Invasive Group A Streptococcal Infection in Children, 1992-2023

Area of Science:

• Infectious Diseases
• Epidemiology
• Microbiology

Background:

• Resurgence of invasive group A streptococcal (iGAS) infections highlights the need for updated epidemiological data.
• Progress in group A streptococcal (GAS) vaccine development necessitates understanding current iGAS trends.

Purpose of the Study:

• To describe the epidemiology of pediatric iGAS infections over a 32-year period in Toronto and Peel Region, Canada.
• To analyze trends in incidence, clinical presentation, disease severity, emm types, and antimicrobial resistance of pediatric iGAS.

Main Methods:

• Population-based surveillance data for iGAS cases in children (<18 years) from 1992 to 2023.
• Inclusion of emm typing data and Canadian population statistics.
• Analysis of disease incidence, clinical features, outcomes, emm types, and antimicrobial resistance.

Main Results:

• Overall incidence of pediatric iGAS increased from 1.8 to 2.4 per 100,000 population (1992-2011 vs. 2012-2019), driven by respiratory infections.
• Incidence declined in 2020-2021 but surged to 6.0 per 100,000 in 2023, with viral respiratory coinfections noted in 32% of cases in 2022-2023.
• emm1 was the most common type (38.6%), associated with higher rates of pneumonia, bone/joint infections, and ICU admission. M1UK subtype emerged in 2019.
• Varicella-associated iGAS cases significantly declined post-vaccination implementation (16.8% in 1992-2001 to 0.9% in 2012-2023).
• Severe outcomes included streptococcal toxic shock syndrome (5.8%), necrotizing fasciitis (2.4%), and a 2.0% mortality rate.

Conclusions:

• Pediatric iGAS incidence in south-central Ontario rose pre- and post-COVID-19 pandemic, linked to respiratory infections and viral coinfections.
• Different emm types are associated with distinct clinical presentations and disease severity.
• The majority of circulating emm types are covered by the current 30-valent GAS vaccine candidate.