Group A Streptococcal Disease Invasive (iGAS)

Group A streptococcus is a bacterium that people may carry in their nose, throat or on their skin without symptoms.
If GAS does cause symptoms, most of the time it only causes mild illness, including strep throat.

Occasionally the bacterium can cause more severe infections. This happens when the bacterium gets into your blood, lungs, or muscles. This is called invasive group A streptococcal infection or iGAS.

The rarest, but most serious forms of iGAS, are:

Streptococcal toxic shock syndrome
Necrotizing fasciitis, often called flesh-eating disease

Local information

2025 Statistics

Incidence rate is the number of new cases of disease divided by the number of persons at risk for the disease during a particular time period.

Cases:
29*

*Includes confirmed cases in 2025.

Incidence rate per 100,000 in 2025: 19.5

Incidence rate per 100,000 of invasive group A streptococcal disease by year

A line graph showing the crude rate and five year moving average of Invasive Group A Streptococcal disease by year within the Health Unit region between 2016 and 2025.

Data sources

Case counts (2016-2025), population estimates (2016-2023), & population projections (2024-2025): Public Health Ontario.
Query: Case counts of reportable diseases by public health unit and year. Toronto, ON: Ontario Agency for Health Protection and Promotion; extracted on March 9, 2026.

More information about GAS

Group A streptococcus disease fact sheet

Reporting

Report to the Health Unit immediately by fax (705-482-0670) and phone at 705-474-1400 or toll free at 1-800-563-2808, ext. 5229 if iGAS is suspected or confirmed as per Ontario Regulation 135/18 and amendments under the Health Protection and Promotion Act, R.S.O., c.H.7.

After hours, weekends, and holidays, call 705-474-1400 then press 0 to speak with the Answering Service. The on-call CDC Public Health Nurse will get back to you as soon as possible.

Should one go to childcare, school, or work if they have iGAS?

Individuals with confirmed streptococcal pharyngitis, especially school-aged children, should remain at home until at least 24 hours after beginning and complying with appropriate antimicrobial therapy.
Follow the direction of your healthcare provider, public health case manager, or occupational health at your workplace.

Healthcare provider fnformation

Contact the Communicable Disease Control (CDC) program at 705-474-1400 or toll free at 1-800-563-2808, ext. 5229, or by email to cdc@healthunit.ca for more information.

Last updated: Apr 2026, by CDC

Group A Streptococcal Disease, Invasive (iGAS)