Aggressive, often deadly form of strep hits record-high case numbers in Canada

Canada is seeing a record number of cases of invasive Group A strep, a bacterial infection that kills roughly one in 10 people who contract it, according to data obtained by CBC News. 

More than 4,600 cases were confirmed in 2023 at the National Microbiology Lab in Winnipeg, an increase of more than 40 per cent over the previous yearly high, in 2019, says the Public Health Agency of Canada. 

This trend emerges as a new report from Public Health Ontario shows six children have died of invasive Group A strep in the province since October.

Over the final three months of 2023, the number of cases in Ontario and hospitalizations from the disease were nearly double those during the same time period the previous year, says the report. 

That's prompting warnings from public health officials and medical experts about the potential severity of the disease. 

"Whenever you see invasive group A strep, you have to be worried because usually the patient is quite sick," said Dr. Donald Vinh, head of infectious diseases at McGill University Health Centre in Montreal. 

"This is a serious infection and a potentially deadly one," Vinh said in an interview.  

Invasive Group A streptococcal disease happens when the common strep A bacteria spreads beyond the places it typically infects (such as the throat or skin) into sterile parts of the body, such as the bloodstream or the liquid around the brain, or into soft tissue, where it can cause necrotizing fasciitis, known as flesh-eating disease. 

The latest report from Public Health Ontario on invasive Group A strep tallies 48 deaths from October to December, including six among children aged nine or younger. 

"We're monitoring this very closely," said Dr. Liane Macdonald, a public health physician in the agency's health protection section. 

Dr. Brian Conway, medical director of the Vancouver Infectious Diseases Centre, describes the Ontario figures as very concerning. 

"We need to understand why it happened, compare what's going on in Ontario to what we're seeing in the rest of the world and design a strategy to address it," Conway said in an interview. 

WATCH | Invasive form of strep A hitting record highs in Canada:

Ontario's data show roughly three-quarters of people with a confirmed case of invasive Group A strep end up admitted to hospital. In the years leading up to the COVID-19 pandemic, around 10 per cent of cases resulted in death, although the rate differs among different age groups, tending to be higher in seniors.