Controlling acute rheumatic fever and rheumatic heart disease in developing countries: are we getting closer?

A Longitudinal Study of Group A Streptococcal Colonization and Pharyngitis in US Children

BACKGROUND

Group A streptococci (GAS) are a major cause of pharyngitis in children. Recently, there were severe GAS outbreaks. The aims of this study were to assess pharyngeal colonization prevalence in healthy children, to assess different diagnostic definitions for GAS pharyngitis and to estimate incidence rates for these infections.

METHODS

A 2-year longitudinal study was conducted in healthy children in the United States. Pharyngeal swabs were cultured every 3 months for GAS colonization. Serum antistreptolysin O, antideoxyribonuclease B (DNaseB) and antistreptococcal C5a peptidase (SCP) antibody titers were assessed at baseline. When participants developed a sore throat, pharyngeal swabs were collected for rapid antigen detection test (RADT) and culture, and antibody titers were determined in serum samples. A range of case definitions were used for GAS pharyngitis.

RESULTS

A total of 422 children 3-12 years old were enrolled (140, 141 and 141 were 3-5, 6-9 and 10-12 years of age, respectively). The overall prevalence of GAS colonization during the study was 48%. Baseline antistreptolysin O, anti-DNaseB and anti-SCP antibody titers were higher for children older than 5 years. The incidence of GAS pharyngitis per 100 person-years was 15.9 for RADT/culture-proven and 4.6 for serologically confirmed pharyngitis.

CONCLUSIONS

GAS throat colonization and pharyngitis were frequent in children 3-12 years old. The case definition employed impacted the measured incidence of GAS pharyngitis, with higher rates detected using RADT/culture-based definitions. These data suggest that case definition is important and that young children are exposed to GAS, which may inform plans for vaccine development and implementation.

Mucosal Immunization Has Benefits over Traditional Subcutaneous Immunization with Group A Streptococcus Antigens in a Pilot Study in a Mouse Model

Group A Streptococcus (GAS) is a major human pathogen for which there is no licensed vaccine. To protect against infection, a strong systemic and mucosal immune response is likely to be necessary to prevent initial colonization and any events that might lead to invasive disease. A broad immune response will be necessary to target the varied GAS serotypes and disease presentations. To this end, we designed a representative panel of recombinant proteins to cover the stages of GAS infection and investigated whether mucosal and systemic immunity could be stimulated by these protein antigens. We immunized mice sublingually, intranasally and subcutaneously, then measured IgG and IgA antibody levels and functional activity through in vitro assays. Our results show that both sublingual and intranasal immunization in the presence of adjuvant induced both systemic IgG and mucosal IgA. Meanwhile, subcutaneous immunization generated only a serum IgG response. The antibodies mediated binding and killing of GAS cells and blocked binding of GAS to HaCaT cells, particularly following intranasal and subcutaneous immunizations. Further, antigen-specific assays revealed that immune sera inhibited cleavage of IL-8 by SpyCEP and IgG by Mac/IdeS. These results demonstrate that mucosal immunization can induce effective systemic and mucosal antibody responses. This finding warrants further investigation and optimization of humoral and cellular responses as a viable alternative to subcutaneous immunization for urgently needed GAS vaccines.

Tertiary prevention and treatment of rheumatic heart disease: a National Heart, Lung, and Blood Institute working group summary

Although entirely preventable, rheumatic heart disease (RHD), a disease of poverty and social disadvantage resulting in high morbidity and mortality, remains an ever-present burden in low-income and middle-income countries (LMICs) and rural, remote, marginalised and disenfranchised populations within high-income countries. In late 2021, the National Heart, Lung, and Blood Institute convened a workshop to explore the current state of science, to identify basic science and clinical research priorities to support RHD eradication efforts worldwide. This was done through the inclusion of multidisciplinary global experts, including cardiovascular and non-cardiovascular specialists as well as health policy and health economics experts, many of whom also represented or closely worked with patient-family organisations and local governments. This report summarises findings from one of the four working groups, the Tertiary Prevention Working Group, that was charged with assessing the management of late complications of RHD, including surgical interventions for patients with RHD. Due to the high prevalence of RHD in LMICs, particular emphasis was made on gaining a better understanding of needs in the field from the perspectives of the patient, community, provider, health system and policy-maker. We outline priorities to support the development, and implementation of accessible, affordable and sustainable interventions in low-resource settings to manage RHD and related complications. These priorities and other interventions need to be adapted to and driven by local contexts and integrated into health systems to best meet the needs of local communities.

IgG2 rules: N-acetyl-β-D-glucosamine-specific IgG2 and Th17/Th1 cooperation may promote the pathogenesis of acute rheumatic heart disease and be a biomarker of the autoimmune sequelae of Streptococcus pyogenes

Antecedent group A streptococcal pharyngitis is a well-established cause of acute rheumatic fever (ARF) where rheumatic valvular heart disease (RHD) and Sydenham chorea (SC) are major manifestations. In ARF, crossreactive antibodies and T cells respond to streptococcal antigens, group A carbohydrate, N-acetyl-β-D-glucosamine (GlcNAc), and M protein, respectively, and through molecular mimicry target heart and brain tissues. In this translational human study, we further address our hypothesis regarding specific pathogenic humoral and cellular immune mechanisms leading to streptococcal sequelae in a small pilot study. The aims of the study were to (1) better understand specific mechanisms of pathogenesis in ARF, (2) identify a potential early biomarker of ARF, (3) determine immunoglobulin G (IgG) subclasses directed against GlcNAc, the immunodominant epitope of the group A carbohydrate, by reaction of ARF serum IgG with GlcNAc, M protein, and human neuronal cells (SK-N-SH), and (4) determine IgG subclasses deposited on heart tissues from RHD. In 10 pediatric patients with RHD and 6 pediatric patients with SC, the serum IgG2 subclass reacted significantly with GlcNAc, and distinguished ARF from 7 pediatric patients with uncomplicated pharyngitis. Three pediatric patients who demonstrated only polymigrating arthritis, a major manifestation of ARF and part of the Jones criteria for diagnosis, lacked the elevated IgG2 subclass GlcNAc-specific reactivity. In SC, the GlcNAc-specific IgG2 subclass in cerebrospinal fluid (CSF) selectively targeted human neuronal cells as well as GlcNAc in the ELISA. In rheumatic carditis, the IgG2 subclass preferentially and strongly deposited in valve tissues (n = 4) despite elevated concentrations of IgG1 and IgG3 in RHD sera as detected by ELISA to group A streptococcal M protein. Although our human study of ARF includes a very small limited sample set, our novel research findings suggest a strong IgG2 autoantibody response against GlcNAc in RHD and SC, which targeted heart valves and neuronal cells. Cardiac IgG2 deposition was identified with an associated IL-17A/IFN-γ cooperative signature in RHD tissue which displayed both IgG2 deposition and cellular infiltrates demonstrating these cytokines simultaneously. GlcNAc-specific IgG2 may be an important autoantibody in initial stages of the pathogenesis of group A streptococcal sequelae, and future studies will determine if it can serve as a biomarker for risk of RHD and SC or early diagnosis of ARF.

Medium-term outcomes from mitral valve surgery for rheumatic heart disease in young adults in Aotearoa New Zealand: a cohort study

BACKGROUND

Rheumatic heart disease (RHD) remains an important cause of morbidity and mortality in New Zealand. Factors associated with the choice of surgical treatment for advanced RHD in young adults are poorly understood. We sought to review our local experience with the surgical management of young adults with rheumatic mitral valvular disease.

METHODS

From 2003 to 2016, all patients aged 15-24 years undergoing mitral valve surgery for rheumatic disease at Auckland City Hospital, New Zealand were retrospectively reviewed.

RESULTS

During the 13-year study period, 73 young adults underwent mitral surgery; 85% were Maori or Pacific Islanders. Mitral repair was performed in 32 patients and replacement in 41 patients. Isolated mitral valve surgery was performed in 36%, double valve procedures in 47%, and triple valve procedures in 17% of patients. The 30-day mortality rate and stroke rate were 1.4% and 2.7% respectively. The medium-term mortality rate was 11.9% across a mean follow-up of 6 years (6.9% in the repair group, 15.8% in the replacement group, p = 0.25). There were increased bleeding complications (p = 0.04) in patients with mechanical mitral valve replacement. For patients on warfarin, across medium-term follow-up, the INR was in the therapeutic range only 23% of the time.

CONCLUSION

Most young adults in New Zealand with severe RHD requiring surgery are of indigenous Maori or Pacific Island ethnicity. There is a trend towards improved survival with mitral repair. There is a significant tendency towards increased bleeding complications in patients on warfarin for mechanical mitral replacement. Warfarin compliance is poor.

Pediatric rheumatic carditis in Italy and Rwanda: The same disease, different socio-economic settings

BACKGROUND

Acute Rheumatic Fever and Rheumatic Heart Disease are the leading cause of acquired heart disease in Low-Income Countries, and a common cause in High-Income Countries. We compared rheumatic carditis, its echocardiographic presentation at diagnosis and its progression in Italy and Rwanda.

METHODS

Retrospective study including all consecutive patients diagnosed with rheumatic carditis in an Italian (IT) and two Rwandan Hospitals (RW). Echocardiography was performed at diagnosis and three follow-up visits. Baseline characteristics, history of primary and secondary prophylaxis and cardiovascular complications data were collected.

RESULTS

Seventy-nine and 135 patients were enrolled in IT and RW, respectively. Mitral regurgitation was the most common lesion (IT: 70%, RW: 96%) in both cohorts; mixed valve lesions and severe lesions were more prevalent in RW. Age at diagnosis (IT: 8.4 ± 2.9 yrs.; RW: 11.1 ± 2.7 yrs.; P < 0.001), adherence to secondary prophylaxis (IT: 99%; RW: 48%; P < 0.001) and history of primary prophylaxis (IT: 65%; RW: 6%; P < 0.001) were different. During the follow-up, native valve lesions completely resolved in 38% of IT and in 2% of RW patients (P < 0.001). By contrast, cardiac surgery was performed in 31% of RW and 5% of IT patients (P < 0.001). Cardiovascular complications and death were only observed in RW.

CONCLUSIONS

The more severe cardiac involvement, the higher rate of valve surgery, CV complications and deaths in RW, could be due to delayed diagnosis and treatment, scarce adherence to secondary prophylaxis and differences in social determinants of health.

Echocardiographic screening for rheumatic heart disease in Turkish schoolchildren

BACKGROUND

The aim of this study is to investigate the prevalence of subclinical rheumatic heart disease in schoolchildren aged 5-18 by using portable echocardiography in Ankara, Turkey.

METHODS

The portable echocardiography screening was performed by a paediatric cardiologist for all of the cases. The mean age of 2550 healthy students was 11.09 ± 2.91 years (1339 females, 1211 males) in three private and three public schools. Echocardiographic studies were assessed according to 2012 World Heart Federation criteria for rheumatic heart disease.

RESULTS

After reviewing the echocardiographic images, 73 students were reevaluated by an advanced echocardiography device in the university hospital. Evidence of definite subclinical rheumatic heart disease was found in 39 students (15/1000) and borderline rheumatic heart disease in 20 students (8/1000). No children had any clinical symptoms. The mean age of children diagnosed with rheumatic heart disease and borderline rheumatic heart disease is 12.4 and 11.4 years, respectively. The risk of rheumatic heart disease was found to be increased sevenfold in girls between 14 and 18 years. We surprisingly observed that the prevalence of definite rheumatic heart disease in private schools located in high-income areas of Ankara was higher than that in public schools.

CONCLUSIONS

This is the first and largest single-centred echocardiographic screening study for subclinical rheumatic heart disease in Turkish schoolchildren. The frequency of rheumatic heart disease has been found to be 15/1000. This finding is similar to those of recent echocardiographic screening studies performed in middle and high-risk populations. We conclude that to decrease the burden of rheumatic heart disease, echocardiographic screening studies are necessary, and long-term follow-up of children with echocardiographically diagnosed subclinical rheumatic heart disease is needed.

The effect of group A streptococcal carrier on the epidemic model of acute rheumatic fever

Background

Group A streptococcus (GAS) is the most frequent cause of bacterial pharyngitis in school-aged children. The postinfection sequel as acute rheumatic fever (ARF) and rheumatic heart disease that cause morbidity and mortality among young people is public health concerns in several developing countries. Asymptomatic carriage state of GAS is not fully understood in terms of host and bacterial factors. Although the ability of transmitting GAS of the asymptomatic carriers is relatively low, they may present the reservoir of the epidemic. A fraction of GAS carriers is difficult to estimate in practice and may greatly vary between populations. Understanding the role of carriage on the transmission dynamic of GAS is important for assessing the public health impact of the ARF.

Method

This study investigates the effect of GAS carriers on both the transmission and dynamic of ARF cases by using a mathematical model.

Result

We derive the sufficient conditions for which the GAS can spread or extinct from the naive population under the variation of the fraction of symptomatic cases over the incidence of GAS. The threshold is possible to occur in general, but the last condition which is rather restrictive and involves parameter uncertainty. The increasing of carriers in the endemic state leads to the reduction in magnitude of the reproduction number and the number of ARF patients. We demonstrate that the adjustment of parameters can be carried out by the use of endemic state and some specific data.

Conclusion

We show theoretically that the presence of asymptomatic carriers may induce the epidemic threshold and reduce the virulence of GAS and the prevalence of ARF.

A population pharmacokinetic study of benzathine benzylpenicillin G administration in children and adolescents with rheumatic heart disease: new insights for improved secondary prophylaxis strategies

BACKGROUND

Benzathine benzylpenicillin G (BPG) is recommended as secondary prophylaxis to prevent recurrence of acute rheumatic fever and subsequent rheumatic heart disease (RHD). Following intramuscular injection, BPG is hydrolysed to benzylpenicillin. Little is known of the pharmacokinetics of benzylpenicillin following BPG in populations at risk of RHD.

METHODS

We conducted a longitudinal pharmacokinetic study of children and adolescents receiving secondary prophylaxis throughout six monthly cycles of BPG. Dried blood spot samples were assayed with LC-MS/MS. Benzylpenicillin concentrations were analysed using non-linear mixed-effects modelling with subsequent simulations based on published BMI-for-age and weight-for-age data.

RESULTS

Eighteen participants contributed 256 concentrations for analysis. None had benzylpenicillin concentrations >0.02 mg/L for the full time between doses. The median duration above this target was 9.8 days for those with a lower BMI (<25 kg/m2), who also had lower weights, and 0 days for those with a higher BMI (≥25 kg/m2). Although fat-free mass was a key determinant of benzylpenicillin exposure after a standard dose of BPG, having a higher BMI influenced absorption and almost doubled (increase of 86%) the observed t½.

CONCLUSIONS

Few children and adolescents receiving BPG as secondary prophylaxis will achieve concentrations >0.02 mg/L for the majority of the time between injections. The discordance of this observation with reported efficacy of BPG to prevent rheumatic fever implies a major knowledge gap relating to pharmacokinetic/pharmacodynamic relationships between benzylpenicillin exposure and clinical outcomes.

Heart transplantation outcomes for rheumatic heart disease: Analysis of international registry data

BACKGROUND

Rheumatic heart disease (RHD), an autoimmune sequela of Group A streptococcal infection, is a chronic valvular disease affecting 32 million people worldwide, predominantly in developing nations. As the predisposition to autoimmune sequela still remains post transplantation, our primary objective was to assess if there were differences in mortality and rejection rates.

METHODS AND RESULTS

Using the International Society for Heart and Lung Transplantation (ISHLT) adult heart transplant registry, we identified 42 RHD patients who had undergone heart transplantation between 1988 and 2014. We matched the 42 RHD recipients by transplant year, age, and gender to 420 dilated cardiomyopathy (DCM) recipients. One-year mortality in the RHD group was 17.95% vs. 7.92% in the DCM group (P = 0.07). Survival was significantly reduced in the RHD group vs. the DCM group via Kaplan Meier curves (P = 0.04). In a multivariate model, RHD status (OR 3.19, 95% CI 1.15-8.83, P = 0.025) and serum creatinine (OR 1.41, 95% CI 1.09-1.82, P = 0.009) were associated with an increased odds of one-year mortality (P = 0.0013).

CONCLUSIONS

At one year post transplantation, RHD recipients had a significantly lower survival than DCM recipients. RHD status was also an independent predictor of mortality at 1 year post transplantation.

"That Heart Sickness": Young Aboriginal People's Understanding of Rheumatic Fever

High rates of acute rheumatic fever (ARF) and rheumatic heart disease (RHD) in Australia predominate in young Aboriginal people highlighting underlying racial and equity issues.  This article focuses on the perceptions of the disease among young Aboriginal people living in remote Australia. Participant understanding was constrained by clinicians' use of language rooted in biomedicine and delivered through English, a second language for all participants. Clinicians' communicative competency is a social determinant of Aboriginal health. We recommend that the use of Aboriginal languages be prioritized in health services caring for Aboriginal people and that biomedical dominance in the services be relinquished.

Acquired heart disease in low-income and middle-income countries

The burden of illness associated with acquired cardiac disease in children in low-income and middle-income countries (LMIC) is significant and may be equivalent to that of congenital heart disease. Rheumatic heart disease, endomyocardial fibrosis, cardiomyopathy (including HIV cardiomyopathy) and tuberculosis are the most important causes. All are associated with poverty with the neediest children having the least access to care. The associated mortality and morbidity is high. There is an urgent need to improve cardiac care in LMIC, particularly in sub-Saharan Africa and parts of Southeast Asia where the burden is highest.

The novel Group A Streptococcus antigen SpnA combined with bead-based immunoassay technology improves streptococcal serology for the diagnosis of acute rheumatic fever

OBJECTIVES

Streptococcal serology provides evidence of prior Group A Streptococcus (GAS) exposure, crucial to the diagnosis of acute rheumatic fever (ARF) and post-streptococcal glomerulonephritis. However, current tests, which measure anti-streptolysin-O and anti-DNaseB antibodies, are limited by false positives in GAS endemic settings, and incompatible methodology requiring the two tests to be run in parallel. The objective was to improve streptococcal serology by combining the novel GAS antigen, SpnA, with streptolysin-O and DNaseB in a contemporary, bead-based immunoassay.

METHODS

Recombinant streptolysin-O, DNAseB and SpnA were conjugated to polystyrene beads with unique fluorescence positions so antibody binding to all three antigens could be detected simultaneously by cytometric bead array. Multiplex assays were run on sera collected in three groups: ARF; ethnically matched healthy children; and healthy adults.

RESULTS

The ability of the antigens to detect a previous GAS exposure in ARF was assessed using the 80th centile of the healthy children group as cut-off (upper limit of normal). SpnA had the highest sensitivity at 88%, compared with 75% for streptolysin-O and 56% for DNaseB.

CONCLUSIONS

SpnA has favorable immunokinetics for streptococcal serology, and can be combined with anti-streptolysin-O and anti-DNaseB in a multiplex format to improve efficiency and accuracy.

Zinc'ing it out: zinc homeostasis mechanisms and their impact on the pathogenesis of human pathogen group A streptococcus

Group A Streptococccus (GAS) is a major human pathogen that causes significant morbidity and mortality. Zinc is an essential trace element required for GAS growth, however, zinc can be toxic at excess concentrations. The bacterial strategies to maintain zinc sufficiency without incurring zinc toxicity play a crucial role in host-GAS interactions and have a significant impact on GAS pathogenesis. The host deploys nutritional immune mechanisms to retard GAS growth by causing either zinc deprivation or zinc poisoning. However, GAS overcomes the zinc-dependent host defenses and survives in the hostile environment by employing complex adaptive strategies. In this review, we describe the different host immune strategies that employ either zinc limitation or zinc toxicity in different host environments to control GAS infection. We also discuss the molecular mechanisms and machineries used by GAS to evade host nutritional defenses and establish successful infection. Emerging evidence suggests that the metal transporters are major GAS virulence factors as they compete against host nutritional immune mechanisms to acquire or expel metals and promote bacterial survival in the host. Thus, identification of GAS molecules and elucidation of the mechanisms by which GAS combats host-mediated alterations in zinc availability may lead to novel interference strategies targeting GAS metal acquisition systems.

Penicillin Dried Blood Spot Assay for Use in Patients Receiving Intramuscular Benzathine Penicillin G and Other Penicillin Preparations To Prevent Rheumatic Fever

Rheumatic heart disease (RHD) remains an important global health challenge. Administration of benzathine penicillin (BPG) every 3 to 4 weeks is recommended as a secondary prophylaxis to prevent recurrent episodes of acute rheumatic fever and subsequent RHD. Following intramuscular injection, BPG is hydrolyzed to penicillin G (benzylpenicillin). However, little is known of the pharmacokinetics (PK) of BPG in pediatric populations at high risk of RHD or of the pharmacokinetic-pharmacodynamic relationship between penicillin exposure and clinically relevant outcomes. Dried blood spot (DBS) assays can facilitate PK studies in situations where frequent venous blood sampling is logistically difficult. A liquid chromatography-mass spectroscopy assay for penicillin G in plasma and DBS was developed and validated. Application of the DBS assay for PK studies was confirmed using samples from adult patients receiving penicillin as part of an infection management plan. The limit of quantification for penicillin G in DBS was 0.005 mg/liter. Penicillin G is stable in DBS for approximately 12 h at room temperature (22°C), 6 days at 4°C, and >1 month at -20°C. Plasma and DBS penicillin G concentrations for patients receiving BPG and penicillin G given via bolus doses correlated well and had comparable time-concentration profiles. There was poor correlation for patients receiving penicillin via continuous infusions, perhaps as a result of the presence of residual penicillin in the peripherally inserted central catheter, from which the plasma samples were collected. The present DBS penicillin G assay can be used as a surrogate for plasma concentrations to provide valid PK data for studies of BPG and other penicillin preparations developed to prevent rheumatic fever and RHD.

The WHF Roadmap for Reducing CV Morbidity and Mortality Through Prevention and Control of RHD

Rheumatic heart disease (RHD) is a preventable non-communicable condition that disproportionately affects the world's poorest and most vulnerable. The World Heart Federation Roadmap for improved RHD control is a resource designed to help a variety of stakeholders raise the profile of RHD nationally and globally, and provide a framework to guide and support the strengthening of national, regional and global RHD control efforts. The Roadmap identifies the barriers that limit access to and uptake of proven interventions for the prevention and control of RHD. It also highlights a variety of established and promising solutions that may be used to overcome these barriers. As a general guide, the Roadmap is meant to serve as the foundation for the development of tailored plans of action to improve RHD control in specific contexts.

Atrial fibrillation

Atrial fibrillation (AF) is the most common sustained cardiac rhythm disorder, and increases in prevalence with increasing age and the number of cardiovascular comorbidities. AF is characterized by a rapid and irregular heartbeat that can be asymptomatic or lead to symptoms such as palpitations, dyspnoea and dizziness. The condition can also be associated with serious complications, including an increased risk of stroke. Important recent developments in the clinical epidemiology and management of AF have informed our approach to this arrhythmia. This Primer provides a comprehensive overview of AF, including its epidemiology, mechanisms and pathophysiology, diagnosis, screening, prevention and management. Management strategies, including stroke prevention, rate control and rhythm control, are considered. We also address quality of life issues and provide an outlook on future developments and ongoing clinical trials in managing this common arrhythmia.

Echocardiographic screening for rheumatic heart disease-some answers, but questions remain

Despite being preventable, rheumatic heart disease (RHD) remains a significant global cause of cardiovascular disease. Echocardiographic screening for early detection of RHD has the potential to enable timely commencement of treatment (secondary prophylaxis) to halt progression to severe valvular disease. However, a number of issues remain to be addressed regarding its feasibility. The natural history of Definite RHD without a prior history of acute rheumatic fever (ARF) and Borderline RHD are both unclear. Even if they are variants of RHD it is not known whether secondary antibiotic prophylaxis will prevent disease progression as it does in "traditionally" diagnosed RHD. False positives can also have a detrimental impact on individuals and their families as well as place substantial burdens on health care systems. Recent research suggests that handheld echocardiography (HAND) may offer a cheaper and more convenient alternative to standard portable echocardiography (STAND) in RHD screening. However, while HAND is sensitive for the detection of Definite RHD, it is less sensitive for Borderline RHD and is relatively poor at detecting mitral stenosis (MS). Given its attendant limited specificity, potential cases detected with HAND would require re-examination by standard echocardiography. For now, echocardiographic screening for RHD should remain a subject of research rather than routine health care.