Continued high caseload of rheumatic fever in western Pennsylvania: Possible rheumatogenic emm types of streptococcus pyogenes

Global Streptococcus pyogenes strain diversity, disease associations, and implications for vaccine development: a systematic review

The high strain diversity of Streptococcus pyogenes serves as a major obstacle to vaccine development against this leading global pathogen. We did a systematic review of studies in PubMed, MEDLINE, and Embase that reported the global distribution of S pyogenes emm-types and emm-clusters from Jan 1, 1990, to Feb 23, 2023. 212 datasets were included from 55 countries, encompassing 74 468 bacterial isolates belonging to 211 emm-types. Globally, an inverse correlation was observed between strain diversity and the UNDP Human Development Index (HDI; r=-0·72; p<0·0001), which remained consistent upon subanalysis by global region and site of infection. Greater strain diversity was associated with a lower HDI, suggesting the role of social determinants in diseases caused by S pyogenes. We used a population-weighted analysis to adjust for the disproportionate number of epidemiological studies from high-income countries and identified 15 key representative isolates as vaccine targets. Strong strain type associations were observed between the site of infection (invasive, skin, and throat) and several streptococcal lineages. In conclusion, the development of a truly global vaccine to reduce the immense burden of diseases caused by S pyogenes should consider the multidimensional diversity of the pathogen, including its social and environmental context, and not merely its geographical distribution.

Acute Rheumatic Fever

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

Comparison of approaches to rheumatic fever surveillance across Organisation for Economic Co-operation and Development countries

AIM

Rheumatic fever (RF) prevention, control and surveillance are increasingly important priorities in New Zealand (NZ) and Australia. We compared RF surveillance across Organisation for Economic Co-operation and Development (OECD) member countries to assist in benchmarking and identifying useful approaches.

METHODS

A structured literature review was completed using Medline and PubMed databases, investigating RF incidence rates. Surveillance methods were noted. Health department websites were searched to assess whether addressing RF was a Government priority.

RESULTS

Of 32 OECD member countries, nine reported RF incidence rates after 1999. Highest rates were seen in indigenous Australians, and NZ Māori and Pacific peoples. NZ and Australian surveillance systems are highly developed, with notification and register data compiled regularly. Only these two Governments appeared to prioritise RF surveillance and control. Other countries relied mainly on hospitalisation data. There is a lack of standardisation across incidence rate calculations. Israel and Italy may have relatively high RF rates among developed countries.

CONCLUSIONS

RF lingers in specific populations in OECD member countries. At a minimum, RF registers are needed in higher incidence countries. Countries with low RF incidences should periodically review surveillance information to ensure rates are not increasing.

Post-infectious group A streptococcal autoimmune syndromes and the heart

There is a pressing need to reduce the high global disease burden of rheumatic heart disease (RHD) and its harbinger, acute rheumatic fever (ARF). ARF is a classical example of an autoimmune syndrome and is of particular immunological interest because it follows a known antecedent infection with group A streptococcus (GAS). However, the poorly understood immunopathology of these post-infectious diseases means that, compared to much progress in other immune-mediated diseases, we still lack useful biomarkers, new therapies or an effective vaccine in ARF and RHD. Here, we summarise recent literature on the complex interaction between GAS and the human host that culminates in ARF and the subsequent development of RHD. We contrast ARF with other post-infectious streptococcal immune syndromes - post-streptococcal glomerulonephritis (PSGN) and the still controversial paediatric autoimmune neuropsychiatric disorders associated with streptococcal infections (PANDAS), in order to highlight the potential significance of variations in the host immune response to GAS. We discuss a model for the pathogenesis of ARF and RHD in terms of current immunological concepts and the potential for application of in depth "omics" technologies to these ancient scourges.

Cutting edge issues in rheumatic fever

Although the incidence of acute rheumatic fever and rheumatic heart disease has decreased significantly in regions of the world where antibiotics are easily accessible, there remains a high incidence in developing nations as well as in certain regions where there is a high incidence of genetic susceptibility. These diseases are a function of poverty, low socioeconomic status, and barriers to healthcare access, and it is in the developing world that a comprehensive prevention program is most critically needed. Development of group A streptococcal vaccines has been under investigation since the 1960s and 50 years later, we still have no vaccine. Factors that contribute to this lack of success include a potential risk for developing vaccine-induced rheumatic heart disease, as well as difficulties in covering the many serological subtypes of M protein, a virulence factor found on the surface of the bacterium. Yet, development of a successful vaccine program for prevention of group A streptococcal infection still offers the best chance for eradication of rheumatic fever in the twenty-first century. Other useful approaches include continuation of primary and secondary prevention with antibiotics and implementation of health care policies that provide patients with easy access to antibiotics. Improved living conditions and better hygiene are also critical to the prevention of the spread of group A streptococcus, especially in impoverished regions of the world. The purpose of this article is to discuss current and recent developments in the diagnosis, pathogenesis, and management of rheumatic fever and rheumatic heart disease.

Streptococcus pyogenes and re-emergence of scarlet fever as a public health problem

Explosive outbreaks of infectious diseases occasionally occur without immediately obvious epidemiological or microbiological explanations. Plague, cholera and Streptococcus pyogenes infection are some of the epidemic-prone bacterial infections. Besides epidemiological and conventional microbiological methods, the next-generation gene sequencing technology permits prompt detection of genomic and transcriptomic profiles associated with invasive phenotypes. Horizontal gene transfer due to mobile genetic elements carrying virulence factors and antimicrobial resistance, or mutations associated with the two component CovRS operon are important bacterial factors conferring survival advantage or invasiveness. The high incidence of scarlet fever in children less than 10 years old suggests that the lack of protective immunity is an important host factor. A high population density, overcrowded living environment and a low yearly rainfall are environmental factors contributing to outbreak development. Inappropriate antibiotic use is not only ineffective for treatment, but may actually drive an epidemic caused by drug-resistant strains and worsen patient outcomes by increasing the bacterial density at the site of infection and inducing toxin production. Surveillance of severe S. pyogenes infection is important because it can complicate concurrent chickenpox and influenza. Concomitant outbreaks of these two latter infections with a highly virulent and drug-resistant S. pyogenes strain can be disastrous.

Molecular markers for the study of streptococcal epidemiology

Diseases caused by Streptococcus pyogenes (Group A streptococcus, GAS) range from superficial infections such as pharyngitis and impetigo to potentially fatal rheumatic heart disease and invasive disease. Studies spanning emm-typing surveillance to population genomics are providing new insights into the epidemiology, pathogenesis, and biology of this organism. Such studies have demonstrated the differences that exist in the epidemiology of streptococcal disease between developing and developed nations. In developing nations, where streptococcal disease is endemic, the diversity of GAS emm-types circulating is much greater than that found in developed nations. An association between emm-type and disease, as observed in developed countries is also lacking. Intriguingly, comparative genetic studies suggest that emm-type is not always a good predictor of the evolutionary relatedness of geographically distant isolates. A view of GAS as a highly dynamic organism, in possession of a core set of virulence genes that contribute to host niche specialization and common pathogenic processes, augmented by accessory genes that change the relative virulence of specific lineages is emerging. Our inability to definitively identify genetic factors that contribute to specific disease outcome underscores the complex nature of streptococcal diseases.

A dramatic decline in university hospital admissions of acute rheumatic fever in the eastern region of Saudi Arabia

BACKGROUNDS

Acute rheumatic fever (ARF) and its sequel, chronic valvular heart disease are the most important causes for cardiovascular morbidity and mortality worldwide and mainly in developing countries. However, the incidence of ARF has declined in developed countries during the second half of 20th century.

MATERIAL AND METHODS

The case files of all patients admitted as new cases of ARF over ∼11 years and 8 months, both in pediatric and medical departments of a university hospital located in the eastern region of Saudi Arabia were reviewed. The demographic and clinical data and the frequency of the new cases were compared with the data that have been published by us 10 years ago from the same hospital during a similar period of time (11 years and 8 months).

RESULTS

In the current study there was a significant decline in the frequency of admission of cases of ARF as compared to our previous study during a similar period of time, with a frequency rate of 12 cases per 100.000 hospitalizations versus 45 cases per 100.000 hospitalizations, respectively, P < 0.001. Dyspnea and chest pain as clinical features of acute rheumatic carditis (ARC) were less frequent in the current study as compared to the previous study (35% versus 44%, P = 0.02 and 10% versus 28.6%, P = 0.031). The subgroup analysis revealed also a decreased frequency of the clinical features of ARC in pediatric age group in the current study as compared to our previous study.

CONCLUSION

There is a significant decline in the frequency of new hospital admissions due to ARF. This decline was associated with similar decline in the frequency of the manifestations of ARC especially in pediatric age group (1-12 years).

No demonstrable effect of benzathine penicillin on recurrence of rheumatic Fever in pacific island population

Compliance with secondary antibiotic prophylaxis for acute rheumatic fever (ARF) should decrease the rate of recurrence; however, efficacy in a highly endemic area has not been studied. A retrospective chart review of patients <21 years old with a diagnosis of ARF in the Northern Mariana Islands was performed. Patient compliance with benzathine penicillin G (BPG) prophylaxis was assessed. One hundred forty-four patients with ARF were identified and considered eligible, and the recurrence rate was 38%. Mean level of compliance with BPG was 59% in patients with no recurrence of ARF and 57% in patients with recurrence of ARF. Level of compliance was not shown to be associated with odds of recurrence. There was a trend toward significance (p = 0.06), with those patients who had carditis at the time of diagnosis of ARF having higher odds of recurrence. A remarkably high recurrence rate of ARF was found in this population, but there was no difference in compliance with secondary antibiotic prophylaxis between those with and without recurrence of ARF. These findings stress the need to improve methods of primary prevention and secondary antibiotic prophylaxis for ARF.

[Acute rheumatic fever: 27 year experience from the Montreal's pediatric tertiary care centers]

OBJECTIVES

To examine the epidemiology, clinical characteristics and outcomes in a cohort of children with acute rheumatic fever (RF) over the past 27 years in Montreal.

METHODS

The medical records of patients younger than 18 years of age hospitalized and diagnosed with RF in Montreal between January 1979 and December 2005 were reviewed.

RESULTS

Among the initial 134 charts selected, 36 children were already followed-up for chronic RF and the remaining 98 patients (51 % females) who fulfilled the Jones criteria for acute RF were included in the analysis. The mean age at diagnosis was 10.1 +/- 3.0 years (range: 3-17). Over the 27-year study period, there was a mean incidence of 3.6 patients/year without peaks, but onset occurred in the last 15 years in almost two-thirds of the patients. Forty-nine percent of the patients were Canadian-born non-aboriginal (CbnA) and the remaining patients were Canadian-born aboriginal (CbA) or foreign-born (Fb). Carditis was diagnosed in 73 % of the patients and Sydenham's chorea in 49 %. Of the CbnA children, 39 % had carditis compared with 61 % of children from other ethnic groups (P = 0.003). However, the form of presentation was chorea in 69 % of CbnA children vs. 31 % of children from other ethnic groups (P < 0.001). No deaths were attributable to acute RF although 2 % of the patients relapsed during the study period. Severe cardiac sequelae requiring valve replacements occurred in 6.1 %.

CONCLUSION

The incidence of acute RF in Montreal was low but consistent over the 27-year study period. Clinical presentation varied depending on ethnicity.