococcus pyogenes/genética , Vacunación/estadística & datos numéricos , Adulto JovenRESUMEN
BACKGROUND: Improving outcomes beyond survival for high-risk newborns in resource-limited settings is an emerging challenge. Global estimates demonstrate the scale of this challenge and significant gaps in morbidity outcome data in high mortality contexts. A systematic review was conducted to document the prevalence of neurodevelopmental impairment in high-risk newborns who were followed up into childhood in low- and middle-income countries. METHODS: High-risk newborns were defined as low, very or extremely low birthweight, preterm infants or those surviving birth asphyxia or serious infections. Electronic databases were searched and articles screened for eligibility. Included articles were appraised according to STROBE criteria. Narrative review was performed and median prevalence of key neurodevelopmental outcomes was calculated where data quality allowed. RESULTS: 6959 articles were identified with sixty included in final review. At follow-up in early childhood, median estimated prevalence (inter-quartile range) of overall neurodevelopmental impairment, cognitive impairment and cerebral palsy were: for survivors of prematurity/very low birthweight 21.4% (11.6-30.8), 16.3% (6.3-29.6) and 11.2% (5.9-16.1), respectively, and for survivors of birth asphyxia 34.6% (25.4-51.5), 11.3% (7.7-11.8) and 22.8% (15.7-31.4), respectively. Only three studies reporting outcomes following newborn serious bacterial infections were identified. There was limited reporting of important outcomes such as vision and hearing impairment. Major challenges with standardised reporting of key exposure and developmental outcome variables and lack of control data were identified. CONCLUSION: Understanding the limitations of the available data on neurodevelopmental outcome in newborns in resource-limited settings provides clear direction for research and efforts to improve long-term outcome in high-risk newborns in these settings.
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Asfixia Neonatal/complicaciones , Enfermedades Transmisibles/congénito , Recién Nacido de Bajo Peso , Recien Nacido Prematuro , Trastornos del Neurodesarrollo/epidemiología , Países en Desarrollo , Estudios de Seguimiento , Humanos , Recién NacidoRESUMEN
Clinicians frequently request serologic tests to provide evidence of prior infection by Streptococcus pyogenes, especially when suspecting a diagnosis of acute rheumatic fever or post-streptococcal glomerulonephritis. However, the interpretation of these tests is difficult and should take account of the clinical features, epidemiological setting, and pre-test probability, as well as the specific aspects of the assay. This review details the characteristics of streptococcal serologic assays and provides recommendations for their use and interpretation.
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Anticuerpos Antibacterianos/sangre , Glomerulonefritis/diagnóstico , Fiebre Reumática/diagnóstico , Pruebas Serológicas/métodos , Infecciones Estreptocócicas/diagnóstico , Streptococcus pyogenes/inmunología , Humanos , Infecciones Estreptocócicas/complicacionesRESUMEN
OBJECTIVE: To estimate the echocardiography confirmed prevalence of rheumatic heart disease (RHD) in school children in Fiji. DESIGN: Cross-sectional observational study. SETTING: Ten primary schools in Fiji. PATIENTS: School children aged 5-14 years. INTERVENTIONS: Each child had an echocardiogram performed by an echocardiographic technician subsequently read by a paediatric cardiologist not involved with field screening, and auscultation performed by a paediatrician. MAIN OUTCOME MEASURES: Echocardiographic criteria for RHD diagnosis were based on those previously published by the National Institutes of Health (NIH) and World Health Organization (WHO), and data were also analyzed using the new World Heart Federation (WHF) criteria. Prevalence figures were calculated with binomial 95% confidence intervals. RESULTS: Using the modified NIH/WHO criteria the prevalence of definite RHD prevalence was 7.2 cases per 1000 (95% CI 3.7-12.5), and the prevalence of probable RHD 28.2 cases per 1000 (95% CI 20.8-37.3). By applying the WHF criteria the prevalence of definite and borderline RHD was 8.4 cases per 1000 (95% CI 4.6-14.1) and 10.8 cases per 1000 (95% CI 6.4-17.0) respectively. Definite RHD was more common in females (OR 5.1, 95% CI 1.1-48.3) and in children who attended school in a rural location (OR 2.3, 95% CI 0.6-13.50). Auscultation was poorly sensitive compared to echocardiography (30%). CONCLUSION: There is a high burden of undiagnosed RHD in Fiji. Auscultation is poorly sensitive when compared to echocardiography in the detection of asymptomatic RHD. The results of this study highlight the importance of the use of highly sensitive and specific diagnostic criteria for echocardiography diagnosis of RHD.
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Ecocardiografía/estadística & datos numéricos , Tamizaje Masivo/estadística & datos numéricos , Cardiopatía Reumática/diagnóstico por imagen , Cardiopatía Reumática/epidemiología , Adolescente , Niño , Preescolar , Estudios Transversales , Países en Desarrollo/estadística & datos numéricos , Femenino , Fiji/epidemiología , Auscultación Cardíaca/estadística & datos numéricos , Humanos , Masculino , Prevalencia , Asignación de Recursos/estadística & datos numéricos , Instituciones Académicas , Sensibilidad y Especificidad , Organización Mundial de la SaludRESUMEN
Group A Streptococcus (GAS) M protein is an important virulence factor and potential vaccine antigen, and constitutes the basis for strain typing (emm-typing). Although >200 emm-types are characterized, structural data were obtained from only a limited number of emm-types. We aim to evaluate the sequence diversity of near-full-length M proteins from worldwide sources and analyse their structure, sequence conservation and classification. GAS isolates recovered from throughout the world during the last two decades underwent emm-typing and complete emm gene sequencing. Predicted amino acid sequence analyses, secondary structure predictions and vaccine epitope mapping were performed using MUSCLE and Geneious software. A total of 1086 isolates from 31 countries were analysed, representing 175 emm-types. emm-type is predictive of the whole protein structure, independent of geographical origin or clinical association. Findings of an emm-type paired with multiple, highly divergent central regions were not observed. M protein sequence length, the presence or absence of sequence repeats and predicted secondary structure were assessed in the context of the latest vaccine developments. Based on these global data, the M6 protein model is updated to a three representative M protein (M5, M80 and M77) model, to aid in epidemiological analysis, vaccine development and M protein-related pathogenesis studies.
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Antígenos Bacterianos/química , Antígenos Bacterianos/genética , Proteínas de la Membrana Bacteriana Externa/química , Proteínas de la Membrana Bacteriana Externa/genética , Proteínas Portadoras/química , Proteínas Portadoras/genética , Streptococcus pyogenes/química , Streptococcus pyogenes/genética , Antígenos Bacterianos/inmunología , Proteínas de la Membrana Bacteriana Externa/inmunología , Proteínas Portadoras/inmunología , ADN Bacteriano/química , ADN Bacteriano/genética , Mapeo Epitopo , Epítopos/genética , Epítopos/inmunología , Variación Genética , Salud Global , Humanos , Modelos Moleculares , Datos de Secuencia Molecular , Conformación Proteica , Análisis de Secuencia de ADN , Infecciones Estreptocócicas/microbiología , Streptococcus pyogenes/inmunología , Streptococcus pyogenes/aislamiento & purificaciónRESUMEN
Scabies remains one of the commonest of skin diseases seen in developing countries. Although its distribution is subject to a cycle of infection, with peaks and troughs of disease prevalence, this periodicity is often less obvious in poor communities. Scabies is a condition that affects families, particularly the most vulnerable; it also has the greatest impact on young children. Largely through the association with secondary bacterial infection caused by group A streptococci and Staphylococcus aureus, the burden of disease is compounded by nephritis, rheumatic fever and sepsis in developing countries. However, with a few notable exceptions, it remains largely neglected as an important public health problem. The purpose of this review is to provide an update on the current position of scabies with regard to its complications and control in resource-poor countries.
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Países en Desarrollo , Manejo de la Enfermedad , Sarcoptes scabiei/patogenicidad , Escabiosis/complicaciones , Escabiosis/epidemiología , Animales , Coinfección/tratamiento farmacológico , Coinfección/epidemiología , Coinfección/microbiología , Coinfección/parasitología , Control de Enfermedades Transmisibles/métodos , Transmisión de Enfermedad Infecciosa/prevención & control , Humanos , Ivermectina/administración & dosificación , Ivermectina/uso terapéutico , Prevalencia , Ensayos Clínicos Controlados Aleatorios como Asunto , Escabiosis/tratamiento farmacológico , Escabiosis/parasitología , Infecciones Estreptocócicas/complicaciones , Infecciones Estreptocócicas/tratamiento farmacológico , Infecciones Estreptocócicas/epidemiología , Infecciones Estreptocócicas/microbiología , Streptococcus/patogenicidadRESUMEN
We undertook a 5-year retrospective study of group A streptococcal (GAS) bacteraemia in Fiji, supplemented by a 9-month detailed retrospective study of beta-haemolytic streptococcal (BHS) infections. The all-age incidence of GAS bacteraemia over 5 years was 11.6/100,000. Indigenous Fijians were 4.7 times more likely to present with invasive BHS disease than people of other ethnicities, and 6.4 times more likely than Indo-Fijians. The case-fatality rate for invasive BHS infections was 28%. emm-typing was performed on 23 isolates: 17 different emm-types were found, and the emm-type profile was different from that found in industrialized nations. These data support the contentions that elevated rates of invasive BHS and GAS infections are widespread in developing countries, and that the profile of invasive organisms in these settings reflects a wide diversity of emm-types and a paucity of types typically found in industrialized countries.
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Bacteriemia/epidemiología , Bacteriemia/microbiología , Infecciones Estreptocócicas/epidemiología , Infecciones Estreptocócicas/microbiología , Streptococcus pyogenes/aislamiento & purificación , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Antígenos Bacterianos/genética , Bacteriemia/mortalidad , Proteínas de la Membrana Bacteriana Externa/genética , Técnicas de Tipificación Bacteriana , Proteínas Portadoras/genética , Niño , Preescolar , ADN Bacteriano , Etnicidad , Femenino , Fiji/epidemiología , Genotipo , Humanos , Incidencia , Lactante , Recién Nacido , Masculino , Persona de Mediana Edad , Estudios Retrospectivos , Infecciones Estreptocócicas/mortalidadRESUMEN
OBJECTIVES: To consider the worldwide prevalence of rheumatic heart disease in children in developing countries using surveys with uniform methodologies, and to consider the effect of environmental factors including socio-economic status, overcrowding, urbanization, nutrition and access to medical services on the distribution of rheumatic heart disease in developing countries. METHODS: Sixty-one surveys of the prevalence of rheumatic heart disease in developing countries were found using a systematic review of MEDLINE from January 1976 to July 1999. Twenty-four studies were selected for comparison based on their uniform methodological and diagnostic techniques. RESULTS: There is a high prevalence of rheumatic heart disease in the Pacific region with a lower prevalence in the Indian subcontinent, Asian, sub-Saharan African, Mediterranean, Latin American and Caribbean regions. However, aside from the Indian subcontinent, these regions have not been well studied, and it may be that the true prevalence is actually higher. CONCLUSIONS: There is a lack of good quality prevalence surveys of rheumatic heart disease in developing countries. It appears that a threshold level where higher socio-economic status is associated with reduced prevalence of rheumatic heart disease is not reached in developing countries. Therefore, differences in prevalence between socio-economic groups in the one area cannot be detected. A similar case can be made for overcrowding. Many regions need well-designed studies of rheumatic heart disease that incorporate assessment of environmental factors as well as the study of the microbiological epidemiology of rheumatic heart disease and group A streptococci.