Spike in severe illness caused by strep A bacteria is 'global phenomenon' — including in Canada

As various countries continue to report high levels of invasive group A streptococcal (iGAS) infections — which cause severe illness, and in rare cases death within days — Canadian physicians are also raising alarms over a rise in serious cases this season.

The infections are linked to a common, often-harmless bacteria known as group A streptococcus. Usually it's known for milder illnesses like strep throat or scarlet fever, which are typically treated with antibiotics. 

But when bacteria enter the blood or deep tissue, people can develop more invasive, life-threatening conditions such as necrotizing fasciitis or toxic shock syndrome. In those dire cases, complications can involve massive damage to the skin and soft tissues, leading to amputations or even death, sometimes in as little as 12 to 24 hours after infection. 

In Quebec, the number of iGAS infections recently spiked 56 per cent compared to the pre-pandemic average for the same time period, according to data collected by the province's Ministry of Health and Social Services (MSSS).

A total of 327 cases were reported between the end of August 2022 and Feb. 11, 2023, compared to an average of 223 for the same period between 2015 and 2019, before widespread public health measures during the COVID-19 pandemic kept a variety of infectious diseases at bay. 

The province has also reported multiple deaths among both seniors and children.

While cases peaked late last year, infected children are still coming in at a "steady pace" to Sainte-Justine University Health Centre in Montreal, said pediatric infectious diseases specialist Dr. Fatima Kakkar.

It's the most stressed the hospital has been during a strep A season than any point in the last decade, she added. 

Kakkar points to a lack of immunity among children, with more kids now catching strep recently after avoiding the bacteria over the last few years, coupled with a similar return of influenza in late 2022 after a lengthy lull. 

"What usually happens is a few weeks after [having influenza] or other virus, that's when that strep that might be there in the throat becomes invasive," she explained.

The latest available Ontario data showed this has been a challenging strep season in that province as well, with more than 500 cases reported by the end of February and a higher incidence rate across all age groups than during the same period in the last five years before COVID-19 hit. 

Early findings provided by the Public Health Agency of Canada (PHAC) also suggest a rise in country-wide iGAS cases last November among children under 15, compared to pre-pandemic — though the cases have since returned to typical levels. 

And the challenges go beyond any one province or country.

"I will say it's actually a global phenomenon," said Dr. Susy Hota, the medical director of infection prevention and control with the University Health Network in Toronto. "This is not just a North American thing."