Low rates of streptococcal pharyngitis and high rates of pyoderma in Australian aboriginal communities where acute rheumatic fever is hyperendemic

Streptococcus dysgalactiae subsp. equisimilis infection and its intersection with Streptococcus pyogenes

SUMMARYStreptococcus dysgalactiae subsp. equisimilis (SDSE) is an increasingly recognized cause of disease in humans. Disease manifestations range from non-invasive superficial skin and soft tissue infections to life-threatening streptococcal toxic shock syndrome and necrotizing fasciitis. Invasive disease is usually associated with co-morbidities, immunosuppression, and advancing age. The crude incidence of invasive disease approaches that of the closely related pathogen, Streptococcus pyogenes. Genomic epidemiology using whole-genome sequencing has revealed important insights into global SDSE population dynamics including emerging lineages and spread of anti-microbial resistance. It has also complemented observations of overlapping pathobiology between SDSE and S. pyogenes, including shared virulence factors and mobile gene content, potentially underlying shared pathogen phenotypes. This review provides an overview of the clinical and genomic epidemiology, disease manifestations, treatment, and virulence determinants of human infections with SDSE with a particular focus on its overlap with S. pyogenes. In doing so, we highlight the importance of understanding the overlap of SDSE and S. pyogenes to inform surveillance and disease control strategies.

Tonsils at Telethon: developing a standardised collection of tonsil photographs for group A streptococcal (GAS) research

Introduction

Group A streptococcus (GAS) infections, such as pharyngitis and impetigo, can lead to rheumatic fever and rheumatic heart disease (RHD). Australian Aboriginal and Torres Strait Islander populations experience high rates of RHD and GAS skin infection, yet rates of GAS pharyngitis are unclear. Anecdotally, clinical presentations of pharyngitis, including tonsillar hypertrophy and sore throat, are uncommon. This study aimed to develop a standardised set of tonsil photographs and determine tonsil size distribution from an urban paediatric population.

Methods

A prospective cohort of children aged 3-15 years were recruited at the public events "Discover Day" and "Telethon Weekend" (October 2017) in Perth, Western Australia, Australia. Tonsil photographs, symptomatology, and GAS rapid antigen detection tests (RADT) were collected. Tonsil size was graded from the photographs using the Brodsky Grading Scale of tonsillar hypertrophy (Brodsky) by two independent clinicians, and inter-rater reliability calculated. Pharyngitis symptoms and GAS RADT were correlated, and immediate results provided.

Results

Four hundred and twenty-six healthy children participated in the study over three days. The median age was seven years [interquartile range (IQR) 5.9-9.7 years]. Tonsil photographs were collected for 92% of participants, of which 62% were rated as good-quality photographs and 79% were deemed of adequate quality for assessment by both clinicians. When scored by two independent clinicians, 57% received the same grade. Average Brodsky grades (between clinicians) were 11%, 35%, 28%, 22% and 5% of grades 0,1,2,3 and 4, respectively. There was moderate agreement in grading using photographs, and minimal to weak agreement for signs of infection. Of 394 participants, 8% reported a sore throat. Of 334 GAS RADT performed, <1% were positive.

Discussion

We report the first standardised use of paediatric tonsil photographs to assess tonsil size in urban-living Australian children. This provides a proof of concept from an urban-living cohort that could be compared with children in other settings with high risk of GAS pharyngitis or rheumatic fever such as remote-living Australian Indigenous populations.

Overlapping Streptococcus pyogenes and Streptococcus dysgalactiae subspecies equisimilis household transmission and mobile genetic element exchange

Streptococcus dysgalactiae subspecies equisimilis (SDSE) and Streptococcus pyogenes share skin and throat niches with extensive genomic homology and horizontal gene transfer (HGT) possibly underlying shared disease phenotypes. It is unknown if cross-species transmission interaction occurs. Here, we conduct a genomic analysis of a longitudinal household survey in remote Australian First Nations communities for patterns of cross-species transmission interaction and HGT. Collected from 4547 person-consultations, we analyse 294 SDSE and 315 S. pyogenes genomes. We find SDSE and S. pyogenes transmission intersects extensively among households and show that patterns of co-occurrence and transmission links are consistent with independent transmission without inter-species interference. We identify at least one of three near-identical cross-species mobile genetic elements (MGEs) carrying antimicrobial resistance or streptodornase virulence genes in 55 (19%) SDSE and 23 (7%) S. pyogenes isolates. These findings demonstrate co-circulation of both pathogens and HGT in communities with a high burden of streptococcal disease, supporting a need to integrate SDSE and S. pyogenes surveillance and control efforts.

Disruption of IL-17-mediated immunosurveillance in the respiratory mucosa results in invasive Streptococcus pyogenes infection

Introduction

Streptococcus pyogenes is a Gram-positive pathogen that causes a significant global burden of skin pyoderma and pharyngitis. In some cases, infection can lead to severe invasive streptococcal diseases. Previous studies have shown that IL-17 deficiency in mice (IL-17-/-) can reduce S. pyogenes clearance from the mucosal surfaces. However, the effect of IL-17 on the development of severe invasive streptococcal disease has not yet been assessed.

Methods

Here, we modeled single or repeated non-lethal intranasal (IN) S. pyogenes M1 strain infections in immunocompetent and IL-17-/- mice to assess bacterial colonization following a final IN or skin challenge.

Results

Immunocompetent mice that received a single S. pyogenes infection showed long-lasting immunity to subsequent IN infection, and no bacteria were detected in the lymph nodes or spleens. However, in the absence of IL-17, a single IN infection resulted in dissemination of S. pyogenes to the lymphoid organs, which was accentuated by repeated IN infections. In contrast to what was observed in the respiratory mucosa, skin immunity did not correlate with the systemic levels of IL-17. Instead, it was found to be associated with the activation of germinal center responses and accumulation of neutrophils in the spleen.

Discussion

Our results demonstrated that IL-17 plays a critical role in preventing invasive disease following S. pyogenes infection of the respiratory tract.

Application of Transthoracic Echocardiography for Cardiac Safety Evaluation in the Clinical Development Process of Vaccines Against Streptococcus pyogenes

Superficial infections with Streptococcus pyogenes (Strep A), pharyngitis and impetigo can induce acute rheumatic fever, an autoimmune sequela manifesting mostly with arthritis and rheumatic carditis. Valvular heart damage can persist or advance following repeated episodes of acute rheumatic fever, causing rheumatic heart disease. Acute rheumatic fever and rheumatic heart disease disproportionately affect children and young adults in developing countries and disadvantaged communities in developed countries. People living with rheumatic heart disease are at risk of experiencing potentially fatal complications such as heart failure, bacterial endocarditis or stroke. Transthoracic echocardiography plays a central role in diagnosing both rheumatic carditis and rheumatic heart disease. Despite the obvious medical need, no licensed Strep A vaccines are currently available, as their clinical development process faces several challenges, including concerns for cardiac safety. However, the development of Strep A vaccines has been recently relaunched by many vaccine developers. In this context, a reliable and consistent safety evaluation of Strep A vaccine candidates, including the use of transthoracic echocardiography for detecting cardiac adverse events, could greatly contribute to developing a safe and efficacious product in the near future. Here, we propose a framework for the consistent use of transthoracic echocardiography to proactively detect cardiac safety events in clinical trials of Strep A vaccine candidates.

The epidemiology of superficial Streptococcal A (impetigo and pharyngitis) infections in Australia: A systematic review

BACKGROUND

Streptoccocal A (Strep A, GAS) infections in Australia are responsible for significant morbidity and mortality through both invasive (iGAS) and post-streptococcal (postGAS) diseases as well as preceding superficial (sGAS) skin and throat infection. The burden of iGAS and postGAS are addressed in some jurisdictions by mandatory notification systems; in contrast, the burden of preceding sGAS has no reporting structure, and is less well defined. This review provides valuable, contemporaneous evidence on the epidemiology of sGAS presentations in Australia, informing preventative health projects such as a Streptococcal A vaccine and standardisation of primary care notification.

METHODS AND FINDINGS

MEDLINE, Scopus, EMBASE, Web of Science, Global Health, Cochrane, CINAHL databases and the grey literature were searched for studies from an Australian setting relating to the epidemiology of sGAS infections between 1970 and 2020 inclusive. Extracted data were pooled for relevant population and subgroup analysis. From 5157 titles in the databases combined with 186 grey literature reports and following removal of duplicates, 4889 articles underwent preliminary title screening. The abstract of 519 articles were reviewed with 162 articles identified for full text review, and 38 articles identified for inclusion. The majority of data was collected for impetigo in Aboriginal and Torres Strait Islander populations, remote communities, and in the Northern Territory, Australia. A paucity of data was noted for Aboriginal and Torres Strait Islander people living in urban centres or with pharyngitis. Prevalence estimates have not significantly changed over time. Community estimates of impetigo point prevalence ranged from 5.5-66.1%, with a pooled prevalence of 27.9% [95% CI: 20.0-36.5%]. All studies excepting one included >80% Aboriginal and Torres Strait Islander people and all excepting two were in remote or very remote settings. Observed prevalence of impetigo as diagnosed in healthcare encounters was lower, with a pooled estimate of 10.6% [95% CI: 3.1-21.8%], and a range of 0.1-50.0%. Community prevalence estimates for pharyngitis ranged from 0.2-39.4%, with a pooled estimate of 12.5% [95% CI: 3.5-25.9%], higher than the prevalence of pharyngitis in healthcare encounters; ranging from 1.0-5.0%, and a pooled estimate of 2.0% [95% CI: 1.3-2.8%]. The review was limited by heterogeneity in study design and lack of comparator studies for some populations.

CONCLUSIONS

Superficial Streptococcal A infections contribute to an inequitable burden of disease in Australia and persists despite public health interventions. The burden in community studies is generally higher than in health-services settings, suggesting under-recognition, possible normalisation and missed opportunities for treatment to prevent postGAS. The available, reported epidemiology is heterogeneous. Standardised nation-wide notification for sGAS disease surveillance must be considered in combination with the development of a Communicable Diseases Network of Australia (CDNA) Series of National Guideline (SoNG), to accurately define and address disease burden across populations in Australia.

TRIAL REGISTRATION

This review is registered with PROSPERO. Registration number: CRD42019140440.

Rheumatic Heart Disease in the Developing World

Despite recent public policy initiatives, rheumatic heart disease (RHD) remains a major source of morbidity worldwide. Rheumatic heart disease occurs as a sequela of Streptococcus pyogenes (group A streptococcal [GAS]) infection in patients with genetic susceptibility. Strategies for prevention of RHD or progression of RHD include prevention of GAS infection with community initiatives, effective treatment of GAS infection, and secondary prophylaxis with intramuscular penicillin. The cardiac surgical community has attempted to improve the availability of surgery in RHD-endemic areas with some success, and operative techniques and outcomes of valve repair continue to improve, potentially offering patients a safer, more durable operation. Innovation offers hope for a more scalable solution with improved biomaterials and transcatheter delivery technology; however, cost remains a barrier.

Streptococcus pyogenes carriage acquisition, persistence and transmission dynamics within households in The Gambia (SpyCATS): protocol for a longitudinal household cohort study

Background

Streptococcus pyogenes (StrepA) causes a significant burden of disease globally from superficial infections to invasive disease. It is responsible for over 500,000 deaths each year, predominantly in low- and middle-income countries (LMIC). Superficial StrepA infections of the skin and pharynx can lead to rheumatic heart disease, the largest cause of StrepA-related deaths in LMIC. StrepA can also asymptomatically colonise normal skin and the pharynx (carriage), potentially increasing infection risk. Streptococcus dysgalactiae subsp. equisimilis (SDSE) carriage is also common in LMIC and may interact with StrepA. This study aims to investigate StrepA and SDSE carriage and infection epidemiology, transmission dynamics and naturally acquired immunity within households in The Gambia.

Methods

A longitudinal household observational cohort study will be conducted over one year. 45 households will be recruited from the urban area of Sukuta, The Gambia, resulting in approximately 450 participants. Households will be visited monthly, and available participants will undergo oropharyngeal and normal skin swabbing. Incident cases of pharyngitis and pyoderma will be captured via active case reporting, with swabs taken from disease sites. Swabs will be cultured for the presence of group A, C and G beta-haemolytic streptococci. Isolates will undergo whole genome sequencing. At each visit, clinical, socio-demographic and social mixing data will be collected. Blood serum will be collected at baseline and final visit. Oral fluid and dried blood spot samples will be collected at each visit. Mucosal and serum anti-StrepA antibody responses will be measured.

Outcome

This study will report StrepA and SDSE clinical epidemiology, risk factors, transmission dynamics, and serological responses to carriage and infection. Detailed social mixing behaviour will be combined with phylogenetic relatedness to model the extent of transmission occurring withing and between households. The study will provide data to help meet global strategic StrepA research goals.

Research opportunities for the primary prevention and management of acute rheumatic fever and rheumatic heart disease: a National Heart, Lung, and Blood Institute workshop report

Primary prevention of acute rheumatic fever (ARF) and rheumatic heart disease (RHD) encompasses the timely diagnosis and adequate treatment of the superficial group A Streptococcus (GAS) infections pharyngitis and impetigo. GAS is the only known inciting agent in the pathophysiology of the disease. However, sufficient evidence indicates that the uptake and delivery of primary prevention approaches in RHD-endemic regions are significantly suboptimal. This report presents expert deliberations on priority research and implementation opportunities for primary prevention of ARF/RHD that were developed as part of a workshop convened by the US National Heart, Lung, and Blood Institute in November 2021. The opportunities identified by the Primary Prevention Working Group encompass epidemiological, laboratory, clinical, implementation and dissemination research domains and are anchored on five pillars including: (A) to gain a better understanding of superficial GAS infection epidemiology to guide programmes and policies; (B) to improve diagnosis of superficial GAS infections in RHD endemic settings; (C) to develop scalable and sustainable models for delivery of primary prevention; (D) to understand potential downstream effects of the scale-up of primary prevention and (E) to develop and conduct economic evaluations of primary prevention strategies in RHD endemic settings. In view of the multisectoral stakeholders in primary prevention strategies, we emphasise the need for community co-design and government engagement, especially in the implementation and dissemination research arena. We present these opportunities as a reference point for research organisations and sponsors who aim to contribute to the increasing momentum towards the global control and prevention of RHD.

An outbreak of acute rheumatic fever in a remote Aboriginal community

OBJECTIVES

We describe the public health response to an outbreak of acute rheumatic fever (ARF) in a remote Aboriginal community.

METHODS

In August 2021, the Northern Territory Rheumatic Heart Disease Control Program identified an outbreak of acute rheumatic fever in a remote Aboriginal community. A public health response was developed using a modified acute poststreptococcal glomerulonephritis protocol and the National Acute Rheumatic Fever Guideline for Public Health Units.

RESULTS

12 cases were diagnosed during the outbreak; six-times the average number of cases in the same period in the five years prior (n=1.8). Half (n=6) of the outbreak cases were classified as recurrent episodes with overdue secondary prophylaxis. Contact tracing and screening of 11 households identified 86 close contacts.

CONCLUSIONS

This outbreak represented an increase in both first episodes and recurrences of acute rheumatic fever and highlights the critical need for strengthened delivery of acute rheumatic fever secondary prophylaxis, and for improvements to the social determinants of health in the region.

IMPLICATIONS FOR PUBLIC HEALTH

Outbreaks of acute rheumatic fever are rare despite continuing high rates of acute rheumatic fever experienced by remote Aboriginal communities. Nevertheless, there can be improvements in the current national public health guidance relating to acute rheumatic fever cluster and outbreak management.

Evaluating the role of asymptomatic throat carriage of Streptococcus pyogenes in impetigo transmission in remote Aboriginal communities in Northern Territory, Australia: a retrospective genomic analysis

BACKGROUND

Streptococcus pyogenes, or group A Streptococcus (GAS), infections contribute to a high burden of disease in Aboriginal Australians, causing skin infections and immune sequelae such as rheumatic heart disease. Controlling skin infections in these populations has proven difficult, with transmission dynamics being poorly understood. We aimed to identify the relative contributions of impetigo and asymptomatic throat carriage to GAS transmission.

METHODS

In this genomic analysis, we retrospectively applied whole genome sequencing to GAS isolates that were collected as part of an impetigo surveillance longitudinal household survey conducted in three remote Aboriginal communities in the Northern Territory of Australia between Aug 6, 2003, and June 22, 2005. We included GAS isolates from all throats and impetigo lesions of people living in two of the previously studied communities. We classified isolates into genomic lineages based on pairwise shared core genomes of more than 99% with five or fewer single nucleotide polymorphisms. We used a household network analysis of epidemiologically and genomically linked lineages to quantify the transmission of GAS within and between households.

FINDINGS

We included 320 GAS isolates in our analysis: 203 (63%) from asymptomatic throat swabs and 117 (37%) from impetigo lesions. Among 64 genomic lineages (encompassing 39 emm types) we identified 264 transmission links (involving 93% of isolates), for which the probable source was asymptomatic throat carriage in 166 (63%) and impetigo lesions in 98 (37%). Links originating from impetigo cases were more frequent between households than within households. Households were infected with GAS for a mean of 57 days (SD 39 days), and once cleared, reinfected 62 days (SD 40 days) later. Increased household size and community presence of GAS and scabies were associated with slower clearance of GAS.

INTERPRETATION

In communities with high prevalence of endemic GAS-associated skin infection, asymptomatic throat carriage is a GAS reservoir. Public health interventions such as vaccination or community infection control programmes aimed at interrupting transmission of GAS might need to include consideration of asymptomatic throat carriage.

FUNDING

Australian National Health and Medical Research Council.

Streptococcus pyogenes carriage acquisition, persistence and transmission dynamics within households in The Gambia (SpyCATS): protocol for a longitudinal household cohort study

Background Streptococcus pyogenes (StrepA) causes a significant burden of disease globally from superficial infections to invasive disease. It is responsible for over 500,000 deaths each year, predominantly in low- and middle-income countries (LMIC). Superficial StrepA infections of the skin and pharynx can lead to rheumatic heart disease, the largest cause of StrepA-related deaths in LMIC. StrepA can also asymptomatically colonise normal skin and the pharynx (carriage), potentially increasing infection risk. Streptococcus dysgalactiae subsp. equisimilis (SDSE) carriage is also common in LMIC and may interact with StrepA. This study aims to investigate StrepA and SDSE carriage and infection epidemiology, transmission dynamics and naturally acquired immunity within households in The Gambia. Methods A longitudinal household observational cohort study will be conducted over one year. 45 households will be recruited from the urban area of Sukuta, The Gambia, resulting in approximately 450 participants. Households will be visited monthly, and available participants will undergo oropharyngeal and normal skin swabbing. Incident cases of pharyngitis and pyoderma will be captured via active case reporting, with swabs taken from disease sites. Swabs will be cultured for the presence of group A, C and G beta-haemolytic streptococci. Isolates will undergo whole genome sequencing. At each visit, clinical, socio-demographic and social mixing data will be collected. Blood serum will be collected at baseline and final visit. Oral fluid and dried blood spot samples will be collected at each visit. Mucosal and serum anti-StrepA antibody responses will be measured. Outcome This study will report StrepA and SDSE clinical epidemiology, risk factors, transmission dynamics, and serological responses to carriage and infection. Detailed social mixing behaviour will be combined with phylogenetic relatedness to model the extent of transmission occurring withing and between households. The study will provide data to help meet global strategic StrepA research goals.

Rheumatic Heart Disease: JACC Focus Seminar 2/4

It is a sad reality that although eminently preventable, and despite possessing such knowledge for >70 years, rheumatic heart disease (RHD) remains the most common cause of cardiovascular morbidity and early mortality in young people worldwide. A disease of the poor, RHD is one of the most neglected diseases. Several challenges are unique to the acute rheumatic fever/RHD continuum and contribute to its persistence, including its sequestration among the poorest, its protracted natural history, the erratic availability of penicillin, and the lack of a concerted effort in endemic regions. However, there is cause for optimism following a resurgence in scientific interest over the last 15 years. This review presents the latest advancements in epidemiology, diagnosis, and management. It also discusses pressing research questions on disease pathophysiology, the barriers to implementation of effective management strategies, and pragmatic policy solutions required for translation of current knowledge into meaningful action.

A pilot study to develop assessment tools for Group A Streptococcus surveillance studies

Introduction

Group A Streptococcus (GAS) causes pharyngitis (sore throat) and impetigo (skin sores) GAS pharyngitis triggers rheumatic fever (RF) with epidemiological evidence supporting that GAS impetigo may also trigger RF in Australian Aboriginal children. Understanding the concurrent burden of these superficial GAS infections is critical to RF prevention. This pilot study aimed to trial tools for concurrent surveillance of sore throats and skins sore for contemporary studies of RF pathogenesis including development of a sore throat checklist for Aboriginal families and pharynx photography.

Methods

Yarning circle conversations and semi-structured interviews were performed with Aboriginal caregivers and used to develop the language and composition of a sore throat checklist. The sore throat story checklist was combined with established methods of GAS pharyngitis and impetigo surveillance (examination, bacteriological culture, rapid antigen detection and serological tests) and new technologies (photography) and used for a pilot cross-sectional surveillance study of Aboriginal children attending their health clinic for a routine appointment. Feasibility, acceptability, and study costs were compiled.

Results

Ten Aboriginal caregivers participated in the sore-throat yarning circles; a checklist was derived from predominant symptoms and their common descriptors. Over two days, 21 Aboriginal children were approached for the pilot surveillance study, of whom 17 were recruited; median age was 9 years [IQR 5.5-13.5], 65% were female. One child declined throat swabbing and three declined finger pricks; all other surveillance elements were completed by each child indicating high acceptability of surveillance assessments. Mean time for screening assessment was 19 minutes per child. Transport of clinical specimens enabled gold standard microbiological and serological testing for GAS. Retrospective examination of sore throat photography concorded with assessments performed on the day.

Conclusion

Yarning circle conversations were effective in deriving culturally appropriate sore throat questionnaires for GAS pharyngitis surveillance. New and established tools were feasible, practical and acceptable to participants and enable surveillance to determine the burden of superficial GAS infections in communities at high risk of RF. Surveillance of GAS pharyngitis and impetgio in remote Australia informs primary RF prevention with potential global translation.

Standardization of Epidemiological Surveillance of Group A Streptococcal Impetigo

Impetigo is a highly contagious bacterial infection of the superficial layer of skin. Impetigo is caused by group A Streptococcus (Strep A) and Staphylococcus aureus, alone or in combination, with the former predominating in many tropical climates. Strep A impetigo occurs mainly in early childhood, and the burden varies worldwide. It is an acute, self-limited disease, but many children experience frequent recurrences that make it a chronic illness in some endemic settings. We present a standardized surveillance protocol including case definitions for impetigo including both active (purulent, crusted) and resolving (flat, dry) phases and discuss the current tests used to detect Strep A among persons with impetigo. Case classifications that can be applied are detailed, including differentiating between incident (new) and prevalent (existing) cases of Strep A impetigo. The type of surveillance methodology depends on the burden of impetigo in the community. Active surveillance and laboratory confirmation is the preferred method for case detection, particularly in endemic settings. Participant eligibility, surveillance population and additional considerations for surveillance of impetigo, including examination of lesions, use of photographs to document lesions, and staff training requirements (including cultural awareness), are addressed. Finally, the core elements of case report forms for impetigo are presented and guidance for recording the course and severity of impetigo provided.

Scabies incidence and association with skin and soft tissue infection in Loyalty Islands Province, New Caledonia: A 15-year retrospective observational study using electronic health records

Background

Scabies and its complications are a public health problem in the low- and middle-income countries of the Western Pacific region. However, no data are available for the relatively wealthy French territory of New Caledonia. This study aimed to determine the incidence of scabies and its association with skin and soft tissue infection (SSTI) in Loyalty Islands Province (LIP) (20,000 inhabitants), New Caledonia.

Methodology/Principal findings

This retrospective observational study reviewed cases of scabies and SSTI extracted from the electronic health record databases of LIP clinics for the period 2004–2018. Data were validated through double sampling. The overall scabies incidence rate (IR) and scabies IRs by sex and age group were calculated. Scabies seasonality was evaluated. For children <5 years, the presence of SSTI was compared between the 3-month period preceding scabies diagnosis/treatment and the 3-month period preceding the 1-year anniversary of scabies diagnosis/treatment (self-matching).

A total of 16,843 scabies cases were extracted using a detection algorithm with a sensitivity of 96.7% and a specificity of 99.9%. From 2004 to 2018, the average overall scabies IR was 5.9% and the average scabies IR in children <1 year was 18.4%. Almost two-thirds of children aged 14 years had a history of scabies. Females were more affected, especially in the 20–39 age group (sex ratio>2). A strong seasonality was observed, with a 30% increase in winter. In children <5 years, SSTIs were 4.3 times more frequent in the 3 months preceding the scabies diagnosis than in the 3 months preceding the 1-year anniversary of scabies treatment (p<0.001).

Conclusions

Although health care is much better in New Caledonia than in neighboring countries, scabies is highly endemic in LIP. The disease is especially common in children <2 years and is associated with many SSTIs in children <5 years. Mass drug administration should be considered.

Scabies is a known public health problem in the Pacific region. This study aimed to determine the importance of scabies and associated skin infections in the Loyalty Island Province (LIP) of New Caledonia (20,000 inhabitants).

The provincial electronic medical database was searched for all cases of scabies and skin infection that occurred in the LIP population between 2004 and 2018. To evaluate the impact of scabies on skin infections, we measured the decrease in the number of skin infections in children <5 years one year after scabies treatment.

Over the study period, the average number of scabies cases occurring each year was 6 per 100 inhabitants. In children <1 year, this number was 18 per 100 inhabitants. We found that 80% of children aged 15 years had experienced at least one episode of scabies. We also observed a fourfold decrease in the number of skin infections in children <5 years 1 year after treatment. Scabies was more frequent (+30%) in winter.

Population pharmacokinetic study of benzathine penicillin G administration in Indigenous children and young adults with rheumatic heart disease in the Northern Territory, Australia

BACKGROUND

Benzathine penicillin G (BPG) is the cornerstone of secondary prophylaxis to prevent Streptococcus pyogenes infections, which precede acute rheumatic fever (ARF). The paucity of pharmacokinetic (PK) data from children and adolescents from populations at the highest risk of ARF and rheumatic heart disease (RHD) poses a challenge for determining the optimal dosing and frequency of injections and undermines efforts to develop improved regimens.

METHODS

We conducted a 6 month longitudinal PK study of young people receiving BPG for secondary prophylaxis. Throat and skin swabs were collected for microbiological culture along with dried blood spot (DBS) samples for penicillin concentrations. DBSs were assayed using LC-MS/MS. Penicillin concentration datasets were analysed using non-linear mixed-effects modelling and simulations performed using published BMI-for-age and weight-for-age data.

RESULTS

Nineteen participants provided 75 throat swabs, 3 skin swabs and 216 penicillin samples. Throat cultures grew group C and G Streptococcus. Despite no participant maintaining penicillin concentration >20 ng/mL between doses, there were no S. pyogenes throat infections and no ARF. The median (range) observed durations >20 ng/mL for the low- and high-BMI groups were 14.5 (11.0-24.25) and 15.0 (7.5-18.25) days, respectively.

CONCLUSIONS

Few patients at highest risk of ARF/RHD receiving BPG for secondary prophylaxis maintain penicillin concentrations above the target of 20 ng/mL beyond 2 weeks during each monthly dosing interval. These PK data suggest that some high-risk individuals may get inadequate protection from every 4 week dosing. Future research should explore this gap in knowledge and PK differences between different populations to inform future dosing schedules.

The global burden of sore throat and group A Streptococcus pharyngitis: A systematic review and meta-analysis

BACKGROUND

Contemporary data for the global burden of sore throat and group A Streptococcus (Strep A) pharyngitis are required to understand the frequency of disease and develop value propositions for Strep A vaccines.

METHODS

We used Clarivate Analytics' Web of Science platform to search WoS core collection, PubMed, Medline, data citation index, KCI-Korean Journal Database, Russian Science Citation Index, and the SciELO Citation Index for articles published between Jan 1, 2000, and Feb 15, 2021, from any country and in any language. The risk of bias was assessed using the JBI critical appraisal checklist. We used random-effects meta-analyses to pool sore throat and Strep A sore throat incidence rates from community-based studies. Our study was registered with PROSPERO (CRD42020181103).

FINDINGS

Of 5,529 articles identified by the search strategy, 26 studies met the inclusion criteria, but only two included data to determine incidence among adults. The pooled incidence rate, calculated for children only, was 82.2 episodes per 100 child-years (95% CI 25.2-286.3, I² = 100%) for sore throat (7 studies; 7,964 person years) and 22.1 episodes per 100 child-years (95% CI 14.7-33.1, I² = 98%) for Strep A sore throat (9 studies; 15,696 person years). The pooled cumulative incidence rate of sore throat from five studies was 31.9 per 100 children. There was significant methodological and statistical heterogeneity among studies, and five of 26 studies had a risk of bias score less than five (range: nine [maximum score] to one).

INTERPRETATION

Strep A sore throat has a considerable global burden. However, methodologically standardised studies are required to quantify that burden, analyse differences in rates between populations, and evaluate the likely impact of future Strep A vaccines.

FUNDING

This study was funded by Wellcome Trust 215,490/Z/19/Z.

Missing Piece Study protocol: prospective surveillance to determine the epidemiology of group A streptococcal pharyngitis and impetigo in remote Western Australia

INTRODUCTION

Group A β-haemolytic Streptococcus (GAS), a Gram-positive bacterium, causes skin, mucosal and systemic infections. Repeated GAS infections can lead to autoimmune diseases acute rheumatic fever (ARF) and rheumatic heart disease (RHD). Aboriginal and Torres Strait Islander peoples in Australia have the highest rates of ARF and RHD in the world. Despite this, the contemporaneous prevalence and incidence of GAS pharyngitis and impetigo in remote Australia remains unknown. To address this, we have designed a prospective surveillance study of GAS pharyngitis and impetigo to collect coincident contemporary evidence to inform and enhance primary prevention strategies for ARF.

METHODS AND ANALYSIS

The Missing Piece Study aims to document the epidemiology of GAS pharyngitis and impetigo through collection of clinical, serological, microbiological and bacterial genomic data among remote-living Australian children. The study comprises two components: (1) screening of all children at school for GAS pharyngitis and impetigo up to three times a year and (2) weekly active surveillance visits to detect new cases of pharyngitis and impetigo. Environmental swabbing in remote schools will be included, to inform environmental health interventions. In addition, the application of new diagnostic technologies, microbiome analysis and bacterial genomic evaluations will enhance primary prevention strategies, having direct bearing on clinical care, vaccine development and surveillance for vaccine clinical trials.

ETHICS AND DISSEMINATION

Ethical approval has been obtained from the Western Australian Aboriginal Health Ethics Committee (Ref: 892) and Human Research Ethics Committee of the University of Western Australia (Ref: RA/4/20/5101). Study findings will be shared with community members, teachers and children at participating schools, together with academic and medical services. Sharing findings in an appropriate manner is important and will be done in a suitable way which includes plain language summaries and presentations. Finally, findings and updates will also be disseminated to collaborators, researchers and health planners through peer-reviewed journal publications.

OUP accepted manuscript

Background

Group A Streptococcus (GAS) causes superficial pharyngitis and skin infections as well as serious autoimmune sequelae such as acute rheumatic fever (ARF) and subsequent rheumatic heart disease. ARF pathogenesis remains poorly understood. Immune priming by repeated GAS infections is thought to trigger ARF, and there is growing evidence for the role of skin infections in this process.

Methods

We utilized our recently developed 8-plex immunoassay, comprising antigens used in clinical serology for diagnosis of ARF (SLO, DNase B, SpnA), and 5 conserved putative GAS vaccine antigens (Spy0843, SCPA, SpyCEP, SpyAD, Group A carbohydrate), to characterize antibody responses in sera from New Zealand children with a range of clinically diagnosed GAS disease: ARF (n = 79), GAS-positive pharyngitis (n = 94), GAS-positive skin infection (n = 51), and matched healthy controls (n = 90).

Results

The magnitude and breadth of antibodies in ARF was very high, giving rise to a distinct serological profile. An average of 6.5 antigen-specific reactivities per individual was observed in ARF, compared to 4.2 in skin infections and 3.3 in pharyngitis.

Conclusions

ARF patients have a unique serological profile, which may be the result of repeated precursor pharyngitis and skin infections that progressively boost antibody breadth and magnitude.

Protocol for the systematic review of the epidemiology of superficial Streptococcal A infections (skin and throat) in Australia

OBJECTIVE

We have produced a protocol for the comprehensive systematic review of the current literature around superficial group A Streptococcal infections in Australia.

METHODS

MEDLINE, Scopus, EMBASE, Web of Science, Global Health, Cochrane, CINAHL databases and the gray literature will be methodically and thoroughly searched for studies relating to the epidemiology of superficial group A Streptococcal infections between the years 1970 and 2019. Data will be extracted to present in the follow up systematic review.

CONCLUSION

A rigorous and well-organised search of the current literature will be performed to determine the current and evolving epidemiology of superficial group A Streptococcal infections in Australia.

Formative evaluation of a community-based approach to reduce the incidence of Strep A infections and acute rheumatic fever

OBJECTIVES

To explore the acceptability of a novel, outreached-based approach to improve primary and primordial prevention of Strep A skin sores, sore throats and acute rheumatic fever in remote Aboriginal communities.

METHODS

A comprehensive prevention program delivered by trained Aboriginal Community Workers was evaluated using approximately fortnightly household surveys about health and housing and clinical records.

RESULTS

Twenty-seven primary participants from three remote Aboriginal communities in the Northern Territory consented, providing 37.8 years of retrospective baseline data and 18.5 years of prospective data during the study period. Household members were considered to be secondary participants. Five Aboriginal Community Workers were trained and employed, delivering a range of supports to households affected by acute rheumatic fever including environmental health support and education. Clinical record audit and household self-report of Strep A infections were compared. No association between clinical- and self-report was identified.

CONCLUSIONS

Ongoing participation suggests this outreach-based prevention program was acceptable and associated with improved reporting of household maintenance issues and awareness of prevention opportunities for Strep A infections. Implications for public health: Biomedical, clinic-based approaches to the management of Strep A infections in remote communities can be usefully augmented by outreach-based supports delivered by Aboriginal Community Workers responding to community needs.

In Search of the Holy Grail: A Specific Diagnostic Test for Rheumatic Fever

Current diagnosis of Acute Rheumatic Fever and Rheumatic Heart Disease (ARF/RHD) relies on a battery of clinical observations aided by technologically advanced diagnostic tools and non-specific laboratory tests. The laboratory-based assays fall into two categories: those that (1) detect "evidence of preceding streptococcal infections" (ASOT, anti-DNAse B, isolation of the Group A Streptococcus from a throat swab) and (2) those that detect an ongoing inflammatory process (ESR and CRP). These laboratory tests are positive during any streptococcal infection and are non-specific for the diagnosis of ARF/RHD. Over the last few decades, we have accumulated considerable knowledge about streptococcal biology and the immunopathological mechanisms that contribute to the development, progression and exacerbation of ARF/RHD. Although our knowledge is incomplete and many more years will be devoted to understanding the exact molecular and cellular mechanisms involved in the spectrum of clinical manifestations of ARF/RHD, in this commentary we contend that there is sufficient understanding of the disease process that using currently available technologies it is possible to identify pathogen associated peptides and develop a specific test for ARF/RHD. It is our view that with collaboration and sharing of well-characterised serial blood samples from patients with ARF/RHD from different regions, antibody array technology and/or T-cell tetramers could be used to identify streptococcal peptides specific to ARF/RHD. The availability of an appropriate animal model for this uniquely human disease can further facilitate the determination as to whether these peptides are pathognomonic. Identification of such peptides will also facilitate testing of potential anti-streptococcal vaccines for safety and avoid potential candidates that may pre-dispose potential vaccine recipients to adverse outcomes. Such peptides can also be readily incorporated into a universally affordable point of care device for both primary and tertiary care.

A global perspective of Indigenous child health research: a systematic review of longitudinal studies

BACKGROUND

Rigorously designed longitudinal studies can inform how best to reduce the widening health gap between Indigenous and non-Indigenous children.

METHODS

A systematic review was performed to identify and present the breadth and depth of longitudinal studies reporting the health and well-being of Indigenous children (aged 0-18 years) globally. Databases were searched up to 23 June 2020. Study characteristics were mapped according to domains of the life course model of health. Risk of bias was assessed using the National Institutes of Health (NIH) Study Quality Assessment Tools. Reported level of Indigenous involvement was also appraised; PROSPERO registration CRD42018089950.

RESULTS

From 5545 citations, 380 eligible papers were included for analysis, representing 210 individual studies. Of these, 41% were located in Australia (n = 88), 22.8% in the USA (n = 42), 11.9% in Canada (n = 25) and 10.9% in New Zealand (n = 23). Research tended to focus on either health outcomes (50.9%) or health-risk exposures (43.8%); 55% of studies were graded as 'good' quality; and 89% of studies made at least one reference to the involvement of Indigenous peoples over the course of their research.

CONCLUSIONS

We identified gaps in the longitudinal assessment of cultural factors influencing Indigenous child health at the macrosocial level, including connection to culture and country, intergenerational trauma, and racism or discrimination. Future longitudinal research needs to be conducted with strong Indigenous leadership and participation including holistic concepts of health. This is critical if we are to better understand the systematic factors driving health inequities experienced by Indigenous children globally.

Rheumatic heart disease in Indigenous young peoples

Indigenous children and young peoples live with an inequitable burden of acute rheumatic fever and rheumatic heart disease. In this Review, we focus on the epidemiological burden and lived experience of these conditions for Indigenous young peoples in Australia, New Zealand, and Canada. We outline the direct and indirect drivers of rheumatic heart disease risk and their mitigation. Specifically, we identify the opportunities and limitations of predominantly biomedical approaches to the primary, secondary, and tertiary prevention of disease among Indigenous peoples. We explain why these biomedical approaches must be coupled with decolonising approaches to address the underlying cause of disease. Initiatives underway to reduce acute rheumatic fever and rheumatic heart disease in Australia, New Zealand, and Canada are reviewed to identify how an Indigenous rights-based approach could contribute to elimination of rheumatic heart disease and global disease control goals.

Echocardiographic Screening Detects Rheumatic Heart Disease and Missed Opportunities in the Treatment of Group A Streptococcal Infections in Australian Torres Strait Islander Children

Rheumatic heart disease (RHD) is almost entirely preventable, but the incidence in indigenous Australians remains one of the highest in the world. A community-based echocardiogram screening program of 862 Torres Strait Islander children identified 25 (2.9%) new cases of RHD. Among these 25 children, 5/7 (71%) prior acute rheumatic fever presentations had not been recognized. There was a history of microbiologically confirmed group A Streptococcus infection in 17/25 (68%) children with RHD compared with 9/25 (36%) controls (odds ratio [OR] [95% CI]: 3.78 [1.17-12.19], P = 0.03). This was more likely to be a skin swab (16/25 [64%] cases versus 6/25 [24%] controls) than a throat swab (1/25 [4%] cases versus 3/25 [12%] controls) (OR [95% CI]: 5.33 [1.51-18.90] [P = 0.01]), supporting a role for skin infection in RHD pathogenesis. Household crowding and unemployment were common in the cohort, emphasizing the need for prioritizing strategies that address the social determinants of health. This study explores the burden of rheumatic heart disease diagnosed during an echocardiogram screening program in the Torres Strait Islands in tropical Australia and highlights the importance of primordial and primary prevention.

Scabies and impetigo in Samoa: A school-based clinical and molecular epidemiological study

Background

Common infections of the skin such as impetigo and scabies represent a large burden of disease globally, being particularly prevalent in tropical and resource-limited settings. Efforts to address these infections through mass drug administrations have recently been shown as efficacious and safe. In Samoa, a Pacific Island nation, there is a marked lack of epidemiological data for these neglected tropical diseases, or appreciation of their drivers in this setting.

Methods

An observational, cross-sectional survey of children aged between 4 and 15 years attending primary schools in rural areas of Upolu Island, Samoa was carried out to assess the prevalence of impetigo and scabies in schoolchildren residing in rural Samoa, integrated with descriptive epidemiological and microbial genomic data. A phylogenetic assessment of local Staphylococcus aureus isolated from Samoan schoolchildren was performed to estimate putative community transmission.

Findings

In this survey, the prevalence of impetigo observed in Samoan schoolchildren was one of the highest described globally (57•1%, 95% CI [53•8-60•5%], 476/833). Associations between active impetigo and age and gender were noted, with younger children and males more commonly affected (aOR2•8 [1•8-4•7]and aOR1•8 [1•3-2•5], respectively). The prevalence of scabies was similar to that seen in other South Pacific island countries (14•4%, 95% CI [12•2-17•0%], 120/833). Transmission of S. aureus was predicted, primarily between those children attending the same school. Carriage of S. pyogenes was notably low, with pharyngeal carriage observed in less than 2% of schoolchildren, consistent with earlier studies from Samoa.

Interpretation

This study describes a considerable burden of disease attributed to impetigo and scabies in Samoa. These findings will be valuable in addressing the public health challenge posed by these conditions, providing baseline prevalence data and highlighting practical strategies to reduce transmission of relevant microbes and parasites in this setting.

Tala Tomua

O a'afiaga o le pa'u i fa'ama'i o le po'u (impetigo) ma le utu o le pa'u (scabies), ua tele naua le fanau ua maua ai i le pasefika, ma le lalolagi atoa. O fuafuaga vaai mamao ma polokalame e fofoina ai nei faafitauli, e aofia ai le inumaga o fualaau e tapeina ai nei fa'ama'i, ua aliali mai ai e mafai ona faatamaia nei fa'ama'i. E le o tele ni tusitusiga ma faamaumauga i totonu o Samoa, pe ta'atele nei fa'amai o le pa'u pe leai. Ona o le le faatauaina o nei fa'ama'i, e le o iloa fo'i ni mafuaga ma nisi tulaga e faateleina ai nei fa'ama'i o le pa'u i Samoa.

Faatinoina o le suesuega

O le suesuega faasaenisi i le fanau aoga i le va o le 4 ma le 15 tausaga o loo ao'oga i le tulaga lua i nisi o nu'u i tua i Upolu, na faatinoina ai suesuega lea, ia suesueina ai le aotelega ma fainumera o le fanau ua maua i fa'ama'I o le po'u (impetigo) ma le utu o le pa'u (scabies). O lenei foi suesuega, na fia iloa ai fo'i po'o a ituaiga siama eseese o loo maua i luga o pa'u ma tino o le fanau aoga, ina ia iloa ai foi auala ua pipisi ai nei siama mai le isi tamaitiiti i le isi, ona mafua ai lea o nei fa'ama'i o le pa'u.

Tanuuga o le suesuega

Ua faailoa mai i le suesuega, le ta'atele o le fa'ama'i o le po'u (impetigo) ua maua ai le fanau aoga (57%), i aoga na faia ai le suesuega. O se fainumera ua maualuga tele i le lalolagi atoa. E toatele atu nisi o le fanau laiti (younger) ma tama (male) e maua i le po'u nai lo isi tamaiti. O le fainumera o le utu o le pa'u (scabies) (14·4%) e tai tutusa lava ma isi motu o le Pasefika. O le feaveaina o le siama faapitoa (staph aureus) ua tupu lea i le fanau ua ao'oga i le aoga e tasi. E le toatele foi nisi o le fanau (2%) na maua i le siama faapitoa o le fa'ai (strep pyogenes) e ona mafua ai le fiva rumatika. O lenei fainumera ua tai tutusa ma suesuega faasaenisi na fai muamua i Samoa.

Aotelega

O le aotelega la o lenei suesuega faasaenisi, ua faailoaina mai ai le tele naua o le fa'ama'i o le pa'u, o po'u (impetigo) ma le utu o le pa'u (scabies) i Samoa nei. O nei foi suesuega o le a aoga tele ini polokalame ma ni fuafuaga mamao e fa'afoisia ai nei faafitauli i le soifua maloloina o le fanau i Samoa. O le a avea foi nei fainumera e faamaumauina mo le silafia e le atunuu ma le soifua maloloina, le ta'atele o nei fa'amai o le pa'u, mo le tapenaina o ni fofo talafeagai ise taimi o i luma, ina ia faaitiitina ai le pipisi o nei siami i fanau ao'oga i Samoa.

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.

Intolerable Burden of Impetigo in Endemic Settings: A Review of the Current State of Play and Future Directions for Alternative Treatments

Impetigo (school sores) is a common superficial bacterial skin infection affecting around 162 million children worldwide, with the highest burden in Australian Aboriginal children. While impetigo itself is treatable, if left untreated, it can lead to life-threatening conditions, such as chronic heart and kidney diseases. Topical antibiotics are often considered the treatment of choice for impetigo, but the clinical efficacy of these treatments is declining at an alarming rate due to the rapid emergence and spread of resistant bacteria. In remote settings in Australia, topical antibiotics are no longer used for impetigo due to the troubling rise of antimicrobial resistance, demanding the use of oral and injectable antibiotic therapies. However, widespread use of these agents not only contributes to existing resistance, but also associated with adverse consequences for individuals and communities. These underscore the urgent need to reinvigorate the antibiotic discovery and alternative impetigo therapies in these settings. This review discusses the current impetigo treatment challenges in endemic settings in Australia and explores potential alternative antimicrobial therapies. The goals are to promote intensified research programs to facilitate effective use of currently available treatments, as well as developing new alternatives for impetigo.

Rheumatic heart disease: A review of the current status of global research activity

Rheumatic heart disease (RHD) is a serious and long-term consequence of acute rheumatic fever (ARF), an autoimmune sequela of a mucosal infection by Streptococcus pyogenes (Group A Streptococcus, Strep A). The pathogenesis of ARF and RHD is complex and not fully understood but involves host and bacterial factors, molecular mimicry, and aberrant host innate and adaptive immune responses that result in loss of self-tolerance and subsequent cross-reactivity with host tissues. RHD is entirely preventable yet claims an estimated 320 000 lives annually. The major burden of disease is carried by developing nations and Indigenous populations within developed nations, including Australia. This review will focus on the epidemiology, pathogenesis and treatment of ARF and RHD in Australia, where: streptococcal pyoderma, rather than streptococcal pharyngitis, and Group C and Group G Streptococcus, have been implicated as antecedents to ARF; the rates of RHD in remote Indigenous communities are persistently among the highest in the world; government register-based programs coordinate disease screening and delivery of prophylaxis with variable success; and researchers are making significant progress in the development of a broad-spectrum vaccine against Strep A.

The incidence of sore throat and group A streptococcal pharyngitis in children at high risk of developing acute rheumatic fever: A systematic review and meta-analysis

BACKGROUND

Group A streptococcal (GAS) pharyngitis has traditionally been considered the sole precursor of acute rheumatic fever (ARF). Evidence from Australia, however, suggests that GAS skin infections may contribute to the pathogenesis of ARF. A missing piece of evidence is the incidence of sore throat and GAS pharyngitis in this setting. We conducted a systematic review and meta-analysis of the incidence of sore throat and GAS pharyngitis in all children at risk of developing ARF.

METHODS

Databases were systematically searched for studies reporting on the incidence of pharyngitis among children from low to upper-middle income countries, and Indigenous children living in high-income countries. Studies were subjected to data extraction by two independent reviewers. Following an assessment of the methodological quality of the studies, we extracted incidence rates (IRs) and conducted a meta-analysis. This systematic review is registered on PROSPERO (CRD42019113019).

RESULTS

From 607 titles identified by the search, 11 articles met the predetermined inclusion criteria; ten studies reported IRs while for the remaining study, the incidence was calculated. The pooled incidence estimated for sore throat was 82.5 per 100 child-years (95% confidence interval [CI], 6.5 to 1044.4 per 100 child-years, I2 = 100%) and GAS pharyngitis was 10.8 per 100 child-years (95% CI, 2.3 to 50.0 per 100 child-years, I2 = 99.9%).

CONCLUSIONS

The pooled IRs for sore throat in children at risk of developing ARF were higher than rates reported in developed nations (32.70-40 per 100 child-years) and similar for GAS pharyngitis (12.8-14 per 100 years). The limited Australian data lend support to the need for further studies to inform the role of GAS pharyngitis in the development of ARF in Australian Indigenous children, so as to inform local primary prevention strategies for ARF and Rheumatic Heart Disease (RHD).

Streptococcal Infection as a Major Historical Cause of Stuttering: Data, Mechanisms, and Current Importance

Stuttering is one of the most well-known speech disorders, but the underlying neurological mechanisms are debated. In addition to genetic factors, there are also major non-genetic contributions. It is here proposed that infection with group A beta-hemolytic streptococcus (GAS) was a major underlying cause of stuttering until the mid-1900s when penicillin was introduced in 1943. The main mechanism proposed is an autoimmune reaction from tonsillitis, targeting specific molecules, for example within the basal ganglia. It is here also proposed that GAS infections may have continued to cause stuttering to some extent, to the present date, though more rarely. If so, early diagnosis of such cases would be of importance. Childhood cases with sudden onset of stuttering after throat infection may be particularly important to assess for possible GAS infection. The support for this hypothesis primarily comes from three lines of argument. First, medical record data from the 1930s strongly indicates that there was one type of medical event in particular that preceded the onset of childhood stuttering with unexpected frequency: diseases related to GAS throat infections. In particular, this included tonsillitis and scarlet fever, but also rheumatic fever. Rheumatic fever is a childhood autoimmune sequela of GAS infection, which was a relatively widespread medical problem until the early 1960s. Second, available reports of changes of the childhood prevalence of stuttering indicate striking parallels between stuttering and the incidence of rheumatic fever, with: (1) decline from the early 1900s; (2) marked decline from the introduction of penicillin in the mid 1940s; and (3) reaching a more stable level in the 1960s. The correlations between the data for stuttering and rheumatic fever after the introduction of penicillin are very high, at about 0.95. Third, there are established biological mechanisms linking GAS tonsillitis to immunological effects on the brain. Also, a small number of more recent case reports have provided further support for the hypothesis linking stuttering to GAS infection. Overall, it is proposed that the available data provides strong evidence for the hypothesis that GAS infection was a major cause of stuttering until the mid-1900s, interacting with genetic predisposition.

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.

Epidemiological consequences of enduring strain-specific immunity requiring repeated episodes of infection

Group A Streptococcus (GAS) skin infections are caused by a diverse array of strain types and are highly prevalent in disadvantaged populations. The role of strain-specific immunity in preventing GAS infections is poorly understood, representing a critical knowledge gap in vaccine development. A recent GAS murine challenge study showed evidence that sterilising strain-specific and enduring immunity required two skin infections by the same GAS strain within three weeks. This mechanism of developing enduring immunity may be a significant impediment to the accumulation of immunity in populations. We used an agent-based mathematical model of GAS transmission to investigate the epidemiological consequences of enduring strain-specific immunity developing only after two infections with the same strain within a specified interval. Accounting for uncertainty when correlating murine timeframes to humans, we varied this maximum inter-infection interval from 3 to 420 weeks to assess its impact on prevalence and strain diversity, and considered additional scenarios where no maximum inter-infection interval was specified. Model outputs were compared with longitudinal GAS surveillance observations from northern Australia, a region with endemic infection. We also assessed the likely impact of a targeted strain-specific multivalent vaccine in this context. Our model produced patterns of transmission consistent with observations when the maximum inter-infection interval for developing enduring immunity was 19 weeks. Our vaccine analysis suggests that the leading multivalent GAS vaccine may have limited impact on the prevalence of GAS in populations in northern Australia if strain-specific immunity requires repeated episodes of infection. Our results suggest that observed GAS epidemiology from disease endemic settings is consistent with enduring strain-specific immunity being dependent on repeated infections with the same strain, and provide additional motivation for relevant human studies to confirm the human immune response to GAS skin infection.

Group A Streptococcus (GAS) is a ubiquitous bacterial pathogen that exists in many distinct strains, and is a major cause of death and disability globally. Vaccines against GAS are under development, but their effective use will require better understanding of how immunity develops following infection. Evidence from an animal model of skin infection suggests that the generation of enduring strain-specific immunity requires two infections by the same strain within a short time frame. It is not clear if this mechanism of immune development operates in humans, nor how it would contribute to the persistence of GAS in populations and affect vaccine impact. We used a mathematical model of GAS transmission, calibrated to data collected in an Indigenous Australian community, to assess whether this mechanism of immune development is consistent with epidemiological observations, and to explore its implications for the impact of a vaccine. We found that it is plausible that repeat infections are required for the development of immunity in humans, and illustrate the difficulties associated with achieving sustained reductions in disease prevalence with a vaccine.

Group A Streptococcus

Group A Streptococcus (GAS) or Streptococcus pyogenes, affects an estimated 800 million people each year. Most of the resulting estimated 639,000 annual deaths are related to rheumatic heart disease (RHD) and its complications. Resource-limited areas account for the vast majority of cases, although outbreaks still occur in industrialized countries. GAS has several mechanisms to avoid phagocytosis, including prevention of opsonization and the use of surface proteins to block complement fixation. The mechanisms behind the immunologic phenomenon are not well understood. Clinical presentations range from benign, short-lived impetigo or pharyngitis through to lifelong RHD. In its most invasive form, GAS can cause a rapidly progressive, often lethal infection: streptococcal toxic shock syndrome. S. pyogenes remains universally sensitive to penicillin, which is the mainstay of treatment.

Risk Factors for Acute Rheumatic Fever: Literature Review and Protocol for a Case-Control Study in New Zealand

Acute rheumatic fever (ARF) and its sequela, rheumatic heart disease (RHD), have largely disappeared from high-income countries. However, in New Zealand (NZ), rates remain unacceptably high in indigenous Māori and Pacific populations. The goal of this study is to identify potentially modifiable risk factors for ARF to support effective disease prevention policies and programmes. A case-control design is used. Cases are those meeting the standard NZ case-definition for ARF, recruited within four weeks of hospitalisation for a first episode of ARF, aged less than 20 years, and residing in the North Island of NZ. This study aims to recruit at least 120 cases and 360 controls matched by age, ethnicity, gender, deprivation, district, and time period. For data collection, a comprehensive pre-tested questionnaire focussed on exposures during the four weeks prior to illness or interview will be used. Linked data include previous hospitalisations, dental records, and school characteristics. Specimen collection includes a throat swab (Group A Streptococcus), a nasal swab (Staphylococcus aureus), blood (vitamin D, ferritin, DNA for genetic testing, immune-profiling), and head hair (nicotine). A major strength of this study is its comprehensive focus covering organism, host and environmental factors. Having closely matched controls enables the examination of a wide range of specific environmental risk factors.

Skin infections in Australian Aboriginal children: a narrative review

Impetigo, scabies, cellulitis and abscesses are common in Australian Aboriginal children. These conditions adversely affect wellbeing and are associated with serious long term sequelae, including invasive infection and post‐infectious complications, such as acute post‐streptococcal glomerulonephritis and acute rheumatic fever, which occurs at the highest documented rates in the world in remote Aboriginal communities.

Observational research in remote communities in northern Australia has demonstrated a high concurrent burden of scabies and impetigo and their post‐infectious complications.

Few data are available for other Australian states, especially for urban Aboriginal children; however, nationwide hospital data indicate that the disparity between Aboriginal and non‐Aboriginal children in skin infection prevalence also exists in urban settings.

The Australian National Healthy Skin Guideline summarises evidence‐based treatment of impetigo, scabies and fungal infections in high burden settings such as remote Aboriginal communities. It recommends systemic antibiotics for children with impetigo, and either topical permethrin or oral ivermectin (second line) for the individual and their contacts as equally efficacious treatments for scabies. β‐Lactams are the treatment of choice and trimethoprim–sulfamethoxazole and clindamycin are effective alternatives for treatment of paediatric cellulitis. Abscesses require incision and drainage and a 5‐day course of trimethoprim–sulfamethoxazole or clindamycin.

Addressing normalisation of skin infections and the social determinants of skin health are key challenges for the clinician. Research is underway on community‐wide skin health programs and the role for mass drug administration which will guide future management of these common, treatable diseases.

Group G Streptococcus Induces an Autoimmune Carditis Mediated by Interleukin 17A and Interferon γ in the Lewis Rat Model of Rheumatic Heart Disease

Acute rheumatic fever and rheumatic heart disease (ARF/RHD) have long been described as autoimmune sequelae of Streptococcus pyogenes or group A streptococcal (GAS) infection. Both antibody and T-cell responses against immunodominant GAS virulence factors, including M protein, cross-react with host tissue proteins, triggering an inflammatory response leading to permanent heart damage. However, in some ARF/RHD-endemic regions, throat carriage of GAS is low. Because Streptococcus dysgalactiae subspecies equisimilis organisms, also known as β-hemolytic group C streptococci and group G streptococci (GGS), also express M protein, we postulated that streptococci other than GAS may have the potential to initiate or exacerbate ARF/RHD. Using a model initially developed to investigate the uniquely human disease of ARF/RHD, we have discovered that GGS causes interleukin 17A/interferon γ-induced myocarditis and valvulitis, hallmarks of ARF/RHD. Remarkably the histological, immunological, and functional changes in the hearts of rats exposed to GGS are identical to those exposed to GAS. Furthermore, antibody cross-reactivity to cardiac myosin was comparable in both GGS- and GAS-exposed animals, providing additional evidence that GGS can induce and/or exacerbate ARF/RHD.

Asymptomatic pharyngeal carriage rate of Streptococcus pyogenes, its associated factors and antibiotic susceptibility pattern among school children in Hawassa town, southern Ethiopia

Objectives

The aim of this study was to determine the asymptomatic pharyngeal carriage rate of S. pyogenes, antimicrobial pattern and related risk factors among school children in Hawassa, southern Ethiopia.

Results

Out of 287 school children’s screened, 35 (12.2%) were colonized with S. pyogenes. The carriage rate was significantly associated with factors such as sex (female p = 0.013) occupational status of mother (p = 0.002), lower income source (500–900 ETB, 1000–1500 ETB) (p = 0.001, and p = 0.042), history of hospitalization (p = 0.00) and residence of the children (p = 0.002). High level resistant to tetracycline and low level to vancomycin were observed, while penicillin, amoxicillin, erythromycin, chloramphenicol, and ceftriaxone were found to be effective.

Concerns for efficacy of a 30-valent M-protein-based Streptococcus pyogenes vaccine in regions with high rates of rheumatic heart disease

The prevalence of rheumatic heart disease (RHD) in the Aboriginal population of the Australian Northern Territory is high, and Streptococcus pyogenes skin infections likely contribute to this. A promising candidate S. pyogenes “30mer” vaccine is composed of 30 pharyngitis associated type-specific antigens from the S. pyogenes M protein. Cross opsonisation experiments suggest that 30mer vaccine protection may extend to non-cognate emm types. A new “emm cluster” scheme for classifying M protein is based on the full-length coding sequence, and correlates with functional and immunological properties, and anatomical tropism. Twenty-seven years of research in the Northern Territory has yielded 1810 S. pyogenes isolates with clinical and emm type data. The primary aim was to analyse these data with reference to the emm cluster scheme and cross opsonisation information, to inform estimation of 30mer vaccine efficacy in the Northern Territory. The isolates encompass 101 emm types. Variants of cluster A-C were enriched in throat isolates, and variants of emm cluster D enriched in skin isolates. Throat isolates were enriched for 30mer vaccine cognate emm types in comparison with skin isolates of which only 25% were vaccine emm types. While cross opsonisation data indicates potential for enhancing 30mer vaccine coverage, more than one third of skin isolates were within 38 emm types untested for cross opsonisation. Emm cluster D variants, in particular emm cluster D4, were not only all non-cognate with the vaccine, but were abundant and diverse, and less likely to be cross-opsonisation positive than other emm clusters. Long term persistence of many emm types in the study area was revealed. It was concluded that the 30mer vaccine efficacy in the Northern Territory will likely require both cross protection, and additional measures to elicit immunity against variants of emm cluster D.

The bacterium Streptococcus pyogenes causes throat and skin infections. A danger from such infections is an immune response that attacks human heart tissue, leading to rheumatic heart disease, which is difficult to treat and potentially deadly. Disadvantaged populations such as the Indigenous people in remote tropical northern Australia have high burdens of S. pyogenes skin infection, and rheumatic heart disease. An effective vaccine would be a benefit, but none is approved for clinical use. We analysed data from 1810 S. pyogenes isolates from north Australia obtained over 28 years, to determine the potential of a previously described S. pyogenes vaccine candidate to be effective in this region. Only one quarter of the isolates from skin infections had a surface antigen corresponding to any one of the 30 antigen variants in the candidate vaccine. Previous work in animals indicates potential cross-protection from the vaccine against strains with mismatched antigens. However, even if this occurs in humans, protection against skin infection strains would likely remain compromised, unless there were additional components in the vaccine. Further studies on cross-protection are critical to defining the potential of this type of vaccine in populations burdened with S. pyogenes skin infections and rheumatic heart disease.

A cluster of acute rheumatic fever cases among Aboriginal Australians in a remote community with high baseline incidence

OBJECTIVES

We report a cluster of acute rheumatic fever (ARF) cases and the public health response in a high-burden Australian setting.

METHODS

The public health unit was notified of an increase in ARF cases in a remote Australian Aboriginal community. A multi-disciplinary group coordinated the response. Household contacts were screened for ARF or group A Streptococcus (GAS) infection by questionnaire and swab collection, offered an echocardiogram if aged 5-20 years, and intramuscular benzathine benzylpenicillin if aged over one year or if less than one year with impetigo.

RESULTS

Fifteen definite and seven probable ARF cases were diagnosed in the community in July-December 2014 (all-age incidence of definite ARF: 1,473/100,000). The public health response identified two additional cases of ARF. A total of 81 contacts were screened; GAS was detected in 3/76 (4%) throat swabs and 11/24 (46%) skin swabs. Molecular typing revealed high GAS strain diversity.

CONCLUSIONS

The incidence of ARF during this cluster was very high. Carriage and infection with GAS was observed, but no outbreak strain identified. Implications for public health: A national public health guideline has since been developed that includes advice on the investigation of an ARF outbreak/cluster. Sustained efforts with strong community engagement are required to tackle high ARF rates.

Potential for Molecular Testing for Group A Streptococcus to Improve Diagnosis and Management in a High-Risk Population: A Prospective Study

Background

In high-burden settings, guidelines recommend antibiotic treatment for all suspected group A Streptococcus (GAS) infections to prevent rheumatic fever and poststreptococcal glomerulonephritis. Highly sensitive rapid GAS tests could reduce unnecessary antibiotic use in these settings.

Methods

This was a prospective study of the Xpert Xpress Strep A (Cepheid) molecular test compared with culture of throat swab samples collected at a referral hospital in northern Australia. Demographic and clinical data and results of streptococcal serology and culture were collected.

Results

Of 164 throat swab samples, 145 (88%) were eligible for inclusion; 49 (34%) were molecular test positive and 24 (17%) were culture positive for GAS. The sensitivity, specificity, and positive and negative predictive values for the molecular test versus culture were 100.0%, 79.3%, 48.8%, and 100.0%, respectively. Among 25 samples testing positive with the molecular test and negative with culture, group C or G streptococci were cultured in 2, and a plausible clinical explanation, such as pharyngotonsillitis, or rheumatic fever with positive results of streptococcal serology, was apparent in 19 instances. In 25 patients with rheumatic fever or poststreptococcal glomerulonephritis diagnoses, molecular testing nearly trebled the detection of GAS in throat swab samples, from 3 (12%) detected with culture to 8 (32%) detected with molecular testing. Reasons for “false-positive” molecular test results could include the presence of GAS below the threshold of culture detection or persistence of nonviable organisms after infection.

Conclusion

Implementation of molecular testing could improve antibiotic use in this high-burden setting. The incremental yield in poststreptococcal syndromes, by which time cultures are negative, has high potential in the diagnostic workup of autoimmune poststreptococcal syndromes and warrants further investigation.

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.

Streptococcal Serology in Acute Rheumatic Fever Patients: Findings From 2 High-income, High-burden Settings

BACKGROUND

Globally, there is wide variation in streptococcal titer upper limits of normal (ULN) for antistreptolysin O (ASO) and anti-deoxyribonuclease B (ADB) used as an evidence of recent group A streptococcal infection to diagnose acute rheumatic fever (ARF).

METHODS

We audited ASO and ADB titers among individuals with ARF in New Zealand (NZ) and in Australia's Northern Territory. We summarized streptococcal titers by different ARF clinical manifestations, assessed application of locally recommended serology guidelines where NZ uses high ULN cut-offs and calculated the proportion of cases fulfilling alternative serologic diagnostic criteria.

RESULTS

From January 2013 to December 2015, group A streptococcal serology results were available for 350 patients diagnosed with ARF in NZ and 182 patients in Northern Territory. Median peak streptococcal titers were similar in both settings. Among NZ cases, 267/350 (76.3%) met NZ serologic diagnostic criteria, whereas 329/350 (94.0%) met Australian criteria. By applying Australian ULN titer cut-off criteria to NZ cases, excluding chorea, ARF definite cases would increase by 17.6% representing 47 cases.

CONCLUSIONS

ASO and ADB values were similar in these settings. Use of high ULN cut-offs potentially undercounts definite and probable ARF diagnoses. We recommend NZ and other high-burden settings to use globally accepted, age-specific, lower serologic cut-offs to avoid misclassification of ARF.

Group A streptococcal M-like proteins: From pathogenesis to vaccine potential

M and M-like surface proteins from group A Streptococcus (GAS) act as virulence factors and have been used in multiple vaccine candidates. While the M protein has been extensively studied, the two genetically and functionally related M-like proteins, Mrp and Enn, although present in most streptococcal strains have been relatively less characterised. We compile the current state of knowledge for these two proteins, from discovery to recent studies on function and immunogenicity, using the M protein for comparison as a prototype of this family of proteins. We focus on the known interactions between M-like proteins and host ligand proteins, and analyse the genetic data supporting these interactions. We discuss known and possible functions of M-like proteins during GAS infections, and highlight knowledge gaps where further investigation is warranted.

Clinical Screening Tools to Diagnose Group A Streptococcal Pharyngotonsillitis in Primary Care Clinics to Improve Prescribing Habits

This review highlights the clinical scoring tools used for the management of acute pharyngotonsillitis in primary care clinics. It will include the prevalence of group A pharyngotonsillitis among children and adults worldwide and the selective tests employed for diagnosing group A streptococcal pharyngotonsillitis. Pharyngotonsillitis is one of the common reasons for visits to primary care clinics worldwide, and physicians tend to prescribe antibiotics according to the clinical symptoms, which leads to overprescribing antibiotics. This in turn may lead to serious health impacts and severe reactions and may promote antibiotic resistance. These significantly add on to the health care costs. The available information from health organisations and previous studies has indicated the need to manage the diagnosis of pharyngotonsillitis to improve prescribing habits in primary care clinics.

An economic case for a vaccine to prevent group A streptococcus skin infections

BACKGROUND

Group A streptococcus (GAS) causes an exceptionally diverse range of diseases, raising questions about the optimal product characteristics of a commercially viable vaccine. The objectives of this study were to (1) estimate the current health and economic burdens caused by 24 diseases attributable to GAS each year in Australia and (2) use these estimates to explore the value of a GAS vaccine for different clinical indications, age schedules, and population groups.

METHODS

For objective 1, we estimated the population heath and economic burdens by synthesising data from administrative databases, nationally representative surveys, literature reviews, public reimbursement schedules, and expert opinion. For objective 2, we modelled the prospective lifetime burden of GAS for all infants from birth, for children from 5 years of age, and for adults from 65 years of age. A vaccine was assumed to reduce each GAS disease by 70% for a period of 10 years, and the difference in outcomes between vaccinated and non-vaccinated cohorts were used to calculate the cost-effective value of vaccination.

RESULTS

The annual health and economic burdens of GAS diseases totalled 23,528 disability-adjusted life years and AU$185.1 million in healthcare costs respectively; approximately half of each measure was due to cellulitis, followed by other skin infections and throat infections. Reducing the incidence of throat infections, skin infections, and cellulitis in non-Indigenous cohorts resulted in 30%, 33%, and 28% of the total vaccine value for an infant schedule (cost-effective vaccine price AU$260 per course); 47%, 26%, and 22% of the value for a child schedule (AU$289); and 2%, 15% and 74% for an adult schedule (AU$489).

CONCLUSIONS

A vaccine that prevents GAS cellulitis and other skin infections, in addition to throat infections, would maximise its value and commercial viability, with a cost-effective price in line with other recently-licensed and funded vaccines in Australia.

"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.