Systematic review of household transmission of Strep A: A potential site for prevention that has eluded attention.

BACKGROUND: Despite being the sixth most common infectious disease globally, transmission of Streptococcus pyogenes (Strep A) within the household remains an understudied driver of infection. We undertook a systematic review to better understand the transmission of Strep A between people within the home while highlighting opportunities for prevention. METHODS: A search strategy was applied to five databases between September 2022 and March 2023. Results were limited to those published between January 2000 and March 2023. Texts were reviewed by two authors and the following data extracted: article details (title, author, year), study type, transmission year, country, participant age/s, infection status, molecular testing, and transmission mode. Funding was provided by the Australian National Health and Medical Research Council (NHMRC, grant number GNT2010716). RESULTS: The final analysis comprised 28 texts. Only seven studies (25.0%) provided sufficient detail to identify the Strep A transmission mode. These were contact (4), vehicle (bedding; clothing; other fabric, and medical equipment, [2]), and contact with animals (1). All others were classified as household (specific mode unascertainable). Most articles reported outbreaks involving invasive Strep A infections. CONCLUSIONS: There is limited literature regarding household transmission of Strep A. Understanding transmission in this setting remains imperative to guide control methods.

The burden of atopic dermatitis and bacterial skin infections among urban-living Indigenous children and young people in high-income countries: A systematic review.

BACKGROUND: A high burden of bacterial skin infections (BSI) is well documented in remote-living Indigenous children and young people (CYP) in high-income countries (HIC). Atopic dermatitis (AD) is the most common chronic inflammatory skin condition seen in CYP and predisposes to BSI. Despite the rate of urbanization for Indigenous people increasing globally, research is lacking on the burden of AD and BSI for urban-living Indigenous CYP in HIC. Indigenous people in HIC share a history of colonization, displacement and subsequent ongoing negative impacts on health. OBJECTIVE: To provide a global background on the burden of AD and BSI in urban-living Indigenous CYP in HIC. METHODS: A systematic review of primary observational studies on AD and BSI in English containing epidemiologic data was performed. MEDLINE, EMBASE, EMCARE, Web of Science, and PubMed databases were searched for articles between January 1990 and December 2021. RESULTS: From 2278 original manuscripts, 16 were included: seven manuscripts documenting eight studies on AD; and nine manuscripts documenting nine studies on BSI. Current and severe symptoms of AD were more common in urban-living Indigenous CYP in HIC compared with their non-Indigenous peers, with children having a higher prevalence than adolescents. Urban-living Indigenous CYP in HIC had a higher incidence of all measures of BSI compared with their non-Indigenous peers, and were over-represented for all measures of BSI compared with their proportion of the background population. Limitations include incomplete representation of all Indigenous populations in HIC. CONCLUSION: A significant burden of AD and BSI exists in urban-living Indigenous CYP in HIC.

Pediatric Staphylococcus aureus Bacteremia: Clinical Spectrum and Predictors of Poor Outcome.

BACKGROUND: Staphylococcus aureus is a common cause of bacteremia, yet the epidemiology and predictors of poor outcome remain inadequately defined in childhood. METHODS: ISAIAH (Invasive Staphylococcus aureus Infections and Hospitalizations in children) is a prospective, cross-sectional study of S. aureus bacteremia (SAB) in children hospitalized in Australia and New Zealand over 24 months (2017-2018). RESULTS: Overall, 552 SABs were identified (incidence 4.4/100 000/year). Indigenous children, those from lower socioeconomic areas and neonates were overrepresented. Although 90-day mortality was infrequent, one-third experienced the composite of: length of stay >30 days (26%), intensive care unit admission (20%), relapse (4%), or death (3%). Predictors of mortality included prematurity (adjusted odds ratio [aOR],16.8; 95% confidence interval [CI], 1.6-296.9), multifocal infection (aOR, 22.6; CI, 1.4-498.5), necrotizing pneumonia (aOR, 38.9; CI, 1.7-1754.6), multiorgan dysfunction (aOR, 26.5; CI, 4.1-268.8), and empiric vancomycin (aOR, 15.7; CI, 1.6-434.4); while infectious diseases (ID) consultation (aOR, 0.07; CI .004-.9) was protective. Neither MRSA nor vancomycin trough targets impacted survival; however, empiric vancomycin was associated with nephrotoxicity (OR, 3.1; 95% CI 1.3-8.1). CONCLUSIONS: High SAB incidence was demonstrated and for the first time in a pediatric setting, necrotizing pneumonia and multifocal infection were predictors of mortality, while ID consultation was protective. The need to reevaluate pediatric vancomycin trough targets and limit unnecessary empiric vancomycin exposure to reduce poor outcomes and nephrotoxicity is highlighted. One in 3 children experienced considerable SAB morbidity; therefore, pediatric inclusion in future SAB comparator trials is paramount to improve outcomes.

Penicillin G concentrations required for prophylaxis against Group A Streptococcus infection evaluated using a hollow fibre model and mathematical modelling.

BACKGROUND: Acute rheumatic fever (ARF), an autoimmune reaction to Group A Streptococcus (Streptococcus pyogenes; Strep A) infection, can cause rheumatic heart disease (RHD). New formulations of long-acting penicillins are being developed for secondary prophylaxis of ARF and RHD. OBJECTIVES: To evaluate the penicillin G concentrations required to suppress growth of Strep A. METHODS: Broth microdilution MIC and MBC for Strep A strains M75611024, M1T15448 and M18MGAS8232 were determined. All strains were studied in a hollow fibre model (initial inoculum 4 log10 cfu/mL). Constant penicillin G concentrations of 0.008, 0.016 and 0.05 mg/L were examined against all strains, plus 0.012 mg/L against M18MGAS8232. Viable counts were determined over 144 h. Subsequently, all penicillin G-treated cartridges were emptied, reinoculated with 5 log10 cfu/mL and counts determined over a further 144 h. Mathematical modelling was performed. RESULTS: MIC and MBC were 0.008 mg/L for all strains; small subpopulations of M75611024 and M1T15448, but not M18MGAS8232, grew at 1× MIC. Following the first inoculation, 0.008 mg/L achieved limited killing and/or stasis against M75611024 and M1T15448, with subsequent growth to ∼6 log10 cfu/mL. Following both inocula, concentrations ≥0.016 mg/L suppressed M75611024 and M1T15448 to <1 log10 cfu/mL from 6 h onwards with eradication. Concentrations ≥0.008 mg/L suppressed M18MGAS8232 to <1 log10 cfu/mL from 24 h onwards with eradication after both inoculations. Mathematical modelling well described all strains using a single set of parameter estimates, except for different maximum bacterial concentrations and proportions of bacteria growing at 1× MIC. CONCLUSIONS: In the absence of validated animal and human challenge models, the study provides guidance on penicillin G target concentrations for development of new penicillin formulations.

The Spectrum, Severity and Outcomes of Rheumatic Mitral Valve Disease in Pregnant Women in Australia and New Zealand.

BACKGROUND: Rheumatic heart disease (RHD) poses significant perinatal risks. We aimed to describe the spectrum, severity and outcomes of rheumatic mitral valve disease in pregnancy in Australia and New Zealand. METHODS: A prospective, population-based cohort study of pregnant women with RHD recruited 2013-14 through the hospital-based Australasian Maternity Outcomes Surveillance System. Outcome measures included maternal and perinatal morbidity and mortality. Univariable and multivariable logistic regression analyses were undertaken to test for predictors of adverse maternal and perinatal outcomes. RESULTS: Of 274 pregnant women identified with RHD, 124 (45.3%) had mitral stenosis (MS) and 150 (54.7%) had isolated mitral regurgitation (MR). One woman with mild MS/moderate MR died. There were six (2.2%) stillbirths and two (0.7%) neonatal deaths. Babies born to women with MS were twice as likely to be small-for-gestational-age (22.7% vs 11.4%, p=0.013). In women with MS, use of cardiac medication (AOR 7.42) and having severe stenosis (AOR 16.35) were independently associated with adverse cardiac outcomes, while New York Heart Association (NYHA) class >1 (AOR 3.94) was an independent predictor of adverse perinatal events. In women with isolated MR, use of cardiac medications (AOR 7.03) and use of anticoagulants (AOR 6.05) were independently associated with adverse cardiac outcomes. CONCLUSIONS: Careful monitoring and specialist care for women with RHD in pregnancy is required, particularly for women with severe MS, those on cardiac medication, and those on anticoagulation, as these are associated with increased risk of adverse maternal cardiac outcomes. In the context of pregnancy, contraception and preconception planning are important for young women diagnosed with RHD.

Estimation of the force of infection and infectious period of skin sores in remote Australian communities using interval-censored data.

Prevalence of impetigo (skin sores) remains high in remote Australian Aboriginal communities, Fiji, and other areas of socio-economic disadvantage. Skin sore infections, driven primarily in these settings by Group A Streptococcus (GAS) contribute substantially to the disease burden in these areas. Despite this, estimates for the force of infection, infectious period and basic reproductive ratio-all necessary for the construction of dynamic transmission models-have not been obtained. By utilising three datasets each containing longitudinal infection information on individuals, we estimate each of these epidemiologically important parameters. With an eye to future study design, we also quantify the optimal sampling intervals for obtaining information about these parameters. We verify the estimation method through a simulation estimation study, and test each dataset to ensure suitability to the estimation method. We find that the force of infection differs by population prevalence, and the infectious period is estimated to be between 12 and 20 days. We also find that optimal sampling interval depends on setting, with an optimal sampling interval between 9 and 11 days in a high prevalence setting, and 21 and 27 days for a lower prevalence setting. These estimates unlock future model-based investigations on the transmission dynamics of skin sores.

Increasing incidence of invasive group A streptococcal disease in Western Australia, particularly among Indigenous people.

OBJECTIVE: To quantify the burden of invasive group A Streptococcus (GAS) disease in Western Australia during 2000-2018. DESIGN, SETTING: Population-based data linkage study: Hospital Morbidity Data Collection (HMDC; all WA public and private hospital records), PathWest pathology data (government-owned pathology services provider), and death registrations. PARTICIPANTS: People with invasive GAS disease, defined by an isolate from a normally sterile site (PathWest) or a hospital-based principal ICD-10-AM diagnosis code (HMDC). MAIN OUTCOME MEASURES: Incidence of invasive GAS disease; median length of hospital stay; all-cause mortality. RESULTS: We identified 2237 cases of GAS disease during 2000-2018; 1283 were in male patients (57%). 1950 cases had been confirmed by GAS isolates from normally sterile tissues (87%; including 1089 from blood [56% of cases] and 750 from tissue [38%]). The age-standardised incidence increased from 2.0 (95% CI, 1.4-2.7) cases per 100 000 population in 2000 to 9.1 (95% CI, 7.9-10.2) cases per 100 000 in 2017 (by year, adjusted for age group and sex: incidence rate ratio [IRR], 1.09; 95% CI, 1.08-1.10). Incidence was consistently higher among Indigenous than non-Indigenous Australians (year-adjusted IRR, 13.1; 95% CI, 11.3-15.1). All-cause 30-day mortality was 5% (116 deaths), and 90-day mortality 7% (156 deaths); 30-day mortality, adjusted for age group and sex, was not statistically significantly different for cases involving Indigenous or non-Indigenous patients (adjusted odds ratio, 0.8; 95% CI, 0.6-1.1). CONCLUSIONS: The incidence of invasive GAS disease in WA increased between 2000 and 2018, particularly among Indigenous Australians. Mandatory notification of invasive GAS disease would therefore be appropriate. The social determinants of differences in incidence should be addressed, and other relevant host, pathogen, and health system factors investigated.

Global, Regional, and National Burden of Rheumatic Heart Disease, 1990-2015.

BACKGROUND: Rheumatic heart disease remains an important preventable cause of cardiovascular death and disability, particularly in low-income and middle-income countries. We estimated global, regional, and national trends in the prevalence of and mortality due to rheumatic heart disease as part of the 2015 Global Burden of Disease study. METHODS: We systematically reviewed data on fatal and nonfatal rheumatic heart disease for the period from 1990 through 2015. Two Global Burden of Disease analytic tools, the Cause of Death Ensemble model and DisMod-MR 2.1, were used to produce estimates of mortality and prevalence, including estimates of uncertainty. RESULTS: We estimated that there were 319,400 (95% uncertainty interval, 297,300 to 337,300) deaths due to rheumatic heart disease in 2015. Global age-standardized mortality due to rheumatic heart disease decreased by 47.8% (95% uncertainty interval, 44.7 to 50.9) from 1990 to 2015, but large differences were observed across regions. In 2015, the highest age-standardized mortality due to and prevalence of rheumatic heart disease were observed in Oceania, South Asia, and central sub-Saharan Africa. We estimated that in 2015 there were 33.4 million (95% uncertainty interval, 29.7 million to 43.1 million) cases of rheumatic heart disease and 10.5 million (95% uncertainty interval, 9.6 million to 11.5 million) disability-adjusted life-years due to rheumatic heart disease globally. CONCLUSIONS: We estimated the global disease prevalence of and mortality due to rheumatic heart disease over a 25-year period. The health-related burden of rheumatic heart disease has declined worldwide, but high rates of disease persist in some of the poorest regions in the world. (Funded by the Bill and Melinda Gates Foundation and the Medtronic Foundation.).

Progress towards a coordinated, national paediatric antimicrobial resistance surveillance programme: Staphylococcus aureus, enterococcal and Gram-negative bacteraemia in Australia.

BACKGROUND: There is increasing knowledge of antimicrobial usage in children yet limited availability of nationally representative paediatric-specific data on antimicrobial resistance. OBJECTIVES: Paediatric data from this national surveillance programme are presented to explore differences between childhood and adult bloodstream infections and antimicrobial resistance surveillance. METHODS: Using information collected from a prospective coordinated antimicrobial resistance surveillance programme, children ≤18 years and adults >18 years with a positive blood culture for Staphylococcus aureus, Enterococcus spp. or Gram-negative spp. presenting to one of 34 Australian hospitals during 2013-16 were evaluated. Consistent methodologies for key sepsis pathogens were employed and a comparative analysis between children and adults was conducted. RESULTS: There are stark contrasts between children and adults in this national antimicrobial resistance (AMR) data set. Notable differences include lower rates of AMR, different clinical and molecular phenotypes and lower mortality amongst children. The burden of Gram-negative resistance is disproportionately experienced in children, with higher odds of death with an ESBL versus non-ESBL bacteraemia in comparison with adults. CONCLUSIONS: These data support that children are not just 'little adults' in the AMR era, and analyses by age group are important to detect differences in antibiotic susceptibility, clinical phenotype and genetic virulence factors. Antimicrobial surveillance incorporated into routine laboratory practice is vital to inform an array of wider applications including antimicrobial guidelines, stewardship and direction for prioritization of novel antimicrobial development.

Ending rheumatic heart disease in Australia: the evidence for a new approach.

■The RHD Endgame Strategy: the blueprint to eliminate rheumatic heart disease in Australia by 2031 (the Endgame Strategy) is the blueprint to eliminate rheumatic heart disease (RHD) in Australia by 2031. Aboriginal and Torres Strait Islander people live with one of the highest per capita burdens of RHD in the world. ■The Endgame Strategy synthesises information compiled across the 5-year lifespan of the End Rheumatic Heart Disease Centre of Research Excellence (END RHD CRE). Data and results from priority research projects across several disciplines of research complemented literature reviews, systematic reviews and narrative reviews. Further, the experiences of those working in acute rheumatic fever (ARF) and RHD control and those living with RHD to provide the technical evidence for eliminating RHD in Australia were included. ■The lived experience of RHD is a critical factor in health outcomes. All future strategies to address ARF and RHD must prioritise Aboriginal and Torres Strait Islander people's knowledge, perspectives and experiences and develop co-designed approaches to RHD elimination. The environmental, economic, social and political context of RHD in Australia is inexorably linked to ending the disease. ■Statistical modelling undertaken in 2019 looked at the economic and health impacts of implementing an indicative strategy to eliminate RHD by 2031. Beginning in 2019, the strategy would include: reducing household crowding, improving hygiene infrastructure, strengthening primary health care and improving secondary prophylaxis. It was estimated that the strategy would prevent 663 deaths and save the health care system $188 million. ■The Endgame Strategy provides the evidence for a new approach to RHD elimination. It proposes an implementation framework of five priority action areas. These focus on strategies to prevent new cases of ARF and RHD early in the causal pathway from Streptococcus pyogenes exposure to ARF, and strategies that address the critical systems and structural changes needed to support a comprehensive RHD elimination strategy.

The Path to Group A Streptococcus Vaccines: World Health Organization Research and Development Technology Roadmap and Preferred Product Characteristics.

Group A Streptococcus (GAS) infections result in a considerable underappreciated burden of acute and chronic disease globally. A 2018 World Health Assembly resolution calls for better control and prevention. Providing guidance on global health research needs is an important World Health Organization (WHO) activity, influencing prioritization of investments. Here, the role, status, and directions in GAS vaccines research are discussed. WHO preferred product characteristics and a research and development technology roadmap, briefly presented, offer an actionable framework for vaccine development to regulatory and policy decision making, availability, and use. GAS vaccines should be considered for global prevention of the range of clinical manifestations and associated antibiotic use. Impediments related to antigen diversity, safety concerns, and the difficulty to establish vaccine efficacy against rheumatic heart disease are discussed. Demonstration of vaccine efficacy against pharyngitis and skin infections constitutes a key near-term strategic goal. Investments and collaborative partnerships to diversify and advance vaccine candidates are needed.

Treatment, prevention and public health management of impetigo, scabies, crusted scabies and fungal skin infections in endemic populations: a systematic review.

We conducted a systematic review of the treatment, prevention and public health control of skin infections including impetigo, scabies, crusted scabies and tinea in resource-limited settings where skin infections are endemic. The aim is to inform strategies, guidelines and research to improve skin health in populations that are inequitably affected by infections of the skin and the downstream consequences of these. The systematic review is reported according to the PRISMA statement. From 1759 titles identified, 81 full text studies were reviewed and key findings outlined for impetigo, scabies, crusted scabies and tinea. Improvements in primary care and public health management of skin infections will have broad and lasting impacts on overall quality of life including reductions in morbidity and mortality from sepsis, skeletal infections, kidney and heart disease.

Nous avons effectué une analyse systématique du traitement, de la prévention et du contrôle de santé publique des infections cutanées comprenant l'impétigo, la gale, la gale en croûte et la teigne, dans des cadres à ressources limitées où les infections cutanées sont endémiques. Le but étant d'informer les stratégies, les directives et la recherche pour améliorer la santé de la peau dans les populations qui sont touchées de manière inéquitable par les infections cutanées et leurs conséquences plus tard. La revue systématique est rapportée selon la déclaration PRISMA. Sur 1759 titres recensés, 81 études en texte intégral ont été passées en revue et les principaux résultats rapportés concernant l'impétigo, la gale, la gale en croûte et la teigne. Les améliorations apportées dans la prise en charge des infections de la peau dans les soins de santé primaires et les soins de santé publique auront des répercussions vastes et durables sur la qualité de vie en général, notamment une réduction de la morbidité et de la mortalité dues au sepsis, aux infections du squelette, aux maladies du rein et du cœur.

Perinatal risk factors associated with skin infection hospitalisation in Western Australian Aboriginal and Non-Aboriginal children.

BACKGROUND: Hospitalisation with skin infection in Western Australian (WA) Aboriginal children is common, with the highest rates in infants and children from remote WA. OBJECTIVE: We aimed to quantify infant, maternal, and sociodemographic risk factors for skin infection hospitalisation in WA children, focussing on Aboriginal children aged <17 years. METHODS: We conducted a retrospective population-based cohort study with linked perinatal and hospitalisation data on WA-born children (1996-2012), of whom 31 348 (6.7%) were Aboriginal. We used Cox regression to calculate adjusted hazard ratios and associated population attributable fractions (PAFs) for perinatal factors attributed to first hospitalisation with skin infection. To identify specific risk factors for early-onset infection, we further restricted the cohort to infants aged <1 year. RESULTS: Overall, 5439 (17.4%) Aboriginal and 6750 (1.5%) non-Aboriginal children were hospitalised at least once with a skin infection. Aboriginal infants aged <1 year had the highest skin infection hospitalisation rate (63.2 per 1000 child-years). The strongest risk factors in Aboriginal children aged <17 years were socio-economic disadvantage, very remote location at birth, and multi-parity (≥3 previous pregnancies) accounting for 24%, 23%, and 15% of skin infection hospitalisations, respectively. Other risk factors included maternal age <20 years, maternal smoking during pregnancy, and low birthweight. CONCLUSIONS: We have quantified the relative influence of perinatal risk factors associated with skin infection hospitalisations in WA children, providing measures indicating which factors have the potential to reduce the most hospitalisations. Our evidence not only supports existing calls for substantial government investment in addressing underlying social and environmental barriers to healthy skin in WA Aboriginal children but also identifies potential areas to target health promotion messaging at individuals/families on maternal smoking during pregnancy and skin hygiene for families.

Standardizing clinical care measures of rheumatic heart disease in pregnancy: A qualitative synthesis.

BACKGROUND: Rheumatic heart disease (RHD) is a preventable cardiac condition that escalates risk in pregnancy. Models of care informed by evidence-based clinical guidelines are essential to optimal health outcomes. There are no published reviews that systematically explore approaches to care provision for pregnant women with RHD and examine reported measures. The review objective was to improve understanding of how attributes of care for these women are reported and how they align with guidelines. METHODS: A search of 13 databases was supported by hand-searching. Papers that met inclusion criteria were appraised using CASP/JBI checklists. A content analysis of extracted data from the findings sections of included papers was undertaken, informed by attributes of quality care identified previously from existing guidelines. RESULTS: The 43 included studies were predominantly conducted in tertiary care centers of low-income and middle-income countries. Cardiac guidelines were referred to in 25 of 43 studies. Poorer outcomes were associated with higher risk scores (detailed in 36 of 41 quantitative studies). Indicators associated with increased risk include anticoagulation during pregnancy (28 of 41 reported) and late booking (gestation documented in 15 of 41 studies). Limited access to cardiac interventions was discussed (19 of 43) in the context of poorer outcomes. Conversely, early assessment and access to regular multidisciplinary care were emphasized in promoting optimal outcomes for women and their babies. CONCLUSIONS: Despite often complex care requirements in challenging environments, pregnancy provides an opportunity to strengthen health system responses and address whole-of-life health for women with RHD. A standard set of core indicators is proposed to more accurately benchmark care pathways, outcomes, and burden.

Low positive predictive value of International Classification of Diseases, 10th Revision codes in relation to rheumatic heart disease: a challenge for global surveillance.

International Classification of Diseases, 10th Revision codes for rheumatic heart disease (RHD) include valvular heart disease of unspecified origin, limiting their usefulness for estimating RHD burden. A cross-disciplinary national consultation developed an algorithm to improve RHD identification in hospital data. The algorithm has been operationalised and piloted. The algorithm developed categorised 32% of RHD-coded patients as probable/possible RHD. We outline a series of research initiatives to improve identification of RHD in administrative data thereby contributing to monitoring the RHD burden globally.

Rheumatic heart disease in Timor-Leste school students: an echocardiography-based prevalence study.

OBJECTIVES: To determine the prevalence of rheumatic heart disease (RHD) in school-aged children and young people in Timor-Leste. DESIGN: Prospective cross-sectional survey. Echocardiography was performed by Australian cardiologists to determine the presence of RHD. Demographic data were also collected. Patients in whom RHD was detected were entered into a register to allow monitoring of adherence to secondary prophylaxis; the first dose of benzathine penicillin G (BPG) was administered on the day of screening. SETTING: Schools in urban (Dili) and rural (Ermera) Timor-Leste. PARTICIPANTS: School students aged 5-20 years. OUTCOME MEASURES: Definite and borderline RHD, as defined by World Heart Federation echocardiographic criteria. RESULTS: 1365 participants were screened; their median age was 11 years (IQR, 9-14 years), and 53% were girls. The estimated prevalence of definite RHD was 18.3 cases per 1000 population (95% CI, 12.3-27.0 per 1000), and of definite or borderline RHD 35.2 per 1000 (95% CI, 26.5-46.4 per 1000). Definite (adjusted odds ratio [aOR], 3.5; 95% CI, 1.3-9.4) and definite or borderline RHD (aOR, 2.7; 95% CI, 1.4-5.2) were more prevalent among girls than boys. Eleven children (0.8%) had congenital heart disease. Of the 25 children in whom definite RHD was identified, 21 (84%) received education and a first dose of BPG on the day of screening; all 25 have since received education about primary care for RHD and have commenced penicillin prophylaxis. CONCLUSIONS: The rates of RHD in Timor-Leste are among the highest in the world, and prevalence is higher among girls than boys. Community engagement is essential for ensuring follow-up and the effective delivery of secondary prophylaxis.

Genome-Wide Analysis of Genetic Risk Factors for Rheumatic Heart Disease in Aboriginal Australians Provides Support for Pathogenic Molecular Mimicry.

Background: Rheumatic heart disease (RHD) after group A streptococcus (GAS) infections is heritable and prevalent in Indigenous populations. Molecular mimicry between human and GAS proteins triggers proinflammatory cardiac valve-reactive T cells. Methods: Genome-wide genetic analysis was undertaken in 1263 Aboriginal Australians (398 RHD cases; 865 controls). Single-nucleotide polymorphisms were genotyped using Illumina HumanCoreExome BeadChips. Direct typing and imputation was used to fine-map the human leukocyte antigen (HLA) region. Epitope binding affinities were mapped for human cross-reactive GAS proteins, including M5 and M6. Results: The strongest genetic association was intronic to HLA-DQA1 (rs9272622; P = 1.86 × 10-7). Conditional analyses showed rs9272622 and/or DQA1*AA16 account for the HLA signal. HLA-DQA1*0101_DQB1*0503 (odds ratio [OR], 1.44; 95% confidence interval [CI], 1.09-1.90; P = 9.56 × 10-3) and HLA-DQA1*0103_DQB1*0601 (OR, 1.27; 95% CI, 1.07-1.52; P = 7.15 × 10-3) were risk haplotypes; HLA_DQA1*0301-DQB1*0402 (OR 0.30, 95%CI 0.14-0.65, P = 2.36 × 10-3) was protective. Human myosin cross-reactive N-terminal and B repeat epitopes of GAS M5/M6 bind with higher affinity to DQA1/DQB1 alpha/beta dimers for the 2-risk haplotypes than the protective haplotype. Conclusions: Variation at HLA_DQA1-DQB1 is the major genetic risk factor for RHD in Aboriginal Australians studied here. Cross-reactive epitopes bind with higher affinity to alpha/beta dimers formed by risk haplotypes, supporting molecular mimicry as the key mechanism of RHD pathogenesis.

Long-Term Outcomes From Acute Rheumatic Fever and Rheumatic Heart Disease: A Data-Linkage and Survival Analysis Approach.

BACKGROUND: We investigated adverse outcomes for people with acute rheumatic fever (ARF) and rheumatic heart disease (RHD) and the effect of comorbidities and demographic factors on these outcomes. METHODS: Using linked data (RHD register, hospital, and mortality data) for residents of the Northern Territory of Australia, we calculated ARF recurrence rates, rates of progression from ARF to RHD to severe RHD, RHD complication rates (heart failure, endocarditis, stroke, and atrial fibrillation), and mortality rates for 572 individuals diagnosed with ARF and 1248 with RHD in 1997 to 2013 (94.9% Indigenous). RESULTS: ARF recurrence was highest (incidence, 3.7 per 100 person-years) in the first year after the initial ARF episode, but low-level risk persisted for >10 years. Progression to RHD was also highest (incidence, 35.9) in the first year, almost 10 times higher than ARF recurrence. The median age at RHD diagnosis in Indigenous people was young, especially among males (17 years). The development of complications was highest in the first year after RHD diagnosis: heart failure incidence rate per 100 person-years, 9.09; atrial fibrillation, 4.70; endocarditis, 1.00; and stroke, 0.58. Mortality was higher among Indigenous than non-Indigenous RHD patients (hazard ratio, 6.55; 95% confidence interval, 2.45-17.51), of which 28% was explained by comorbid renal failure and hazardous alcohol use. RHD complications and mortality rates were higher for urban than for remote residents. CONCLUSIONS: This study provides important new prognostic information for ARF/RHD. The residual Indigenous survival disparity in RHD patients, which persisted after accounting for comorbidities, suggests that other factors contribute to mortality, warranting further research.

Rheumatic heart disease: infectious disease origin, chronic care approach.

BACKGROUND: Rheumatic heart disease (RHD) is a chronic cardiac condition with an infectious aetiology, causing high disease burden in low-income settings. Affected individuals are young and associated morbidity is high. However, RHD is relatively neglected due to the populations involved and its lower incidence relative to other heart diseases. METHODS AND RESULTS: In this narrative review, we describe how RHD care can be informed by and integrated with models of care developed for priority non-communicable diseases (coronary heart disease), and high-burden communicable diseases (tuberculosis). Examining the four-level prevention model (primordial through tertiary prevention) suggests primordial and primary prevention of RHD can leverage off existing tuberculosis control efforts, given shared risk factors. Successes in coronary heart disease control provide inspiration for similarly bold initiatives for RHD. Further, we illustrate how the Chronic Care Model (CCM), developed for use in non-communicable diseases, offers a relevant framework to approach RHD care. Systems strengthening through greater integration of services can improve RHD programs. CONCLUSION: Strengthening of systems through integration/linkages with other well-performing and resourced services in conjunction with policies to adopt the CCM framework for the secondary and tertiary prevention of RHD in settings with limited resources, has the potential to significantly reduce the burden of RHD globally. More research is required to provide evidence-based recommendations for policy and service design.