Risk factors for acute rheumatic fever: A case-control study

Low-dose interleukin 2 therapy halts the progression of post-streptococcal autoimmune complications in a rat model of rheumatic heart disease

Acute rheumatic fever (ARF) is an autoimmune disease triggered by antibodies and T cells targeting the group A Streptococcus (GAS, Strep A) bacterium, often leading to rheumatic heart disease (RHD) and Sydenham's chorea. Long-term monthly penicillin injections are recognized as a cornerstone of public health programs to prevent Strep A reinfection and progression of ARF. However, compliance is poor, and better tools are required to slow disease progression. Preclinical evidence suggests that this can be achieved. Using a rat model that replicates post-streptococcal autoimmune complications, we explored the potential of low-dose interleukin-2 (LD-IL-2) as an immunotherapeutic intervention for ARF/RHD. In this model, injections of recombinant M protein from Strep A type 5 (rM5) to Lewis rats induce cardiac tissue inflammation, conduction abnormalities, and cross-reactive antibodies against cardiac and brain proteins central to disease pathogenesis. In animals injected with rM5 and treated with LD-IL-2, no cardiac functional or histological changes was observed. LD-IL-2 therapy effectively reduced the production of cross-reactive antibodies raised against host proteins and significantly increased regulatory T cells in the mediastinal lymph nodes. These novel findings suggest that LD-IL-2 will be an effective immunotherapeutic agent for treating ARF and has the potential to replace the standard monthly penicillin injections.

IMPORTANCE

Post-streptococcal autoimmune syndromes, including acute rheumatic fever, rheumatic heart disease, and Sydenham's chorea, represent a significant yet often under-recognized health and economic burden. This is especially true in low-income countries and among Indigenous populations in high-income nations, where the disease burden is most severe. These conditions arise from an autoimmune response to group A Streptococcus infections, leading to long-term health complications, disability, and premature death. Despite their widespread impact, no vaccine is currently available to prevent reinfections, and no specific therapy exists to treat the resulting autoimmune process. This study uses a rat model of rheumatic heart disease to evaluate the potential of low-dose interleukin 2 therapy in improving clinical outcomes and reducing the incidence of autoimmune diseases triggered by streptococcal infections.

Global, Regional, and National Burden of Valvular Heart Disease, 1990 to 2021

BACKGROUND

Valvular heart disease poses an escalating global health challenge with an increasing impact on mortality and disability. This study aims to comprehensively analyze the global burden of valvular heart disease.

METHODS AND RESULTS

Using the Global Burden of Disease 2021 data, we analyzed the prevalence and disability-adjusted life years, examining implications across demographics and geographic regions. In 2021, an estimated 54.8 million (95% uncertainty interval [UI], 43.3-67.6) cases of rheumatic heart disease, 13.3 million (95% UI, 11.4-15.2) cases of nonrheumatic calcific aortic valve disease (CAVD), and 15.5 million (95% UI, 14.5-16.7) cases of nonrheumatic degenerative mitral valve disease (DMVD) were reported globally. Despite the rising prevalence, disability-adjusted life years declined between 1991 and 2021. Among individuals aged 70 years or older, the age-standardized prevalences were 1803.6 per 100 000 (95% UI, 1535.5-2055.7) for CAVD and 2148.9 per 100 000 (95% UI, 2001.4-2310.1) for DMVD. Sub-Saharan Africa had the highest age-standardized prevalence for rheumatic heart disease; Conversely, high-income regions led in CAVD and DMVD prevalence. Rheumatic heart disease had the highest age-standardized prevalence of 1184.2 per 100 000 (95% UI, 932.4-1478.2) in low Socio-Demographic Index (SDI) regions, whereas CAVD peaked at 349.8 per 100 000 (95% UI, 303.6-395.8) in high SDI regions. The most substantial increases in age-standardized prevalences of CAVD from 1990 to 2021 occurred in the middle SDI and low-middle SDI regions. A parallel trend was noted for DMVD.

CONCLUSIONS

Rheumatic heart disease remains a significant burden in low SDI regions, whereas CAVD and DMVD pose challenges in high SDI regions with aging populations.

Systematic Review of Household Transmission of Strep A: A Potential Site for Prevention That Has Eluded Attention

BACKGROUND

Although Streptococcus pyogenes (Strep A) is the sixth-most common infectious disease globally, its transmission within the household remains an understudied driver of infection. We undertook a systematic review to better understand the transmission of Strep A among people within the home, while highlighting opportunities for prevention.

METHODS

A search strategy was applied to 5 databases between September 2022 and March 2023. Results were limited to articles published between January 2000 and March 2023. Texts were reviewed by 2 authors and the following data extracted: article details (title, author, year), study type, transmission year, country, participant age, infection status, molecular testing, and transmission mode. Funding was provided by the Australian National Health and Medical Research Council (GNT2010716).

RESULTS

The final analysis comprised 28 texts. Only 7 studies (25.0%) provided sufficient detail to identify the Strep A transmission mode: contact (n = 4), vehicle (bedding, clothing, other fabric, and medical equipment; n = 2), and contact with animals (n = 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.

An acute rheumatic fever immune signature comprising inflammatory markers, IgG3, and Streptococcus pyogenes-specific antibodies

Understanding the immune profile of acute rheumatic fever (ARF), a serious post-infectious sequelae of Streptococcal pyogenes (group A Streptococcus [GAS]), could inform disease pathogenesis and management. Circulating cytokines, immunoglobulins, and complement were analyzed in participants with first-episode ARF, swab-positive GAS pharyngitis and matched healthy controls. A striking elevation of total IgG3 was observed in ARF (90% > clinical reference range for normal). ARF was also associated with an inflammatory triad with significant correlations between interleukin-6, C-reactive protein, and complement C4 absent in controls. Quantification of GAS-specific antibody responses revealed that subclass polarization was remarkably consistent across the disease spectrum; conserved protein antigens polarized to IgG1, while M-protein responses polarized to IgG3 in all groups. However, the magnitude of responses was significantly higher in ARF. Taken together, these findings emphasize the association of exaggerated GAS antibody responses, IgG3, and inflammatory cytokines in ARF and suggest IgG3 testing could beneficially augment clinical diagnosis.

The roles of immuno-modulator treatment and echocardiographic screening in rheumatic fever and rheumatic heart disease control: research from Aotearoa, New Zealand

This review summarises advances in research from Aotearoa, New Zealand (NZ) that have potential to reduce the inequitable distribution of acute rheumatic fever (ARF) and rheumatic heart disease (RHD). ARF incidence and RHD prevalence are unacceptably inequitable for Māori and Pacifica. Recent qualitative research has demonstrated mismatches between the lived experience of those with ARF/RHD and health service experience they encounter. NZ-led research has contributed knowledge to all stages of disease prevention (primordial, primary and secondary) and for tertiary management. Modifiable risk factors for ARF are racism across health sectors, household crowding, barriers to accessing primary health care, a high intake of sugar-sweetened beverages and preceding sore throat and skin infections. NZ research has evaluated the impact of a large-scale sore throat management programme and Streptococcal A vaccine development. This review highlights two programme domains of research by the authors that have the potential to reduce the burden of chronic RHD: firstly, effective immunomodulation of ARF to reduce the severity of carditis, with current clinical trials of hydroxychloroquine in NZ; secondly, the development of echocardiographic screening of previously undetected RHD. This now meets criteria for an effective screening test and has potential translation for disease control of RHD.

A worldwide population of Streptococcus pyogenes strains circulating among school-aged children in Auckland, New Zealand: a genomic epidemiology analysis

Background

Acute rheumatic fever (ARF) is a serious post-infectious sequala of Group A Streptococcus (GAS, Streptococcus pyogenes). In New Zealand (NZ) ARF is a major cause of health inequity. This study describes the genomic analysis of GAS isolates associated with childhood skin and throat infections in Auckland NZ.

Methods

Isolates (n = 469) collected between March 2018 and October 2019 from the throats and skin of children (5-14 years) underwent whole genomic sequencing. Equal representation across three ethnic groups was ensured through sample quotas with isolates obtained from Indigenous Māori (n = 157, 33%), NZ European/Other (n = 149, 32%) and Pacific Peoples children (n = 163, 35%). Using in silico techniques isolates were classified, assessed for diversity, and examined for distribution differences between groups. Comparisons were also made with GAS strains identified globally.

Findings

Genomic analysis revealed a diverse population consisting of 65 distinct sequence clusters. These sequence clusters spanned 49 emm-types, with 11 emm-types comprised of several, distinct sequence clusters. There is evidence of multiple global introductions of different lineages into the population, as well as local clonal expansion. The M1UK lineage comprised 35% of all emm1 isolates.

Interpretation

The GAS population was characterized by a high diversity of strains, resembling patterns observed in low- and middle-income countries. However, strains associated with outbreaks and antimicrobial resistance commonly found in high-income countries were also observed. This unique combination poses challenges for vaccine development, disease management and control.

Funding

The work was supported by the Health Research Council of New Zealand (HRC), award number 16/005.

Children's scabies survey indicates high prevalence and misdiagnosis in Auckland educational institutions

AIM

Here, we present results of a survey of scabies prevalence in childcare centres and primary schools in Auckland.

METHODS

Children whose parents agreed to take part in participating centres in the Auckland region were examined for scabies by general practitioners and given questionnaires of relevant symptoms. Diagnoses of clinical or suspected scabies were made according to the International Alliance for the Control of Scabies (IACS) criteria. The survey was a stratified random sample of schools and early childcare centres. A quantitative polymerase chain reaction (PCR) test was also used to complement the IACS criteria.

RESULTS

A total of 181 children were examined, with 145 children with history information, 16 of whom (11.0%) met the criteria for 'clinical' or 'suspected' scabies. Weighted analysis, accounting for the survey design, indicated that the prevalence of scabies in early childcare centres was 13.2% (95% CI: 4.3 to 22.1), with no school-aged children fulfilling these criteria. A higher proportion had clinical signs of scabies with 23 (12.7%) having typical scabies lesions and a further 43 (23.8%) had atypical lesions. A total of 64 PCR tests were taken and 15 (23%) were positive. None of these cases were receiving treatment for scabies. Five were undergoing topical skin treatment: three with topical steroid and two with calamine lotion.

CONCLUSIONS

The prevalence of children with scabies is high in early childcare centres in Auckland. Misdiagnosis is suggested by several PCR positive cases being treated by topical agents used to treat other skin conditions.

Research priorities for the primordial prevention of acute rheumatic fever and rheumatic heart disease by modifying the social determinants of health

The social determinants of health (SDH), such as access to income, education, housing and healthcare, strongly shape the occurrence of acute rheumatic fever (ARF) and rheumatic heart disease (RHD) at the household, community and national levels. The SDH are systemic factors that privilege some more than others and result in poverty and inequitable access to resources to support health and well-being. Primordial prevention is the modification of SDH to improve health and reduce the risk of disease acquisition and the subsequent progression to RHD. Modifying these determinants using primordial prevention strategies can reduce the risk of exposure to Group A Streptococcus, a causative agent of throat and skin infections, thereby lowering the risk of initiating ARF and its subsequent progression to RHD.This report summarises the findings of the Primordial Prevention Working Group-SDH, which was convened in November 2021 by the National Heart, Lung, and Blood Institute to assess how SDH influence the risk of developing RHD. Working group members identified a series of knowledge gaps and proposed research priorities, while recognising that community engagement and partnerships with those with lived experience will be integral to the success of these activities. Specifically, members emphasised the need for: (1) global analysis of disease incidence, prevalence and SDH characteristics concurrently to inform policy and interventions, (2) global assessment of legacy primordial prevention programmes to help inform the co-design of interventions alongside affected communities, (3) research to develop, implement and evaluate scalable primordial prevention interventions in diverse settings and (4) research to improve access to and equity of services across the RHD continuum. Addressing SDH, through the implementation of primordial prevention strategies, could have broader implications, not only improving RHD-related health outcomes but also impacting other neglected diseases in low-resource settings.

Pediatric Rheumatic Fever With Acute Fulminant Carditis: A Case Report

Acute rheumatic fever (ARF) is a multi-system inflammatory autoimmune disease. It is a significant cause of heart disease and early death worldwide, especially in children in developing countries. We present a case of acute fulminant rheumatic carditis in a child with no obvious predisposing factors, who resided in a developed country where this disease is not endemic. After pathological examination, a diagnosis of ARF with pancarditis was confirmed. This disease was not suspected before the pathological examination because of its low prevalence in Belgium.

Addressing rheumatic fever inequities in Aotearoa New Zealand: a scoping review of prevention interventions

Introduction Rheumatic fever is a preventable illness caused by untreated Group A Streptococcus (GAS) infection. Despite reductions in most high-income countries, rheumatic fever rates remain a concern in Aotearoa New Zealand. Pacific and Māori people are inequitably affected, with risk of initial hospitalisation due to rheumatic fever 12- and 24-fold more likely, respectively, compared to non-Māori and non-Pacific people. Aim This scoping review aims to explore the range of interventions and initiatives in New Zealand seeking to prevent GAS and rheumatic fever, with a particular focus on Pacific and Māori. Methods Databases Scopus, Medline, EMBASE and CINAHL, along with grey literature sources, were searched to broadly identify interventions in New Zealand. Data were screened for eligibility and the final articles were charted into a stocktake table. Results Fifty-eight studies were included, reporting 57 interventions. These targeted school-based throat swabbing, awareness and education, housing, secondary prophylaxis, improving primary care guidelines and diagnosis of sore throats and skin infections. Some interventions reported short-term outcomes of improvements in awareness, a reduction in rheumatic fever risk and fewer hospitalisations. Evaluation outcomes were, however, lacking for many initiatives. Pacific and Māori people primarily served only in an advisory or delivery capacity, rather than as partners in co-design or leadership from the beginning. Discussion Although positive outcomes were reported for some interventions identified in this review, rheumatic fever rates have not shown any long-term reduction over time. Co-designing interventions with affected communities could ensure that strategies are better targeted and do not contribute to further stigma.