Increasing incidence of invasive group A streptococcus disease in New Zealand, 2002–2012: A national population-based study
Introduction
Group A streptococcus (GAS) is a major human pathogen, and infections with GAS are associated with considerable global morbidity and mortality.1, 2 Acute clinical manifestations of GAS disease range from pharyngitis and superficial skin infections through to severe invasive syndromes such as necrotizing fasciitis, puerperal sepsis, bacteraemia and streptococcal toxic shock syndrome.2, 3 Moreover, the non-suppurative immunological sequelae of GAS infection (rheumatic fever, rheumatic heart disease and post-streptococcal glomerulonephritis) result in a significant clinical and economic disease burden.4, 5
The incidence of invasive GAS disease varies both temporally and geographically.6, 7, 8, 9, 10 In most developed countries, the reported incidence of invasive GAS disease is between 2 and 4 cases per 100,000 population.3 However, a previous study in Auckland, New Zealand suggested that the incidence of invasive GAS disease (8.1 per 100,000 population) was considerably higher in New Zealand compared to similar developed countries.11 In addition, these authors described notable disparity in incidence rates, with the highest incidence in Māori (indigenous New Zealander) and Pacific peoples.11
Contemporary molecular typing of GAS is carried out by sequence analysis of the hypervariable region of the emm gene.12 This gene encodes the M-protein, a major virulence factor of GAS, involved in adhesion to host tissues and immune evasion.13 To date, the most clinically advanced GAS vaccine candidates are those that target the N-terminal region of the M-protein. A 26-valent M-protein demonstrated good safety and immunogenicity in Phase I and II clinical trials,14 and subsequently, a 30-valent vaccine has recently been developed to increase serotype coverage.15, 16 However, a prerequisite for success of these M-protein based vaccines is adequate coverage of locally circulating GAS emm types.
To date, longitudinal changes in the relative proportions of circulating emm types associated with invasive GAS disease have only rarely been described.17 In addition, no studies have systematically assessed temporal trends in the epidemiology of invasive GAS disease in New Zealand. Accordingly, we sought to: (i) describe the incidence, trends and demographics of invasive GAS disease in New Zealand over an 11-year period and (ii) to describe the molecular epidemiology of circulating GAS emm types associated with invasive GAS disease.
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Setting, patients and isolates
New Zealand is an island nation in the South West Pacific, with a resident population of approximately 4.4 million. The country is ethnically diverse, consisting of the following main ethnicities: 67% European, 15% Māori, 10% Asian, 7% Pacific peoples and 1% of other ethnicities.
Unlike acute rheumatic fever, invasive GAS disease is not a notifiable condition in New Zealand. Consequently, surveillance of invasive GAS infection is predominantly passive and laboratory-based, depending on
Number, incidence and outcomes of invasive GAS infections
Applying our case definition, a total of 2861 invasive GAS infections were identified over the study period. Of these, 2755 infections (96%) were based on isolation from a sterile site: 2535 (92%) from blood, 159 (6%) bone and joint, 26 (1%) from pleura, 19 (0.5%) from cerebrospinal fluid, 15 (0.5%) from peritoneal fluid, and one isolate from pericardial fluid. Of the remaining 105 cases in which a GAS isolate had no anatomical site specified, 75 had an ICD-10 hospital discharge code of M725
Discussion
In this study, we analysed the trends and demographics of invasive GAS disease in the New Zealand population between 2002 and 2012. The incidence of invasive GAS infections approximately doubled over the study period from 3.9 per 100,000 population in 2002 to 7.9 per 100,000 population (P < 0.001) in 2012. In addition, we observed notable sociodemographic variation in the incidence of invasive GAS disease, with the highest rates in Pacific peoples and Māori populations, and in those patients
Funding
This study was supported by funding from the New Zealand Ministry of Health.
Acknowledgements
We thank all diagnostic microbiology laboratories throughout New Zealand for sending GAS isolates to ESR, and physicians involved in the care of these patients.
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Necrotising soft-tissue infections
2023, The Lancet Infectious DiseasesCitation Excerpt :An increased incidence of necrotising soft-tissue infections, group A streptococcus-associated or not, has been reported in the last decades worldwide.7,11,14,18,20,21 Data are best established for necrotising soft-tissue infections caused by group A streptococcus, as active surveillance of invasive group A streptococcus infection exists in several countries.20–31 Prospective population-based studies report invasive group A streptococcus infection incidence to be 3–4 per 100 000 person-years, although incidence might be five-to-ten-times higher among indigenous populations or in tropical countries.23
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2021, International Journal of Infectious DiseasesCitation Excerpt :Ethnic disparities exist, with Indigenous Māori and Pacific peoples having 24 cases per 100 000 per person per year (Safar et al., 2011). The incidence of invasive GAS infections appears to be increasing in NZ and other settings, including in Europe and Australia (Carapetis et al., 2005; Efstratiou and Lamagni, 2016; Oliver et al., 2018; Williamson et al., 2015). GAS infection can also lead to the development of immune-mediated sequelae, namely acute rheumatic fever (ARF) and acute post-streptococcal glomerulonephritis (APSGN).