Invasive Group A strep cases rising, but the reason is a medical mystery

Health experts are still trying to understand why the common strep A bacteria that lives all around us sometimes turns invasive, leading to rare but devastating infections.

A year after losing both legs and an arm, a Winnipeg mom has no idea why infection struck

Despite losing both legs and one arm to flesh-eating disease caused by an invasive Group A streptococcal infection, Cari Kirkness tries to live as normally as possible with her 12-year-old son Chaz (left), her three-year-old son Andrew, and her parents. (Tyson Koschik/CBC)

It's been just over a year since a common type of bacteria that lives all around us — usually harmlessly — changed Cari Kirkness's life forever. 

"My body was aching. I had a sore throat, headache, fever," the Winnipeg mother of two, now 29, remembers. 

Kirkness thought she had the flu and went to a walk-in clinic. Without apparent serious symptoms, she was sent home to rest. 

But a bump on her arm was forming, and "it was just getting worse within the hour." 

She went to her local hospital, where emergency department staff realized they were dealing with necrotizing fasciitis — more commonly known as flesh-eating disease — caused by invasive Group A streptococcus bacteria. 

Kirkness was rushed to Winnipeg Health Sciences Centre, where surgeons gave her a terrifying prognosis. In order to save her from the life-threatening infection, they would have to amputate her arm.

Cari Kirkness lost an arm and both legs to invasive Group A strep

4 years ago
Duration 0:38
She knew surgeons would have to remove her arm after becoming infected with flesh-eating disease caused by invasive Group A strep. She didn't know she would end up losing both legs, too.

But while Kirkness was still unconscious after her arm was removed, the infection continued to ravage her body. Doctors told her parents, Tom and Loretta Kirkness, that the only hope of saving their daughter was to amputate both her legs. 

They did, and for 12 excruciating days, Cari's parents, sister, and two sons prayed she would pull through as she lay unconscious in her hospital bed. When she finally woke up on Feb. 20, 2017, her parents rushed to her side — ecstatic that Cari was alive, but forced to break the devastating news that her legs were gone.

"It was a shock," Cari Kirkness remembers. "But when my mom had told me that it was to save my life, that's when I was OK with it."

"She was telling me that God had saved my arm because I can hold my babies. I could hug them."

Kirkness lives with her "babies" — Chaz, 12, and three-year-old Andrew — and her parents in a one-level house they bought, with the help of donations, to accommodate the wheelchair she now relies on.

Loretta Kirkness says she was in 'total shock' when she found out her daughter had flesh-eating disease. (Tyson Koschik/CBC)

To this day, Kirkness and her family have no idea how — or why — the infection happened.  Neither do the doctors and nurses who treated her. 

"[I] didn't really get a definite answer. It was just something freaky, is what I get a lot of people say[ing], like in the medical field," Loretta Kirkness said. 

That's because, as several health experts acknowledged to CBC News, strep A bacteria is still somewhat of a medical mystery. 

Public concern about strep A bacteria escalated in early March, after Markham-Stouffville Hospital, just north of Toronto, confirmed there had been three cases of infection in its childbirth unit in February and that a mother had died from a severe form of it. 

Group A streptococcus is a common bacteria that exists everywhere, including inside people's noses and mouths and on skin wounds, said Dr. Isaac Bogoch, an infectious disease specialist at University Health Network in Toronto.  People often don't even know it's there.

Strep A is transmitted through direct contact with the bacteria, including coughing, sneezing or touching a wound. When strep A makes people sick, it's usually nothing more serious than strep throat. 

But in rare cases, the bacteria becomes "invasive," entering parts of the body where it doesn't normally go, including the bloodstream, muscles and organs. 

That causes serious infections — the most severe of which are flesh-eating disease and streptococcal toxic shock syndrome. Both can be fatal. Treatment includes antibiotics and sometimes surgical removal of infected tissue. 

Number of cases doubles

Although the invasive form of strep A is rare, the number of reported cases in Canada has been rising steadily over the last 15 years, according to data from the Public Health Agency of Canada and from provincial and territorial public health departments.

In 2002, there were 866 reported cases across the country. By 2017, that number more than doubled to at least 2,178 cases (that total does not include Alberta, New Brunswick, Nova Scotia, Nunavut, P.E.I. or Yukon, whose numbers weren't available.) 

More than 100 people died of an invasive Group A strep infection in Canada in 2017, according to information provided by provincial and territorial public health agencies to CBC News.   

Public health experts, including the Public Health Agency of Canada, say they don't know why the numbers are rising and that they continue to investigate. They also don't know exactly what makes common strep A  bacteria turn into a destructive invader of the body.     

"This is an area of active study in the research community," a spokesperson for Health Canada told CBC News in an email.   

That research is producing some theories, Bogoch said. 

"Probably, some of it is related to the bacteria itself," he said. "There can be many strains of the bacteria and some strains might be more invasive than others."

The other part of the equation that requires more understanding, Bogoch said, is why some people are hit with an invasive infection, while others who might have been exposed to the same strep A bacteria aren't.   

'The medical community does not have all the answers,' says Dr. Isaac Bogoch, an infectious disease specialist at University Health Network in Toronto. He says understanding invasive Group A strep bacteria is 'a major area of ongoing research.' (Craig Chivers/CBC)

"Some people might have subtle deficits to their immune system, or major deficits to their immune system, that might make them more predisposed to having an invasive infection," he said.

"So basically it's a dance between the bacteria itself and the person that the bacteria is on that might make someone more susceptible to having an invasive infection."

But as a physician who sees the devastating effects of invasive Group A strep infections like flesh-eating disease, the lack of concrete answers makes for "very challenging conversations" with patients and their families. 

"It is quite sad because sometimes we don't have obvious arrows pointing into a direction as to how this person acquired the infection," Bogoch said. 

Labs take swabs from patients and grow Group A streptococcus in petri dishes to help with diagnosis and to study the invasive form of the bacteria. (Craig Chivers/CBC)

But other times, those arrows point to risk factors that experts do know about. As with many communicable diseases, the most vulnerable people in society tend to be particularly susceptible to invasive strep A infections.

Those risk factors include homelessness — whether living on the street or living in crowded shelters. Another risk factor is injection drug use. 

The city of London, Ont., which struggles with both risk factors, has been battling an invasive Group A strep outbreak for two years.

Half of the more than 130 people infected in the city of 400,000 aren't properly housed, are battling drug addiction, or both, according to the Middlesex-London Health Unit. 

One of them is a woman who has been chronically homeless for months, sometimes sleeping in the streets and sometimes couch surfing. She suffers from addiction and uses injection drugs. CBC News has agreed to protect her identity because of the stigma she faces. 

Dr. Andrea Sereda, a family physician with London InterCommunity Health Centre, says providing adequate housing and better addiction treatment would help prevent many cases of invasive Group A strep infections among populations known to be at risk. (Craig Chivers/CBC)

Last spring, she had a bruise on her shin that turned into a blister, but didn't think anything of it until she became ill while with friends and they called an ambulance.

She remembers waking up in the hospital and staff telling her they were prepping her for surgery. 

"I said, 'For surgery for what?' And they said I have a flesh-eating bacteria on my leg," she said. 

Her surgeons removed a large chunk of flesh from her foot and shin. It took weeks before she could walk.

'It looks like a shark bit me'

"It looks like a shark bit me, bit half my foot off, leg off," she told CBC News. 

Unlike many people who are homeless, she was able to get housing after being discharged from hospital and has been able to keep her wound clean and bandaged, as well as complete her antibiotic treatment.

That's due largely to Dr. Andrea Sereda, who works with vulnerable women through the London InterCommunity Health Centre. 

Sereda said between the unhygienic living conditions caused by a lack of stable housing and her injection drug use, her patient was at high risk of invasive strep A infection, even through minor scrapes, bumps or wounds.

"Her infection was caught in time. She received great hospital care ... she was able to get housing at the right time," Sereda said. "All of those things meant that she's been able to recover.  But each step along the way, things could have fallen apart.

"She could have lost her leg."

For vulnerable patients with known risk factors, invasive Group A strep can be largely prevented by providing appropriate housing, effective addiction treatment, and safe consumption sites for injection drug use, Sereda said. 

But for many other Canadians without any apparent risk factors, like Cari Kirkness, the devastating infection comes, seemingly, out of nowhere.   

Dr. Liane Macdonald, a physician with Public Health Ontario, says collecting and analyzing information from patients infected by invasive Group A strep helps to increase overall understanding of the bacteria. (Craig Chivers/CBC)

"Sometimes we don't have a risk factor that we can identify.  So what we continue to do is, with each and every case, try to understand a little bit more about them, a little bit more about how that could add to our overall understanding in the broader population," said Dr. Liane Macdonald, a physician with Public Health Ontario.   

"I think we're still trying to understand this increase that we've been seeing."

How to protect yourself 

Although health experts are still trying to determine why the strep A bacteria turns invasive and why infections are on the rise, they emphasize these cases are still rare. They also recommend you:

  • Wash your hands frequently.
  • See a health care provider immediately if you have a throat infection that doesn't go away.
  • Seek immediate medical attention If you have a cut and your skin turns red or is hot or painful.
  • Ensure any drug paraphernalia you use, including needles, is safe and clean.


Nicole Ireland is a CBC News journalist with a special interest in health and social justice stories. Based in Toronto, she has lived and worked in Thunder Bay, Ont.; Iqaluit, Nunavut; and Beirut, Lebanon.

With files from Kennedy Schmidt