Spike in severe illness caused by strep A bacteria is 'global phenomenon' — including in Canada
Bacterial infection often leads to milder illness, but in rare cases can cause severe disease, rapid death
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.
Surges in multiple countries
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."
The U.K. was among the first countries to warn of a rise in invasive strep A infections this season and has since reported more than 2,651 cases across all age groups, compared to the final tally of roughly 2,900 across the whole of the "last comparably high season" in 2017 and 2018.
This season has hit 355 deaths, already one more than the final 2017 to 2018 count.
Researchers also recently reported on 2022 surges in iGAS in France and Denmark, while the U.S. Centers for Disease Control and Prevention (CDC) said cases this year have "remained high in children in some areas of the country even after respiratory viruses decreased in those areas."
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Antibiotic shortage
The CDC noted an added wrinkle: An ongoing shortage of liquid amoxicillin, which is often prescribed to children to treat early, milder group A strep infections.
That common antibiotic has also been on Health Canada's tier three shortage list since mid-November, which refers to shortages "that have the greatest potential impact on Canada's drug supply and health-care system."
A spokesperson for Health Canada told CBC News that there are signals the supply is improving, though overall demand remains higher than normal, which could impact supply at some pharmacies.
The department is working with the provinces and territories, manufacturers, and stakeholders across the supply chain and health-care system to "conserve existing supply, closely monitor planned resupplies to ensure that all available supply is released and distributed without delay to pharmacies and hospitals, and access foreign-authorized supply or alternatives, where possible," according to an emailed statement.
For iGAS infections, however, which require extensive medical treatment, amoxicillin isn't actually part of the arsenal, said Hota, but rather a slate of other antibiotics that are typically given intravenously.
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Certain symptoms should 'ring an alarm'
Those severe strep infections, several medical experts stressed, do remain quite rare. The bacteria spreads easily through respiratory droplets, but most people experience milder illness, while others aren't even aware they're infected.
"It's a very common bacteria, actually," said microbiologist Dr. Cécile Tremblay, a professor in the Department of Microbiology and Immunology at the Université de Montréal. "Many people in the population carry it, and often it does us no harm."
And while anyone can get hit by iGAS, the worst infections usually strike the most vulnerable — those individuals who are already battling another virus, or suffering from multiple comorbidities, or experiencing an open wound.
Dr. Donald Vinh, an infectious diseases specialist with McGill University, said fever, headaches, confusion and a decreased level of consciousness during a strep infection all signal a shift to more serious disease.
"Those constellations of symptoms usually should ring an alarm bell," he said.
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With files from Radio-Canada, CBC Montreal
