Invasive group A streptococcal (iGAS) surveillance in Island Health, British Columbia, 2022

Area of Science:

• Infectious Diseases
• Epidemiology
• Public Health Surveillance

Background:

• Invasive group A streptococcal disease (iGAS) is a serious infection caused by *Streptococcus pyogenes*.
• Increased iGAS alerts in Island Health in 2022 prompted local epidemiological investigation.
• Global trends showed rising paediatric iGAS infections, necessitating a review of regional data.

Purpose of the Study:

• To summarize the epidemiological trends of iGAS in the Island Health region for 2022.
• To compare 2022 iGAS data with historical surveillance data from 2017-2021.
• To identify demographic and microbiological characteristics of iGAS cases.

Main Methods:

• A passive surveillance system collected data on laboratory-confirmed iGAS cases in Island Health.
• Data from 2022 were analyzed and compared to historical data (2017-2021).
• Epidemiological rates, age distribution, sex, *emm* types, and clinical outcomes were examined.

Main Results:

• The 2022 iGAS incidence rate was 11.4 cases per 100,000 population, the highest in six years.
• The highest risk group was males aged 40-59 years (21.3 cases per 100,000).
• Hospitalization was common (85%), with significant ICU admission (21%) and mortality (6%).

Conclusions:

• iGAS incidence in Island Health increased throughout the COVID-19 pandemic, peaking in 2022.
• Unlike international reports, no significant rise in paediatric iGAS cases was observed locally.
• Continued regular monitoring of iGAS epidemiology is crucial due to sustained high activity.