Strep throat bug also causes flesh-eating disease, but why is a 'random game': Montreal doctor

Strep A infections up in Canada Recognize the signs of group A streptococcus bacteria before it's too late.

An infectious disease physician says that when someone is infected with group A streptococcus bacteria, it's "kind of a random game" what comes next.

Dr. Donald Vinh says it could turn into the type of illness known as strep throat.

But in rare cases, it could result in the rare flesh-eating disease necrotizing fasciitis that recently claimed the leg of a firefighter from Vancouver.

Vinh, with the McGill University Health Centre (MUHC), says necrotizing fasciitis is among the "scariest" infectious diseases he's ever seen, one of the "classic bugs" that every medical professional is taught to watch for because it can kill within hours.

The tissue-killing infection can spread quickly, he says, even if the patient receives antibiotics or surgical treatment to remove the dead tissue or limb.

"Despite optimal therapy, the mortality rate for this beast is alarmingly high," he said.

Vinh says people can carry the "strep A" bacteria on their skin or in their nose and throat without getting sick, or they may develop strep throat.

For others, the bacteria can lead to "invasive" infections, including necrotizing fasciitis and streptococcal toxic shock syndrome, he says.

Vinh says it's not clear why there is such wide variability.

"Somewhere along the way from exposure to, in a small proportion of people, severe disease, there's something that occurs that we don't understand," he said.

The person has to have picked up strep A somewhere, he adds.

"We don't know whether it gets on your skin or in your airways — before you get these severe diseases like necrotizing fasciitis," he notes. "But that's the big black box."

The infection can start in a minor cut or scrape or following a chickenpox infection, Vinh said.

Sometimes, there is no obvious wound or injury to the skin.

That was the case for Christopher Won, an assistant fire chief with Vancouver Fire Rescue Services who is recovering in a Hong Kong hospital after the infection forced the amputation of one of his legs above the knee on Feb. 15.

Won's partner, Marie Hui, says the family can't recall Won having any wounds or insect bites when he began feeling the symptoms during a family vacation.

Hui says Won is "lucky to be alive, and very grateful for another day," as the couple and their two children wait for him to be cleared to fly home to Vancouver.

Vinh says one of the earliest signs of necrotizing fasciitis is a limb that is painful to a degree that's disproportionately worse than any visual signs, such as redness.

In that way, the fast-moving infection can be "deceptively visually benign," he said.

Sometimes, in the absence of any alarming visual cues, people mistake the pain for a muscle strain and delay seeking medical attention until it's too late, he adds.

There's no vaccine against "group A strep," and infections caused by the bacteria are rising in Canada and around the world, Vinh said.

A course of penicillin is usually enough to knock down the more superficial skin or strep throat infections.

Vinh is encouraging anyone sick with strep throat to seek medical attention for antibiotics to treat the infection and decrease the risk of transmission.

-- This report by The Canadian Press was first published Feb. 27, 2024.