Global Courant 2023-04-20 16:00:00
Countries around the world are reporting a continued spike in invasive Group A streptococcal (iGAS) infections at a time when the strep infection season should be winding down, and Canada is one of them.
iGAS is one potentially life-threatening infection involving the normally harmless Group A Streptococcus bacteria (GAS). While a GAS infection often causes mild illnesses such as tonsillitis, strep throat, scarlet fever, and a skin infection called cellulitis, iGAS can cause serious illness and in rare cases death within days.
Ontario and Quebec have reported higher iGAS infection rates during the fall and winter 2022-2023 streptococcal season compared to pre-pandemic levels, and in Quebec, the infections have led to the death of several children and seniors.
Ontario reported 538 cases between October 2022 and February 2023, and Dr. David Fisman, a physician-epidemiologist and professor of epidemiology at the University of Toronto, says some of those cases were particularly serious.
“This is an uncommon infection, but when it does happen, it can be devastating,” Fisman told CTVNews.ca in an email Wednesday. “Since the emergence of Omicron, we’ve seen a surge of iGAS in surveillance data, and many of us who work clinically have also seen strangely severe iGAS.”
According to the World Health Organisation, Countries such as France, Ireland, the Netherlands, Sweden, the United Kingdom and the United States have also reported long-lasting spikes in iGAS cases. In the UK, 355 people across all age groups have died from infections this season.
WHAT IS iGAS?
GAS is a common bacteria that can only survive on and in humans, explains John McCormick, a professor of microbiology and immunology at the University of Western Ontario.
“It’s the same bacteria that many children carry in their throats asymptomatically without showing any signs of illness.”
Some people who carry GAS experience no symptoms, while others become ill with symptoms such as sore throat, fever, headache, and abdominal pain, but recover on their own or with the help of an antibiotic. These types of symptoms occur when the bacteria is present in a part of the body that is not considered infertile, such as the throat or the surface of the skin. It is normal for these parts of the body to be exposed to bacteria.
“So once you find (bacteria) in a location that’s supposed to be sterile, they call it invasive. And this particular one, when that happens, can get very dangerous,” McCormick said.
“For example, if it gets into your blood, or if it gets into the soft tissue, or even into your muscles — that’s necrotizing fasciitis or necrotizing myositis — that’s very rare, but it does happen and it can be very dangerous.”
Necrotizing fasciitis is also known as flesh-eating bacteria.
According to dr. Anna Banerji, a specialist in childhood infectious diseases, tropical diseases and global health at the University of Toronto, a patient who survives iGAS may also face long-term health problems.
“There may be post-strep complications that can affect the kidney and heart,” Banerji said.
WHY ARE THE FIGURES RISING?
According to Banerji, it’s probably no coincidence that iGAS infections peaked — along with respiratory viruses like RSV — after many countries lifted public health restrictions on COVID-19.
“Last year has been a really bad breathing season, so strep A can be carried in the throat and not have many symptoms, but when you have a cold, the strep can come in,” she said.
Like RSV, Banerji explained, many children avoided exposure to strep during the height of the pandemic and now wouldn’t have the antibodies needed to fight off an infection.
McCormick said there’s another popular theory with a handful of mutant strep A strains, including one named M1UK. M1UK was first discovered in the UK in 2019 and has been associated with spikes in scarlet fever and iGAS.
“It has a mutation in it, which means it makes a lot of venom… and that venom, as we know, could be involved in streptococcal toxic shock syndrome, which is a very dangerous form of the invasive disease.”
McCormick doesn’t know if M1UK or another GAS mutated strain has been linked to any of the iGAS cases reported in Canada this year, but he knows some strains made their way here. He has samples in his lab.
“We know they’re in Canada and the United States and other parts of Europe, so that’s probably contributing to the increase,” he said.
WHAT DOES THIS MEAN FOR CANADIANS?
The number of iGAS infections in Canada has been creeping up since 2000, but infections remain uncommon, generally affecting fewer than 10 people per 100,000.
“I don’t think people should be super worried, but I do think they should be aware of some of the symptoms,” McCormick said.
Because GAD is so common and many carriers are asymptomatic, McCormick said it’s hard to avoid exposure. Aside from common public health best practices like good hand hygiene, covering coughs and sneezes, and staying home if you’re sick, Canadians should know to intervene early when signs of a strep infection appear.
“If they have a child with a severe sore throat or fever and maybe a rash, they should see their GP and they’ll probably be prescribed an antibiotic,” he said.
