Tropical acute rheumatic fever and associated streptococcal infections compared with concurrent acute glomerulonephritis

How strong is the relationship between scabies and acute rheumatic fever? An analysis of neighbourhood factors

AIM

Recent studies have linked scabies with acute rheumatic fever (ARF). We explored the relationship, by neighbourhood, between permethrin dispensing as an indicator of scabies prevalence and ARF cases over the same period.

METHODS

Incident cases of ARF notified to public health between September 2015 and June 2018 and the annual incidence of prescribing by neighbourhood over the same period were analysed. Evidence of an association between permethrin and ARF was obtained by carrying out Poisson regression of the rate of ARF in terms of permethrin rate at the census area unit level, with adjustment for ethnicity and socio-economic deprivation.

RESULTS

A total of 413 neighbourhoods were included. The incidence of ARF varied between 0 and 102 per 100 000 people per year (mean 4.3). In contrast, the annual incidence of dispensing of permethrin varied between 0 and 3201 per 100 000 people per year (mean 771). A strong association was observed between the two variables. In an adjusted quasi-Poisson model, permethrin-dispensing rates were strongly associated with ARF incidence, with a change from the 16th to the 84th centile associated with a 16.5-fold increase in incidence (95% confidence interval: 3.82-71.6).

CONCLUSIONS

Permethrin prescribing as an indicator of scabies is strongly associated with the incidence of ARF. Considered together with other studies, this evidence suggests that improving scabies control may reduce the burden of ARF in New Zealand.

Molecular Epidemiology, Ecology, and Evolution of Group A Streptococci

The clinico-epidemiological features of diseases caused by group A streptococci (GAS) is presented through the lens of the ecology, population genetics, and evolution of the organism. The serological targets of three typing schemes (M, T, SOF) are themselves GAS cell surface proteins that have a myriad of virulence functions and a diverse array of structural forms. Horizontal gene transfer expands the GAS antigenic cell surface repertoire by generating numerous combinations of M, T, and SOF antigens. However, horizontal gene transfer of the serotype determinant genes is not unconstrained, and therein lies a genetic organization that may signify adaptations to a narrow ecological niche, such as the primary tissue reservoirs of the human host. Adaptations may be further shaped by selection pressures such as herd immunity. Understanding the molecular evolution of GAS on multiple levels-short, intermediate, and long term-sheds insight on mechanisms of host-pathogen interactions, the emergence and spread of new clones, rational vaccine design, and public health interventions.

Differences in SpeB protease activity among group A streptococci associated with superficial, invasive, and autoimmune disease

The secreted cysteine proteinase SpeB is an important virulence factor of group A streptococci (GAS), whereby SpeB activity varies widely among strains. To establish the degree to which SpeB activity correlates with disease, GAS organisms were recovered from patients with pharyngitis, impetigo, invasive disease or acute rheumatic fever (ARF), and selected for analysis using rigorous sampling criteria; >300 GAS isolates were tested for SpeB activity by casein digestion assays, and each GAS isolate was scored as a SpeB-producer or non-producer. Highly significant statistical differences (p < 0.01) in SpeB production are observed between GAS recovered from patients with ARF (41.5% SpeB-non-producers) compared to pharyngitis (20.5%), invasive disease (16.7%), and impetigo (5.5%). SpeB activity differences between pharyngitis and impetigo isolates are also significant, whereas pharyngitis versus invasive isolates show no significant difference. The disproportionately greater number of SpeB-non-producers among ARF-associated isolates may indicate an altered transcriptional program for many rheumatogenic strains and/or a protective role for SpeB in GAS-triggered autoimmunity.

[Consensus document on the diagnosis and treatment of acute tonsillopharyngitis]

Acute tonsillopharyngitis is one of the most common childhood diseases. Viruses are the most frequent origin. Group A Streptococcus (Streptococcus pyogenes) is the main bacterial cause. A culture or a rapid antigen-detection test of a throat-swab specimen should only be done on the basis of clinical scores, in order to avoid over-diagnosis of bacterial origin and unnecessary antibiotic prescription. The objectives of treatment are: the reduction of symptoms, reduce the contagious period, and prevent local suppurative and systemic complications. Ideally, only confirmed cases should receive antibiotics. If there is no possibility to perform a rapid antigen-detection test, or in some cases if the result is negative, it is recommended to perform a culture and, if there is high suspicious index, to prescribe antibiotics. Penicillin is the treatment of choice, although amoxicillin is also accepted as the first option. Amoxicillin/clavulanate is not indicated in any case as empirical treatment. Macrolides are not a first choice antibiotic, and should be reserved for those patients with immediate penicillin allergy reaction or for the treatment of streptococcal carriers. It is of primordial importance to adapt the prescribing of antibiotics to the scientific evidence.

Whole-genome association study on tissue tropism phenotypes in group A Streptococcus

Group A Streptococcus (GAS) has a rich evolutionary history of horizontal transfer among its core genes. Yet, despite extensive genetic mixing, GAS strains have discrete ecological phenotypes. To further our understanding of the molecular basis for ecological phenotypes, comparative genomic hybridization of a set of 97 diverse strains to a GAS pangenome microarray was undertaken, and the association of accessory genes with emm genotypes that define tissue tropisms for infection was determined. Of the 22 nonprophage accessory gene regions (AGRs) identified, only 3 account for all statistically significant linkage disequilibrium among strains having the genotypic biomarkers for throat versus skin infection specialists. Networked evolution and population structure analyses of loci representing each of the AGRs reveal that most strains with the skin specialist and generalist biomarkers form discrete clusters, whereas strains with the throat specialist biomarker are highly diverse. To identify coinherited and coselected accessory genes, the strength of genetic associations was determined for all possible pairwise combinations of accessory genes among the 97 GAS strains. Accessory genes showing very strong associations provide the basis for an evolutionary model, which reveals that a major transition between many throat and skin specialist haplotypes correlates with the gain or loss of genes encoding fibronectin-binding proteins. This study employs a novel synthesis of tools to help delineate the major genetic changes associated with key adaptive shifts in an extensively recombined bacterial species.

Typing of the pilus-protein-encoding FCT region and biofilm formationas novel parameters in epidemiological investigations of Streptococcuspyogenes isolates from various infection sites

Streptococcus pyogenes is an important human pathogen for whichan association between infection site and selected epidemiological or functionalmarkers has previously been suggested. However, the studies involved oftenused strains with an insufficiently defined clinical background and laboratoryhistory. Thus, the major goal of the present study was to investigate theserelationships in 183 prospectively collected, well-defined, low-passage isolatesfrom a North-East German centre for tertiary care. For each isolate the clinicalbackground (91 respiratory, 71 skin and 21 invasive isolates) andantibiotic-resistance pattern was recorded. All isolates were classified accordingto their emm type, antibiotic-resistance and PFGE pattern (SmaI restriction analysis of genomic DNA). As novel discriminatorymethods we performed a PCR-based typing of the pilus-protein-encoding FCTregion (FCT) and biofilm-formation phenotyping in various culturemedia. Forty-one isolates were found to be resistant to at least one of thetested antibiotics. emm typing revealed emm28, emm12, emm1, emm4, emm89 and emm2 as themost frequent types in our collection. The novel FCT typing showed isolatesencoding FCT types 4 and 2 to be the most common. Overall 113 strains withunique combinations of emm and FCT types, antibiotic-resistance andPFGE patterns were identified. The majority of all isolates revealed an associationof biofilm-formation capacity with growth media. Comparing all results forpotential associations, no correlation could be established between the anatomicalsite of isolation and the emm or the FCT type. There was no relationshipbetween biofilm formation and emm type, antibiotic-resistance orPFGE patterns. However, a novel association between biofilm formation andFCT type became obvious among strains from our collection.

Group A Streptococcal Isolates Temporally Associated with Acute Rheumatic Fever in Hawaii: Differences from the Continental United States

BACKGROUND

The annual incidence of acute rheumatic fever (ARF) in Hawaii has remained several times higher than that in the continental United States, particularly among ethnic Polynesians. The emm types of Streptococcus pyogenes that are associated with this nonsuppurative complication have, to our knowledge, not been previously reported in Hawaii.

METHODS

Patients with ARF were identified through an active surveillance system at Kapiolani Medical Center (Honolulu, HI), the only pediatric tertiary care referral hospital in Hawaii. Specimens were obtained by throat culture from patients who met the Jones criteria for ARF at the time of presentation (63 patients), prior to penicillin treatment, and from consenting family contacts (10 individuals). Eight patients and 2 close family contacts with positive throat culture results were identified from February 2000 through December 2005. Group A streptococci isolates were characterized by emm sequence typing.

RESULTS

Unusual emm types were temporally associated with the onset of ARF. Emm types 65/69 (from 2 patients), 71, 92, 93, 98, 103, and 122 were isolated from the 8 patients with ARF, and emm types 52 and 101 were isolated from the 2 household contacts.

CONCLUSIONS

So-called rheumatogenic emm types and/or serotypes, which were previously associated with ARF in the continental United States, were not found in this study. Instead, emm types that are not commonly included among group A streptococci isolates in the continental United States and that are seldom, if ever, temporally associated with ARF were identified. These findings suggest that unusual group A streptococci emm types play a significant role in the epidemiology of ARF in Hawaii.

The dynamic nature of group A streptococcal epidemiology in tropical communities with high rates of rheumatic heart disease

Prospective surveillance was conducted in three remote Aboriginal communities with high rates of rheumatic heart disease in order to investigate the epidemiology of group A beta-haemolytic streptococci (GAS). At each household visit, participants were asked about sore throat. Swabs were taken from all throats and any skin sores. GAS isolates were emm sequence and pattern-typed using standard laboratory methods. There were 531 household visits; 43 different emm types and subtypes (emmST) were recovered. Four epidemiological patterns were observed. Multiple emmST were present in the population at any one time and household acquisition rates were high. Household acquisition was most commonly via 5- to 9-year-olds. Following acquisition, there was a 1 in 5 chance of secondary detection in the household. Throat detection of emmST was brief, usually <2 months. The epidemiology of GAS in these remote Aboriginal communities is a highly dynamic process characterized by emmST diversity and turnover.

Identification of a streptococcal octapeptide motif involved in acute rheumatic fever

Acute rheumatic fever is a serious autoimmune sequela of pharyngitis caused by certain group A streptococci. One mechanism applied by streptococcal strains capable of causing acute rheumatic fever is formation of an autoantigenic complex with human collagen IV. In some geographic regions with a high incidence of acute rheumatic fever pharyngeal carriage of group C and group G streptococci prevails. Examination of such strains revealed the presence of M-like surface proteins that bind human collagen. Using a peptide array and recombinant proteins with targeted amino acid substitutions, we could demonstrate that formation of collagen complexes during streptococcal infections depends on an octapeptide motif, which is present in collagen binding M and M-like proteins of different beta-hemolytic streptococcal species. Mice immunized with streptococcal proteins that contain the collagen binding octapeptide motif developed high serum titers of anti-collagen antibodies. In sera of rheumatic fever patients such a collagen autoimmune response was accompanied by specific reactivity against the collagen-binding proteins, linking the observed effect to clinical cases. Taken together, the data demonstrate that the identified octapeptide motif through its action on collagen plays a crucial role in the pathogenesis of rheumatic fever. Eradication of streptococci that express proteins with the collagen binding motif appears advisable for controlling rheumatic fever.

Molecular typing of Streptococcus pyogenes from remote Aboriginal communities where rheumatic fever is common and pyoderma is the predominant streptococcal infection

Aboriginal Australians in remote communities have high rates of rheumatic heart disease (RHD); yet pharyngitis is reportedly rare whilst pyoderma is common. Some strains of group A streptococci (GAS) have preference for the throat and others for the skin depending on M protein type. A study in three remote communities provided 350 GAS isolates for emm sequence typing, 244 were also emm pattern typed. There was 100% correlation between emm sequence and pattern type. Patterns D and E (non-throat tropic) made up 71% of throat and 87% of skin isolates although patterns A-C (throat tropic) were more common in the throat than the skin (RR 2.3, 95% CI 1.4-3.8) whilst the opposite was found for pattern D (RR 2.2, 95% CI 1.7-3.0). Pattern E favoured the throat (RR 1.4, 95% CI 1.1-1.8). Where environmental factors predispose to skin infection, emm pattern types D and E prevail, whatever the recovery site.

Population genetics and linkage analysis of loci within the FCT region of Streptococcus pyogenes

The FCT regions of Streptococcus pyogenes strains encode a variety of cell wall-anchored surface proteins that bind the extracellular matrix of the human host and/or give rise to pilus-like appendages. Strong linkage is evident between transcription-regulatory loci positioned within the FCT and emm regions and the emm pattern genotype marker for preferred infection of the throat or skin. These findings provide a basis for the hypothesis that FCT region gene products contribute to tissue-specific infection. In an initial series of steps to address this possibility, the FCT regions of 13 strains underwent comparative sequence analysis, the gene content of the FCT region was characterized for 113 strains via PCR, and genetic linkage was assessed. A history of extensive recombination within FCT regions was evident. The emm pattern D-defined skin specialist strains were highly homogenous in their FCT region gene contents, whereas the emm pattern A-C-defined throat specialist strains displayed a greater variety of forms. Most pattern A-C strains harbored prtF1 (75%) but lacked cpa (75%). In contrast, the majority of emm pattern D strains had cpa (92%) but lacked prtF1 (79%). Models based on FCT and emm region genotypes revealed the most parsimonious pathways of evolution. Using niche-determining candidate genes to infer phylogeny, emm pattern E strains--the so-called generalists, which lack a strong tissue site preference--occupied a transition zone separating most throat specialists from skin specialists. Overall, population genetic analysis supports the possibility that the FCT region gives rise to surface proteins that are largely necessary, but not always sufficient, to confer tissue site preference for infection.

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

BACKGROUND

Acute rheumatic fever is a major cause of heart disease in Aboriginal Australians. The epidemiology differs from that observed in regions with temperate climates; streptococcal pharyngitis is reportedly rare, and pyoderma is highly prevalent. A link between pyoderma and acute rheumatic fever has been proposed but is yet to be proven. Group C beta-hemolytic streptococci and group G beta-hemolytic streptococci have also been also implicated in the pathogenesis.

METHODS

Monthly, prospective surveillance of selected households was conducted in 3 remote Aboriginal communities. People were questioned about sore throat and pyoderma; swab specimens were obtained from all throats and any pyoderma lesions. Household population density was determined.

RESULTS

From data collected during 531 household visits, the childhood incidence of sore throat was calculated to be 8 cases per 100 person-years, with no cases of symptomatic group A beta-hemolytic streptococci pharyngitis. The median point prevalence for throat carriage was 3.7% for group A beta-hemolytic streptococci, 0.7% for group C beta-hemolytic streptococci, and 5.1% for group G beta-hemolytic streptococci. Group A beta-hemolytic streptococci were recovered from the throats of 19.5% of children at some time during the study. There was no seasonal trend or correlation with overcrowding. Almost 40% of children had pyoderma at least once, and the prevalence was greatest during the dry season. In community 1, the prevalence of pyoderma correlated with household crowding. Group C and G beta-hemolytic streptococci were rarely recovered from pyoderma lesions.

CONCLUSIONS

These data are consistent with the hypothesis that recurrent skin infections immunize against throat colonization and infection. High rates of acute rheumatic fever were not driven by symptomatic group A beta-hemolytic streptococci throat infection. Group G and C beta-hemolytic streptococci were found in the throat but rarely in pyoderma lesions.

Acute rheumatic fever

Acute rheumatic fever (ARF) and its chronic sequela, rheumatic heart disease (RHD), have become rare in most affluent populations, but remain unchecked in developing countries and in some poor, mainly indigenous populations in wealthy countries. More than a century of research, mainly in North America and Europe, has improved our understanding of ARF and RHD. However, whether traditional views need to be updated in view of the epidemiological shift of the past 50 years is still to be established, and improved data from developing countries are needed. Doctors who work in populations with a high incidence of ARF are adapting existing diagnostic guidelines to increase their sensitivity. Group A streptococcal vaccines are still years away from being available and, even if the obstacles of serotype coverage and safety can be overcome, their cost could make them inaccessible to the populations that need them most. New approaches to primary prevention are needed given the limitations of primary prophylaxis as a population-based strategy. The most effective approach for control of ARF and RHD is secondary prophylaxis, which is best delivered as part of a coordinated control programme.

Evolution of transcription regulatory genes is linked to niche specialization in the bacterial pathogen Streptococcus pyogenes

Streptococcus pyogenes is a highly prevalent bacterial pathogen, most often giving rise to superficial infections at the throat or skin of its human host. Three genotype-defined subpopulations of strains exhibiting strong tropisms for either the throat or skin (specialists) or having no obvious tissue site preference (generalists) are recognized. Since the microenvironments at the throat and skin are distinct, the signal transduction pathways leading to the control of gene expression may also differ for throat versus skin strains of S. pyogenes. Two loci (mga and rofA/nra) encoding global regulators of virulence gene expression are positioned 300 kb apart on the genome; each contains alleles forming two major sequence clusters of approximately 25 to 30% divergence that are under balancing selection. Strong linkage disequilibrium is observed between sequence clusters of the transcription regulatory loci and the subpopulations of throat and skin specialists, against a background of high recombination rates among housekeeping genes. A taxonomically distinct commensal species (Streptococcus dysgalactiae subspecies equisimilus) shares highly homologous rof alleles. The findings provide strong support for a mechanism underlying niche specialization that involves orthologous replacement of regulatory genes following interspecies horizontal transfer, although the directionality of gene exchange remains unknown.

Acute rheumatic fever: a chink in the chain that links the heart to the throat?

Acute rheumatic fever (ARF) remains a major problem in tropical regions, resource-poor countries, and minority indigenous communities. It has long been thought that group A streptococcal (GAS) pharyngitis alone was responsible for acute rheumatic fever; this belief has been supported by laboratory and epidemiological evidence gathered over more than 60 years, mainly in temperate climates where GAS skin infection is uncommon. GAS strains have been characterised as either rheumatogenic or nephritogenic based on phenotypic and genotypic properties. Primary prevention strategies and vaccine development have long been based on these concepts. The epidemiology of ARF in Aboriginal communities of central and northern Australia challenges this view with reported rates of ARF and rheumatic heart disease (RHD) that are among the highest in the world. GAS throat colonisation is uncommon, however, and symptomatic GAS pharyngitis is rare; pyoderma is the major manifestation of GAS infection. Typical rheumatogenic strains do not occur. Moreover, group C and G streptococci have been shown to exchange key virulence determinants with GAS and are more commonly isolated from the throats of Aboriginal children. We suggest that GAS pyoderma and/or non-GAS infections are driving forces behind ARF in these communities and other high-incidence settings. The question needs to be resolved as a matter of urgency because current approaches to controlling ARF/RHD in Aboriginal communities have clearly been ineffective. New understanding of the pathogenesis of ARF would have an immediate effect on primary prevention strategies and vaccine development.

Influence of recombination and niche separation on the population genetic structure of the pathogen Streptococcus pyogenes

The throat and skin of the human host are the principal reservoirs for the bacterial pathogen Streptococcus pyogenes. The emm locus encodes structurally heterogeneous surface fibrils that play numerous roles in virulence, depending on the strain. Isolates harboring the emm pattern A-C marker exhibit a strong tendency to cause throat infection, whereas emm pattern D strains are usually recovered from impetigo lesions; as a group, emm pattern E organisms fail to display obvious tissue tropisms. The peak incidence for streptococcal pharyngitis and impetigo varies with season and locale, leading to wide spatial and temporal distances between throat and skin strains. To assess any impact of niche separation on genetic variation, the extent of recombinational exchange between emm pattern A-C, D, and E subpopulations was evaluated. Analysis of nucleotide sequence data for internal portions of seven housekeeping loci from 212 isolates provides evidence of extensive recombination between strains belonging to different emm pattern subpopulations. Furthermore, no fixed nucleotide differences were found between emm pattern A-C and D strains. Thus, despite some niche separation created by distinct epidemiological trends and innate tissue tropisms there is little evidence for neutral gene divergence between throat and skin strains. Maintenance of a relationship between emm pattern and tissue tropism in the face of underlying recombination suggests that tissue tropism is associated with emm or a closely linked gene.

Rheumatic fever in the 21st century

In the first half of the twentieth century, the group A streptococcus (GAS) was established as the sole etiologic agent of acute rheumatic fever (ARF). In the century's latter half, the clinical importance of variation in the virulence of strains of GAS has become clearer. Although still obscure, the pathogenesis of ARF requires primary infection of the throat by highly virulent GAS strains. These contain very large hyaluronate capsules and M protein molecules. The latter contain epitopes that are cross-reactive with host tissues and also contain superantigenic toxic moieties. In settings where ARF has become rare, GAS pharyngitis continues to be common, although it is caused by GAS strains of relatively lower virulence. These strains, however, colonize the throat avidly and stubbornly. Molecularly distinct pyoderma strains may cause acute glomerulonephritis, but they are not rheumatogenic, even though they may secondarily colonize and infect the throat. Guidelines for the diagnosis, treatment, and prevention of GAS pharyngitis and ARF are reviewed with particular reference to the prevalence of the latter in the community.

Immunogenic and Genetic Factors in Rheumatic Fever

Although rheumatic fever has virtually disappeared in many developed countries, it remains the number one acquired heart disease among children in developing countries. Many hypotheses advanced to explain the pathogenic mechanisms of this disease include the concept of an abnormal humoral and cellular response within the host to streptococcal antigens cross-reacting with mammalian tissues. This report examines the most recent evidence supporting this concept. It emphasizes the importance of the cellular arm of the immune response in cardiac damage, as wall as possible genetic disposition to the disease.

Rheumatic chorea in northern Australia: a clinical and epidemiological study

To describe the epidemiology and clinical features of Sydenham's chorea in the Aboriginal population of northern Australia a review was conducted of 158 episodes in 108 people: 106 were Aborigines, 79 were female, and the mean age was 10.9 years at first episode. Chorea occurred in 28% of cases of acute rheumatic fever, carditis occurred in 25% of episodes of chorea, and arthritis in 8%. Patients with carditis or arthritis tended to have raised acute phase reactants and streptococcal serology. Two episodes lasted at least 30 months. Mean time to first recurrence of chorea was 2.1 years compared with 1.2 years to second recurrence. Established rheumatic heart disease developed in 58% of cases and was more likely in those presenting with acute carditis, although most people who developed rheumatic heart disease did not have evidence of acute carditis with chorea. Differences in the patterns of chorea and other manifestations of acute rheumatic fever in different populations may hold clues to its pathogenesis. Long term adherence to secondary prophylaxis is crucial following all episodes of acute rheumatic fever, including chorea, to prevent recurrence.

Rheumatic fever. The relationships between host, microbe, and genetics

Acute rheumatic fever is a delayed, nonsuppurative sequela of a pharyngeal infection with the group A streptococcus. The onset of the disease is usually characterized by an acute febrile illness; however, there may be chronic involvement of the heart and/or central nervous system. The article explores the relationship between the initial infection and host-microbial interactions that may be operative in disease pathogenesis.

Outbreak of acute glomerulonephritis in children: observed association with the T1 subtype of group A streptococcal infection in northern Kyushu, Japan

Group A streptococcal infection is associated with the occurrence of acute glomerulonephritis (AGN) and rheumatic fever (RF). A surveillance study in the Saga area, in northern Kyushu, Japan, showed a small variation in the reported number of group A streptococcal infections in the period 1988-94. However, of the AGN cases reported in this period, more than half were observed in 1992. In order to examine whether some change had occurred in the serotype distribution of Streptococcus pyogenes during the period, patients in the Saga area diagnosed as having group A streptococcal infection and patients with AGN or RF were analyzed. Serological T-typing of S. pyogenes was carried out for patients with group A streptococcal infections, and the association between the occurrence of AGN or RF and the distribution of each different T subtype was analyzed. M-typing of S. pyogenes was also carried out and the correlation between T and M types was examined. From 1988 to 1994, the annual number of patients with group A streptococcal infections in the Saga area showed a small variation, range 65-100 patients/year. Of the 42 patients with AGN and three with RF observed in this period, 27 with AGN (64%) and one with RF (33.3%) were detected in 1992. Only the T1 subtype increased in 1992; the other T subtypes showed little variation in incidence. The number of patients with the T1 subtype was significantly correlated with the occurrence of AGN by regression analysis (P < 0.01). Of the 170 subjects tested for both T and M subtypes, 44 of the 45 T1-typed subjects had the M1 protein. Our epidemiological study suggested that the T1 subtype of streptococcal infection was associated with an outbreak of AGN in 1992 in the Saga area.

Acute rheumatic fever and rheumatic heart disease in the top end of Australia's Northern Territory

OBJECTIVE

To describe the epidemiological and clinical features of acute rheumatic fever and rheumatic heart disease in the Top End of the Northern Territory.

METHODS

A retrospective review (in some instances as far back as the 1960s) of all cases of known or suspected acute rheumatic fever or rheumatic heart diseases, with prospective validation of clinical status where necessary. Cases were ascertained from hospital and community medical clinic records and medical staff; and from records and health staff of 10 rural communities.

RESULTS

Three hundred and eighty-six revised Jones criteria-confirmed episodes of acute rheumatic fever were documented in 249 individuals (99% Aboriginal). The annual incidence of confirmed acute rheumatic fever between 1989 and 1993 was 254 per 100,000 Aboriginal people aged 5 to 14 years. A more accurate estimate of 651 per 100,000 came from 10 rural communities with more complete information. As of 1995, there were 286 people living with established rheumatic heart disease (95% Aboriginal). The point prevalence of rheumatic heart disease among Aboriginal people was 9.6 per 1000, with a rate of 24 per 1000 in one large rural community. Sydenham's chorea was common, and associated with later rheumatic heart disease in 49% of cases. There was a preponderance of females with acute rheumatic fever, rheumatic heart disease and chorea.

CONCLUSIONS

In Aboriginal people in rural northern Australia the incidence of acute rheumatic fever is higher than that reported anywhere in the world, and the prevalence of rheumatic heart disease is among the highest in the world. While continuing attention must be paid to alleviating the causes of these diseases of poverty, immediate action is needed to improve diagnosis of acute rheumatic fever, adherence to secondary benzathine penicillin prophylaxis regimens, and follow-up of rheumatic heart disease cases.

A one-year study of streptococcal infections and their complications among Ethiopian children

Post-streptococcal complications are known to be common among Ethiopian children. Little is known, however, about the epidemiology of beta-haemolytic streptococci in Ethiopia. A total of 816 children were studied during a one-year period: 24 cases of acute rheumatic fever (ARF), 44 chronic rheumatic heart disease (CRHD), 44 acute post streptococcal glomerulonephritis (APSGN), 143 tonsillitis, 55 impetigo, and 506 were apparently healthy children. Both ARF and APSGN occurred throughout the year with two peaks during the rainy and cold seasons. The female:male ratio among ARF patients was 1.4:1 and 1:1.9 among APSGN. The monthly carrier rate of beta-haemolytic streptococci group A varied from 7.5-39%, average being 17%. T type 2 was the most frequent serotype. Marked seasonal fluctuations were noted in the distribution of serogroups among apparently healthy children. Beta-haemolytic streptococci group A dominated during the hot and humid months of February-May. Strains were susceptible to commonly used antibiotics, except for tetracycline.

Heptad motifs within the distal subdomain of the coiled-coil rod region of M protein from rheumatic fever and nephritis associated serotypes of group A streptococci are distinct from each other: nucleotide sequence of the M57 gene and relation of the deduced amino acid sequence to other M proteins

Streptococcal M protein, a dimeric alpha helical coiled-coil molecule, is an antigenically variable virulence factor on the surface of the bacteria. Our recent conformational analysis of the complete sequence of the M6 protein led us to propose a basic model for the M protein consisting of an extended central coiled-coil rod domain flanked by a variable N-terminal and a conserved C-terminal end domains. The central coiled-coil rod domain of M protein, which constitutes the major part of the M molecule, is made up of repeating heptads of the generalized sequence a-b-c-d-e-f-g, wherein "a" and "d" are predominantly apolar residues. Based on the differences in the heptad pattern of apolar residues and internal sequence homology, the central coiled-coil rod domain of M protein could be further divided into three subdomains I, II, and III. The streptococcal sequelae rheumatic fever (RF) and acute glomerulonephritis (AGN) have been known to be associated with distinct serotypes. Consistent with this, we observed that the AGN associated M49 protein exhibits a heptad motif that is distinct from the RF associated M5 and M6 proteins. Asn and Leu predominated in the "a" and "d" positions, respectively, in subdomain I of the M5 and M6 proteins, whereas apolar residues predominated in both these positions in the M49 protein. To establish whether the heptad motif of M49 is unique to this protein, or is a general characteristic of nephritis-associated serotypes, the amino acid sequence of M57, another nephritis-associated serotype, has now been examined. The gene encoding M57 was amplified by PCR, cloned into pUC19 vector, and sequenced. The C-terminal half of M57 is highly homologous to other M proteins (conserved region). In contrast, its N-terminal half (variable region) revealed no significant homology with any of the M proteins. Heptad periodicity analysis of the M57 sequence revealed that the basic design principles, consisting of distinct domains observed in the M6 protein, are also conserved in the M57 molecule. However, the heptad motif within the coiled-coil subdomain I of M57 was distinct from M5 and M6 but similar to M49. Similar analyses of the heptad characteristics within the reported sequences of M1, M12, and M24 proteins further confirmed the conservation of the overall architectural design of sequentially distinct M proteins.(ABSTRACT TRUNCATED AT 400 WORDS)

Changing perspectives in children hospitalized with poststreptococcal acute glomerulonephritis

Changing perspectives in 95 children with poststreptococcal acute glomerulonephritis (PSAGN) in our hospital between 1979 and 1988 are reported. Between 1961 and 1970 an average of 31 +/- 6.3 patients/year with PSAGN were treated and 70% had antecedent pyoderma. In the present study antecedent pharyngitis was observed in 59 children and pyoderma in 36. In comparison to the decade ending in 1970 our data show: (1) a marked decline in the prevalence of PSAGN (P = less than 0.0005), (2) a predominance of antecedent pharyngeal infection (P = 0.044), (3) a decline in urban and an increase in rural patients with PSAGN (P = 0.0483); and in the last decade: (1) a predominance of antecedent pharyngeal infection in children over 6 years of age (P = 0.0009) and (2) a predominance of antecedent pyoderma in black children (P = 0.0004).

Differentiation of patients with rheumatic fever from those with inactive rheumatic heart disease using the artificial subcutaneous nodule test, myocardial reactive antibodies, serum immunoglobulin and serum complement levels

Thirty patients with acute rheumatic fever, and 20 with inactive rheumatic heart disease were studied in order to determine parameters which differentiate the two groups. Subcutaneous nodules developed following the subcutaneous injection of autologous blood in 16 of 26 patients with rheumatic fever but in none of the 20 with inactive rheumatic heart disease (P = 0.00001). Myocardial reactive antibodies were found in 14 of 30 patients with rheumatic fever, and in 4 of 20 with inactive rheumatic heart disease (P = 0.0505). Significantly higher values of IgG (P less than 0.001), IgA (P less than 0.01), C3 (P less than 0.001) and C4 (P less than 0.001) were observed in rheumatic fever patients. There was no significant difference in IgM levels. A combination of three variables (artificial subcutaneous nodules, IgA, and C3) had a sensitivity of 87% and a specificity of 100% for rheumatic fever. A combination of two variables (artificial subcutaneous nodules and IgA) had a sensitivity of 84% and a specificity of 100% for rheumatic fever.

The concurrent associations of group A streptococcal serotypes in children with acute rheumatic fever or pharyngitis-associated glomerulonephritis and their families in Kuwait

A group of 146 children with acute rheumatic fever and 256 members from their families, and a group of 125 children with post-streptococcal glomerulonephritis and 199 family members, together with a group of 145 children with non-complicated group A streptococcal pharyngitis were examined over a period of three years. The purpose of the study was to explore the concurrent association and distribution of group A streptococcal serotypes among the three groups. Strains isolated from the children with non-complicated group A streptococcal pharyngitis represented the prevalent strains of group streptococci in the childhood community during the period of study. Rheumatic fever was encountered in a non epidemic situation. As expected, the recovery of group A streptococci was low. The strains however belonged mainly to two patterns, namely type M1 and M non-typable strains. Nephritis was pharyngitis-associated and occured also sporadically throughout the year. Types M12 and 49 accounted for the majority of the isolates. Type M12 accounted for 34.4% of the group A isolates from family members of children with nephritis and was totally absent in family members of children with rheumatic fever (p less than 0.001). The T pattern 8/25/Imp. 19 accounted for 40% of the group A isolates from family members of rheumatic patients compared to 3.3% from family members of nephritis patients (p less than 0.005). Data from this study show that the group A streptococcal serotypes, concurrently isolated from children with acute rheumatic fever and their families are disparately different from those of children with pharyngitis-associated glomerulonephritis and their families in the same population. These findings support the concept of "nephritogenicity" and "rheumatogenicity" and indicated the important role of the biological characteristics of the streptococcal serotypes in the aetiology of acute rheumatic fever and acute poststreptococcal glomerulonephritis.

Streptococcal neuraminidase and acute glomerulonephritis

We examined the hypothesis that streptococcal neuraminidase may alter host serum immunoglobulin G so that autoantibodies are formed which lead to immune complexes and acute glomerulonephritis. We confirmed the observation that T-type 4 and T-type 12 streptococci (both associated with acute glomerulonephritis) are the most likely of many types studied to produce neuraminidase. However, we did not find this enzyme to be produced by any of 23 streptococcal strains isolated from patients with nephritis, whereas it was produced by two strains from patients with rheumatic fever and by one strain from a patient with scarlet fever. Also, we were unable to find direct or indirect evidence of increased neuraminidase activity in the sera of six patients with acute glomerulonephritis when they were compared with the sera of six patients with acute rheumatic fever and with those of six normal subjects.

Type-specific antibodies to structurally defined fragments of streptococcal M proteins in patients with acute rheumatic fever

Group A streptococci of M protein type 5 have been epidemiologically related to acute rheumatic fever in a number of reported outbreaks. Preliminary bacteriological evidence suggests that M5 may be an important "rheumatogenic" type in Santiago, Chile. To assess further the relationship of this streptococcal serotype to rheumatic fever in Chile, sera of 34 patients with rheumatic fever and an equal number of age-, sex-, and race-matched controls were assayed for antibodies to types 5, 6, and 24 in an enzyme-linked immunosorbent assay with purified pepsin extracts of the respective M proteins as solid-phase antigens. Sera of 11 rheumatic fever patients (32%) were positive (titer greater than 1:800) for type 5 antibodies, but only 1 (3%) of the matched controls was positive (P less than 0.01). Neither the patients nor the controls had antibodies to type 24. Although 38% of the patient sera contained antibodies to type 6, 29% of the control sera also had such antibodies (P greater than 0.20). The enzyme-linked immunosorbent assay served as an accurate predictor of which sera contained type 5 opsonic antibodies as measured by the opsonophagocytic test. Although antigenic cross-reactivity exists between M protein type 5 and type 6 group A streptococci, this phenomenon is unlikely to have accounted for the preferential occurrence of type 5 antibodies in rheumatic fever sera. The enzyme-linked immunosorbent assay and opsonic antibody results suggest that M5 is an important rheumatogenic type in Chile.

The antistreptococcal immune responses in children with acute rheumatic fever in Kuwait

The antistreptococcal immune responses in 130 children with Acute Rheumatic Fever (ARF), seen in Kuwait, over a period of three years, are presented. The ages of children ranged between three to 13 years. One hundred and three presented in initial attacks while 27 presented in recurrences. The geometric mean of antistreptolysin 'O' (ASO) and antihyalurodinase (AH) titres for all patients were 488 Todd Units and 595 units, respectively. In children under the age of eight years, but not above this age, the geometric mean of ASO titres was significantly higher in children with carditis than in those without carditis (P less than 0.01); there was no significant difference in AH titres between the two groups. Analysis of the Geometric Mean Titres (GMT) of both antibodies in relation to other variables is also presented.

Serum immunoglobulin A and antibody to M-associated protein in patients with acute glomerulonephritis or rheumatic fever

Serum immunoglobulin A (IgA) was markedly increased in 80% of 50 patients with acute rheumatic fever in Trinidad in contrast to 20% of 63 patients with acute glomerulonephritis, whereas serum IgG was increased in nearly all of both groups. Since total antibody to M-associated protein (MAP) (assessed by complement fixation) is the only antibody as yet consistently found to be of higher titer in patients with acute rheumatic fever than in patients with acute glomerulonephritis in Trinidad, it was measured and the titers were related to serum levels of IgA. The titers of total antibody to MAP were greater than or equal to 40 in 58% of the rheumatic fever patients, 43% of the nephritis patients, and 8% of well school-children. However, its presence in rheumatic fever patients did not correlate directly with amounts of serum IgA present (r = 0.0507). Moreover, titers of total antibody to MAP related equally well to enzyme-linked immunosorbent assay indicated amounts of IgG antibody (r = 0.3939) and IgA antibody (r = 0.3054) to MAP in rheumatic fever patients but not in nephritis patients (r = 0.0301 for IgA antibody and 0.6909 for IgG antibody to MAP), whereas they related best to IgM antibody to MAP in the school-children (r = 0.4204).