After a number of alarming reports of people losing limbs to invasive group A streptococcal disease, many Canadians are curious about the signs, symptoms and prevalence of this potentially deadly illness, which sometimes manifests itself as “flesh-eating disease.”

What is invasive Strep A?

According to the Public Health Agency of Canada, streptococcus A is a common bacterium usually transmitted through direct contact with or inhalation of discharges or droplets from an infected person's nose or mouth.

The vast majority of Strep A infections present as non-life-threatening conditions, such as strep throat or impetigo, a skin condition.

In rare cases, the bacteria can get into parts of the body that it doesn’t normally, such as the bloodstream. These “invasive” Strep A infections can be life-threatening.

Types of invasive Strep A conditions include septicemia (blood-poisoning), meningitis (inflammation of the membranes covering the brain and spine) and necrotizing faciitis, sometimes called “flesh-eating disease.”

How common is invasive Strep A in Canada?

There were 1,827 reported cases of invasive Strep A in 2014, according to the Public Health Agency of Canada. That translates to 5.14 cases per 100,000 people.

The 2014 incidence rate was about twice as high as a decade earlier when there were 2.68 reported cases per 100,000 people in 2004. It is not clear whether incidences of invasive infections are rising or whether they are simply being reported more. Reporting became mandatory in 2000.

Provincial health agencies report data on a monthly basis, so there are some more recent statistics available. In Ontario, for example, there were 91 cases of invasive Strep A reported in January 2017. That was up from 77 cases reported in January 2016.

How common is necrotizing fasciitis?

Most cases of invasive Strep A do not present as necrotizing fasciitis. According to Manitoba Public Health, there are 90 to 200 cases of necrotizing fasciitis per year in Canada, of which about 20 to 30 per cent are fatal.

What are the symptoms of necrotizing fasciitis?

According to HealthLinkBC, necrotizing fasciitis symptoms may include:

  • pain much worse than expected considering the size of an injury
  • pain that gets better over 24 to 36 hours, then suddenly gets worse
  • skin that is red, swollen and hot to the touch
  • a fever and chills
  • nausea, vomiting and diarrhea