Revising the value of Antistreptolysin O titre in childhood and its interpretation in the diagnostic approach of rheumatic diseases.

The burden of group A streptococcus (GAS) infection and its rheumatic sequelae remains dramatically high, especially in low-income countries. Recently, an increased number of Acute Rheumatic Fever (ARF) cases was documented in many regions of Italy. The diagnosis of rheumatic sequelae relies on clinical signs and on the evaluation of the Antistreptolysin O titre (ASO), whose variations are globally reported. To re-examine the standard reference value of ASO titre, by measuring either its upper limit of normal (ULN) in a population of healthy children (HC) or comparing these values with streptococcal antibodies registered in a cohort of patients affected by the rheumatic sequelae of GAS infection. We performed a multicenter retrospective study. We enrolled 125 HC, aged 2-17 years, and a total of 181 patients affected by ARF, acute streptococcal pharyngitis, post-streptococcal arthritis, Henoch-Schönlein purpura and erythema nodosum, divided into four groups. The levels of ASO and anti-deoxyribonuclease B (anti-DNase B) titres were analyzed and compared among the various groups. Moreover, the 80th percentile value was calculated and established as the ULN for ASO titre in HC group. The ULN for ASO titre in overall HC group was 515 IU/mL, resulting in higher than used in the routine investigation. The ASO titre was significantly higher in patients with rheumatic sequelae compared with HC group, with a peak in the age between 5 and 15 years.    Conclusion: Our study established a new ULN normal value of streptococcal serology in a childhood and adolescent population of Italy, suggesting the need to extend this revaluation to the critical areas, in order to avoid underestimating ARF diagnosis. The correct interpretation of ASO and anti-DNase B values in the context of rheumatic diseases has been discussed. What is Known: • The global burden of disease caused by group A streptococcus is not known and remains an important cause of morbidity and mortality. Acute rheumatic fever continues to be a serious worldwide public health problem and a recent recurrence of group A streptococcus infection cases is observed. • The streptococcal sequelae requires evidence of preceding streptococcal infection, commonly elevated streptococcal antibody titre, but the upper limit for these titres varies considerably based on age group, region, and origin. What is New: • This study provides population-specific values for streptococcal antibody titres in Italy. • Interpret the results of group A streptococcal antibody tests within the clinical context.

Current Clinical Profile of Acute Rheumatic Fever and Recurrent Acute Rheumatic Fever in Pakistan.

Inclusion of echocardiography as diagnostic tool and polyarthralgia and monoarthritis as major criteria for high-risk populations in the Revised Jones Criteria 2015 is likely to surface substantial variability in clinical manifestations among various populations. This study aimed to compare clinical profile of patients presenting with first and recurrent episodes of acute rheumatic fever (ARF) using most recent criteria. 130 consecutive patients with ARF were included in the study from August 2019 to March 2022. World Heart Federation standardized echocardiographic criteria were used for cardiac evaluation. The socio-demographic variables, clinical details and relevant investigations were recorded. Median age was 13(6-26) years. Male to female ratio was 1.6:1. Majority was of low socioeconomic status (90%) and with > 5 family members in a house (83.8%). 27 patients (20.8%) were with ARF while 103 (79.2%) with recurrent ARF. Carditis was the most common presenting feature (n = 122, 93.8%), followed by polyarthralgia (n = 46, 35.4%), polyarthritis (n = 32, 24.6%), subcutaneous nodules (n = 10, 7.7%), monoarthritis (n = 10, 7.7%), and chorea (n = 5, 3.8%). Monoarthralgia was more common in ARF than recurrence (29.4% vs. 3.2%, p = 0.004). Carditis (97.1% vs. 81.5%, p = 0.01) and congestive cardiac failure (18.5% vs. 5.9%, p = 0.001) were more common in recurrent ARF than ARF. Diagnostic categorization of Jones criteria for different populations has highlighted important variability in clinical presentation of ARF. Monoarthralgia is common in first episode of ARF. Carditis is the most common feature in recurrent ARF. Polyarthralgia is seen with higher frequency that polyarthritis. Subcutaneous nodules seem to be more common in our population.

Group A Streptococcus Infections.

Group A Streptococcus causes a variety of clinical manifestations, including pharyngitis and skin and soft tissue infections as well as more invasive disease. There are also multiple nonsuppurative complications of group A Streptococcus infection, including acute rheumatic fever and poststreptococcal glomerulonephritis. Pediatricians should be able to diagnose and treat the various presentations of the infection.

Sydenham chorea in the top end of Australia's Northern Territory: A 20-year retrospective case series.

AIM: Sydenham chorea is an immune-mediated neuropsychiatric condition, and a major criterion for diagnosis of acute rheumatic fever (ARF). Children in remote Northern Australia experience disproportionately high rates of ARF, yet studies looking at the epidemiology, clinical presentation and management of Sydenham chorea are limited in this population. METHODS: We conducted a retrospective case series from January 2002 to April 2022 of all paediatric patients aged ≤18 years admitted to Royal Darwin Hospital with Sydenham chorea. Cases were identified using the hospital's clinical coding system (ICD10). Medical records were reviewed and data on demographics, clinical presentation, investigation results, treatment and outcome were extracted, deidentified and analysed. RESULTS: One hundred ten presentations of Sydenham chorea occurred between 2002 and 2022, 109 (99%) of these were in First Nations children, with 85% residing in very remote locations. Most commonly, chorea presented as a generalised movement disorder affecting all four limbs (49%). Neuropsychiatric symptoms were reported in 33 (30%), and there was evidence of rheumatic heart disease on echocardiogram in 86 (78%) at presentation. All patients received benzathine penicillin, but there was significant variation in management of chorea, ranging from supportive management, to symptomatic management with anticonvulsants, to immunomodulatory medications including corticosteroids. CONCLUSION: This case series highlights the significant burden of Sydenham chorea among First Nations children living in Northern Australia and demonstrates wide variation in treatment approaches. High-quality clinical trials are required to determine the best treatment for this disabling condition.

Increased serum concentrations of growth differentiation factor-15 in children with acute rheumatic fever.

AIM: In this single-centre prospective study, we aimed to evaluate the role of growth differentiation factor-15 in children with acute rheumatic fever. METHODS: The study group included 25 children with acute rheumatic fever, and the control group included 25 healthy children. In addition to routine laboratory tests used in the diagnosis and treatment of acute rheumatic fever, growth differentiation factor-15 levels of the study group (at the time of diagnosis and after the treatment) and the control group were assessed and compared. RESULTS: The mean growth differentiation factor-15 level of the study group at the time of diagnosis (918.40 ± 605.65 pg/ml) was significantly higher than the mean post-treatment level (653.08 ± 330.92 pg/ml) (p = 0.015). Similarly, the mean growth differentiation factor-15 level of the study group at the time of diagnosis was significantly higher than the control group (p = 0.04). However, mean growth differentiation factor-15 levels were similar between the groups after the treatment. Growth differentiation factor-15 was positively correlated with both C-reactive protein (p < 0.001) and erythrocyte sedimentation rate (p = 0.001) at the time of diagnosis. CONCLUSION: Growth differentiation factor-15 levels are significantly increased in children with acute rheumatic fever at the time of diagnosis and return to similar levels with healthy children after treatment. Growth differentiation factor-15 is positively and significantly correlated with erythrocyte sedimentation rate and C-reactive protein at the time of diagnosis.

[Recommendations for the diagnosis and treatment of rheumatic fever in China].

Rheumatic fever is an autoimmune disease characterized by recurring acute or chronic systemic connective tissue inflammation caused by group A streptococcal infection in the throat. Although rheumatic fever is common in China, there is a lack of standardized criteria for the diagnosis and treatment of this condition. Based on evidence and guidelines from China and other countries, the Chinese Rheumatology Association developed standardized criteria for the diagnosis and treatment of this disease in China. The aim was to standardize rheumatic fever diagnosis methods, treatment opportunities, and strategies for both short-and long-term treatment, so as to reduce irreversible damage and improve prognosis.

Evaluation of an ARF diagnosis calculator: a survey and content analysis.

BACKGROUND: Acute Rheumatic Fever (ARF) is a critically important condition for which there is no diagnostic test. Diagnosis requires the use of a set of criteria comprising clinical, laboratory, electrocardiographic and echocardiographic findings. The complexity of the algorithm and the fact that clinicians lack familiarity with ARF, make ARF diagnosis ideally suited to an electronic decision support tool. The ARF Diagnosis Calculator was developed to assist clinicians in diagnosing ARF and correctly assign categories of 'possible, 'probable' or 'definite' ARF. This research aimed to evaluate the acceptability, accuracy, and test performance of the ARF Diagnosis Calculator. METHODS: Three strategies were used to provide triangulation of data. Users of the calculator employed at Top End Health Service, Northern Territory, Australia were invited to participate in an online survey, and clinicians with ARF expertise were invited to participate in semi-structured interviews. Qualitative data were analysed using inductive analysis. Performance of the calculator in correctly diagnosing ARF was assessed using clinical data from 35 patients presenting with suspected ARF. Diagnoses obtained from the calculator were compared using the Kappa statistic with those obtained from a panel of expert clinicians. RESULTS: Survey responses were available from 23 Top End Health Service medical practitioners, and interview data were available from five expert clinicians. Using a 6-point Likert scale, participants highly recommended the ARF Diagnosis Calculator (median 6, IQR 1), found it easy to use (median 5, IQR 1) and believed the calculator helped them diagnose ARF (median 5, IQR 1). Clinicians with ARF expertise noted that electronic decision making is not a substitute for clinical experience. There was high agreement between the ARF Diagnosis Calculator and the 'gold standard' ARF diagnostic process (κ = 0.767, 95% CI: 0.568-0.967). Incorrect assignment of diagnosis occurred in 4/35 (11%) patients highlighting the greater accuracy of expert clinical input for ambiguous presentations. Sixteen changes were incorporated into a revised version of the calculator. CONCLUSIONS: The ARF Diagnosis Calculator is an easy-to-use, accessible tool, but it does not replace clinical expertise. The calculator performed well amongst clinicians and is an acceptable tool for use within the clinical setting with a high level of accuracy in comparison to the gold standard diagnostic process. Effective resources to support clinicians are critically important for improving the quality of care of ARF.

Persisting burden and challenges of rheumatic heart disease.

Rheumatic heart disease (RHD) is the result of episodes of acute rheumatic fever with valvular (and other cardiac) damage caused by an abnormal immune response to group A streptococcal infections, usually during childhood and adolescence. As a result of improved living conditions and the introduction of penicillin, RHD was almost eradicated in the developed world by the 1980s. However, being a disease of poverty, its burden remains disproportionately high in the developing world, despite being a fundamentally preventable disease. Rheumatic heart disease generates relatively little attention from the medical and science communities, in contrast to other common infectious problems (such as malaria, HIV, tuberculosis), despite the major cardiovascular morbidity/mortality burden imposed by RHD. This relative neglect and paucity of funding have probably contributed to limited fundamental medical advances in this field for over 50 years. Given the importance of prevention before the onset of major valvular damage, the main challenges for RHD prevention are improving social circumstances, early diagnosis, and effective delivery of antibiotic prophylaxis. Early identification through ultrasound of silent, subclinical rheumatic valve lesions could provide an opportunity for early intervention. Simple echocardiographic diagnostic criteria and appropriately trained personnel can be valuable aids in large-scale public health efforts. In addition, a better understanding of the immunogenic determinants of the disease may provide potential routes to vaccine development and other novel therapies.

Rheumatic Heart Disease in India in 2020: Advances in Diagnostic and Therapeutic Options.

Rheumatic Fever (RF)/ Rheumatic Heart Disease (RHD) is the result of autoimmune response triggered by group A Beta-haemolytic streptococcal pharyngitis leading to immune-inflammatory injury to cardiac valves. It is practically disappeared in developed countries. However, it continues to be a major cause of disease burden among children, adolescents, and young adults in low-income countries and even in high-income countries with socioeconomic inequalities. For decades, many cases of Acute Rheumatic Fever (ARF) and RHD were missed and were denied the secondary prophylaxis, as a result these patients used to end up with complications and untimely death. Advanced understanding of the echocardiography can prevent both under diagnosis and over diagnosis and thus help in management strategy. Another new advancement in recent past is the mitral valve repair, which is technically demanding, and the results are acceptable in experienced cardiac surgical units. Whenever feasible, valve repair should be preferred over valve replacement since it precludes the need for anticoagulation and future risks of prosthesis dysfunction.

Acute Rheumatic Fever: Case Report and Literature Review.

A previously healthy 8-year-old Native American female presented with right-sided weakness and joint pain for two weeks. Following an initially unremarkable workup including negative brain and spine MRI she was noticed to have chorea and subsequently diagnosed with acute rheumatic fever (ARF). ARF is a group A streptococcus-related disease that most commonly is a sequelae of pharyngitis. The diagnosis of ARF utilizes the Jones criteria which includes heart disease, arthritis, chorea, the characteristic rash of erythema marginatum, and subcutaneous nodules. The most serious consequences of ARF include rheumatic heart disease and chorea. ARF can be treated with a combination of antibiotics and anti-inflammatories like aspirin.

Diagnosis, management, and prevention of acute rheumatic fever in the United States.

ABSTRACT: Acute rheumatic fever is a multisystem autoimmune disease caused by infection with group A streptococcus. The condition most commonly affects children ages 5 to 14 years who are from low-income populations. The diagnosis is clinical; however, the 2015 Jones Criteria can help support it. Acute rheumatic fever poses a significant health risk secondary to rheumatic heart disease. Although acute rheumatic fever is rare in the United States, outbreaks still occur, and certain populations continue to be at increased risk. This article describes how to identify acute rheumatic fever and provides prompt management and prevention strategies to reduce patient risk for lifelong complications.

The Utility of Rapid Group A Streptococcus Molecular Testing Compared with Throat Culture for the Diagnosis of Group A Streptococcal Pharyngitis in a High-Incidence Rheumatic Fever Population.

Group A streptococcus (GAS) causes significant morbidity and mortality in New Zealand and is responsible for invasive disease and immune sequelae, including acute rheumatic fever (ARF). Early treatment of GAS pharyngitis reduces the risk of ARF. In settings with a high burden of GAS disease, a rapid GAS pharyngitis diagnostic test with a strong negative predictive value is needed to enable prompt and accurate treatment. This prospective study compares the Xpert Xpress Strep A molecular test (Cepheid) to throat culture and a second molecular method, the BioGX group A streptococcus-open system reagent (OSR) for BD Max for the diagnosis of GAS pharyngitis. Throat swabs were collected from the emergency department and wards of Middlemore Hospital, New Zealand. The BioGX group A streptococcus OSR for BD Max contributes to the composite gold standard of throat culture or both molecular methods positive. Basic demographic, clinical, and laboratory data were collected. Two hundred five out of two hundred fourteen swabs were suitable for analysis. Of those, 28/205 (13.7%) were GAS culture positive, 45/205 (22%) Xpert Xpress Strep A positive, and 38/205 (18.5%) BioGX positive. Compared to culture, the sensitivity, specificity, and positive and negative predictive values of the Xpert Xpress Strep A molecular test were 100%, 90.4%, 62.2%, and 100%, respectively. Compared to the composite gold standard, the sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) were 100%, 95.8%, 84.4%, and 100%, respectively. Seventeen samples were Xpert Xpress positive but culture negative; 6 of these 17 swabs represent true positives with evidence of recent GAS infection. Ten samples were culture negative but both Xpert Xpress and BioGX positive. The Xpert Xpress Strep A molecular test is highly sensitive with a strong negative predictive value and rapid turnaround time. It can be safely introduced as a first-line test for throat swabs in a high-incidence ARF population.

Chorea as the presenting feature of acute rheumatic fever in childhood; case reports from a low-prevalence European setting.

BACKGROUND: Despite a notable decrease in acute rheumatic fever (ARF) incidence in the past few decades, there are still cases in our setting. Sydenham chorea (SC) may be the initial manifestation for this condition in childhood in a significant proportion of children. We report two cases of choreoathetosis in children as the first manifestation of ARF. CASE PRESENTATION: A previously healthy 8-year-old boy presented with right hemichorea with a predominance in the brachial region, orofacial dyskinesias and speech difficulties for the past 2 weeks. The only medical history of interest was a common catarrhal illness 3 weeks before and nonspecific bilateral tenosynovitis in both feet since a year prior. A brain computerized tomography was normal and the echocardiogram showed mild mitral and aortic regurgitation, meeting ARF criteria. He demonstrated clinical improvement with treatment based on prednisone and carbamazepine. The second patient was a 10-year-old girl with choreic movements of the right half of the body and repetitive right eye closure of 1 week duration. She had symptoms of fever and rash the previous week and pharyngitis that resolved without antibiotic 2 months before. Blood tests revealed elevated C reactive protein (12 mg/dl) and erythrocyte sedimentation rate (96 mm/h). Brain magnetic resonance was normal and echocardiogram showed left ventricle dilation and mild mitral regurgitation, leading to the diagnosis of ARF. Due to neurological involvement, she received corticosteroids and intravenous immunoglobulin treatment, with worsening of neurological symptoms that required valproic acid with remission of the hemichorea. In addition skin lessions compatible with erythema marginatum appeared on the upper limbs. CONCLUSIONS: SC should be the main diagnostic consideration in cases of hemichorea with normal neuroimaging in children. The cases reported highlight the need to maintain a high index of suspicion even in settings where incidende of ARF is low and the need to perform cardiological investigations in all patients with suspected SC, due to the possibility of subclinical valve lesions. Good adherence to secondary prophylaxis is crucial to avoid chorea relapses and worsening valve disease.

The 2020 Australian guideline for prevention, diagnosis and management of acute rheumatic fever and rheumatic heart disease.

INTRODUCTION: Acute rheumatic fever (ARF) and rheumatic heart disease (RHD) cause significant morbidity and premature mortality among Australian Aboriginal and Torres Strait Islander peoples. RHDAustralia has produced a fully updated clinical guideline in response to new knowledge gained since the 2012 edition. The guideline aligns with major international ARF and RHD practice guidelines from the American Heart Association and World Heart Federation to ensure best practice. The GRADE system was used to assess the quality and strength of evidence where appropriate. MAIN RECOMMENDATIONS: The 2020 Australian guideline details best practice care for people with or at risk of ARF and RHD. It provides up-to-date guidance on primordial, primary and secondary prevention, diagnosis and management, preconception and perinatal management of women with RHD, culturally safe practice, provision of a trained and supported Aboriginal and Torres Strait Islander workforce, disease burden, RHD screening, control programs and new technologies. CHANGES IN MANAGEMENT AS A RESULT OF THE GUIDELINE: Key changes include updating of ARF and RHD diagnostic criteria; change in secondary prophylaxis duration; improved pain management for intramuscular injections; and changes to antibiotic regimens for primary prevention. Other changes include an emphasis on provision of culturally appropriate care; updated burden of disease data using linked register and hospitalisations data; primordial prevention strategies to reduce streptococcal infection addressing household overcrowding and personal hygiene; recommendations for population-based echocardiographic screening for RHD in select populations; expanded management guidance for women with RHD or ARF to cover contraception, antenatal, delivery and postnatal care, and to stratify pregnancy risks according to RHD severity; and a priority classification system for presence and severity of RHD to align with appropriate timing of follow-up.

Incidence and clinical characteristics of acute rheumatic fever in Turkey: Results of a nationwide multicentre study.

AIM: To evaluate the incidence and clinical features of acute rheumatic fever (ARF) in Turkey, following the revised Jones criteria in 2015. METHODS: This multicentre study was designed by the Acquired Heart Diseases Working Group of the Turkish Pediatric Cardiology and Pediatric Cardiac Surgery Association in 2016. The data during the first attack of 1103 ARF patients were collected from the paediatric cardiologists between 1 January 2016 and 31 December 2016. RESULTS: Turkey National Institute of Statistics records of 2016 were used for the determination of ARF incidence with regard to various cities and regions separately. The estimated incidence rate of ARF was 8.84/100 000 in Turkey. The ARF incidence varied considerably among different regions. The highest incidence was found in the Eastern Anatolia Region as 14.4/100 000, and the lowest incidence was found in the Black Sea Region as 3.3/100 000 (P < 0.05). Clinical carditis was the most common finding. The incidence of clinical carditis, subclinical carditis, polyarthritis, aseptic monoarthritis, polyarthralgia and Sydenham's Chorea was 53.5%, 29.1%, 52.8%, 10.3%, 18.6% and 7.9%, respectively. The incidences of clinical carditis, subclinical carditis, polyarthritis and polyarthralgia were found to be significantly different among different regions (P < 0.05). CONCLUSION: The findings of this nationwide screening of ARF suggest that Turkey should be included in the moderate-risk group.

Early diagnosis of acute rheumatic fever and rheumatic heart disease as part of a secondary prevention strategy: Narrative review.

Acute rheumatic fever (ARF) and its sequela rheumatic heart disease (RHD) remain significant causes of morbidity and mortality. In New Zealand, ARF almost exclusively affects Indigenous Maori and Pacific children. This narrative review aims to present secondary interventions to improve early and accurate diagnosis of ARF and RHD, in order to minimise disease progression in New Zealand. Medline, EMBASE and Scopus databases were searched as well as other electronic publications. Included were 56 publications from 1980 onwards. Diagnosing ARF and RHD as early as possible is central to reducing disease progression. Recent identification of specific ARF biomarkers offer the opportunity to aid initial diagnosis and portable echocardiography has the potential to detect undiagnosed RHD in high-risk areas. However, further research into the benefits and risks to children with subclinical RHD is necessary, as well as an economic evaluation.

Acute Rheumatic Fever.

The incidence of acute rheumatic fever (ARF) is 8 to 51 per 100,000 people worldwide. It most commonly affects children 5 to 15 years of age after a group A streptococcal infection. Overcrowding and poor socioeconomic conditions are directly proportional to the incidence of ARF. Rheumatic carditis is a manifestation of ARF that may lead to rheumatic heart disease (RHD). Timely treatment of group A streptococcal infection can prevent ARF, and penicillin prophylaxis can prevent recurrence of ARF. Prevention of recurrent ARF is the most effective way to prevent RHD. ARF is diagnosed using the 2015 modified Jones criteria. There is no gold standard laboratory test. Therefore, clinicians need to be aware of the clinical signs and symptoms of ARF to include in their differential diagnosis when seeing such patients. Secondary prophylaxis with benzathine penicillin G has been shown to decrease the incidence of RHD and is key to RHD control. Clinicians need to understand the implications of secondary prophylaxis for ARF. There is also a need to improve ARF diagnosis, to find novel therapies to reduce the incidence of ARF, and to reduce the prevalence of RHD. RHD research is neglected and underfunded. Thus, there is also a need for RHD advocacy and public health awareness to increase research on RHD.

[NEW ONSET OF VALVULAR HEART DISEASE ALONG WITH ANCIENT PATHOLOGIC FINDING].

INTRODUCTION: Rheumatic fever (RF) is an autoinflammatory disease that is caused by the host response to an infection with group A ß-hemolytic streptococcus. In this case report we describe a 15 years old boy with Down syndrome who had unusual presentation of acute rheumatic fever with a fulminant multisystemic which included heart failure secondary to pancarditis and adult respiratory distress syndrome. The final diagnosis was confirmed after cardiac biopsy that was performed during valve replacement surgery and demonstrated Aschoff bodies - a pathognomonic finding in acute rheumatic fever.

Sydenham's Chorea with Silent Cardiac Lesions, Mimicking.

Sydenham's chorea is an uncommon neurological manifestation of rheumatic fever and has many and varied differential diagnosis. It may mimic encephalitis when presents as an isolated feature even when silent cardiac lesions are present. Early diagnosis, treatment and penicillin prophylaxis prevents recurrence and progression of cardiac lesions. Prompt symptomatic relief and alleviation of distress is obtained with therapeutic intervention. A case of rheumatic chorea with silent cardiac valve lesions which mimicked herpes simplex encephalitis with choreoathetosis, in a 13 year old girl is presented along with review of literature.

Development and Evaluation of a New Triplex Immunoassay That Detects Group A Streptococcus Antibodies for the Diagnosis of Rheumatic Fever.

Streptococcal serology is a cornerstone in the diagnosis of acute rheumatic fever (ARF), a postinfectious sequela associated with group A Streptococcus infection. Current tests that measure anti-streptolysin O (ASO) and anti-DNaseB (ADB) titers require parallel processing, with their predictive value limited by the low rate of decay in antibody response. Accordingly, our objective was to develop and assess the diagnostic potential of a triplex bead-based assay, which simultaneously quantifies ASO and ADB together with titers for a third antigen, SpnA. Our previous cytometric bead assay was transferred to the clinically appropriate Luminex platform by coupling streptolysin O, DNaseB, and SpnA to spectrally unique magnetic beads. Sera from more than 350 subjects, including 97 ARF patients, were used to validate the assay and explore immunokinetics. Operating parameters demonstrate that the triplex assay produces accurate and reproducible antibody titers which, for ASO and ADB, are highly correlative with existing assay methodology. When ARF patients were stratified by time (days following hospital admission), there was no difference in ASO and ADB between <28 and 28+ day groups. However, for anti-SpnA, there was a significant decrease (P < 0.05) in the 28+ day group, indicative of faster anti-SpnA antibody decay. Anti-SpnA immunokinetics support very recent group A Streptococcus infection and may assist in diagnostic classification of ARF. Further, bead-based assays enable streptococcal serology to be performed efficiently in a high-throughput manner.