Nine people have died and 132 cases of invasive group A streptococcus infections have been reported since an outbreak was first declared in Ontario more than 18 months ago.

Health officials in London, Ont. say the infections have led to Streptococcal Toxic Shock Syndrome in 15 per cent of the cases and necrotizing fasciitis, also known as “flesh-eating disease,” in another 15 per cent of them.

Although nearly half of the cases have been among intravenous drug users or those without stable housing, officials with the Middlesex-London Health Unit have noticed an increase in infections among patients not connected to that group, which prompted them to issue a public alert on Monday.

As doctors advise extra precaution, many are wondering how this happened and what’s causing the infections. For more information, breaks down what invasive group A streptococcus is and how to prevent it.

What is group A streptococcus?

Group A streptococcus (GAS) are common bacteria that can cause throat and skin infections, such as strep throat and cellulitis, the Middlesex-London Health Unit explained on its website.

The majority of GAS infections result in mild illnesses, such as strep throat. However, there are many different types of group A strep that can infect people and some are more invasive than others, Dr. Isaac Bogoch, an infectious disease specialist at Toronto General Hospital told CTV News Channel.

“The problem is, some strains are what we say more virulent, which means they’re more prone to causing disease,” he said on Tuesday. “People can get quite sick, quite fast and they need medical care.”

In the London, Ont. area, the bacteria have caused two severe illnesses: Streptococcal Toxic Shock Syndrome (STSS) and necrotizing fasciitis or “flesh-eating disease.”

Streptococcal Toxic Shock Syndrome occurs when the bacteria produces a toxin that spreads and can lead to toxemia in the blood and the “interaction on many different organ types and organ failures,” CTV News Medical Contributor Dr. Marla Shapiro told CTV News Channel on Tuesday.

Necrotizing fasciitis is an infection of the muscles or lining of the muscles, the Middlesex-London Health Unit said. Dr. Shapiro said necrotizing fasciitis can develop when bacteria travels from a wound to a muscle and infects the muscle, which puts the affected limb at risk.

“These are serious illnesses and we want the public to be aware but not to be overly alarmed,” Dr. Shapiro said.

How is it spread?

Dr. Marla Shapiro stressed that iGAS isn’t spread through the air, such as when someone coughs or sneezes. Instead, it’s typically transmitted through direct contact with secretions from the nose, mouth or throat or touching an open wound of an infected person, Dr. Bogoch said.

Strep infections normally increase during the colder, winter months, which is part of the reason why health officials are alerting the public to the potential risks at this time, Dr. Shapiro said.

Can it be prevented?

  • Wash hands regularly, especially after coughing or sneezing and before and after handling food.
  • Cover the mouth or nose with a tissue or sleeve instead of hands when sneezing or coughing.
  • Avoid sharing drinks, water bottles or eating utensils.
  • Drugs users shouldn’t share drugs, needles, filters or other paraphernalia.
  • Keep all wounds clean and watch for signs of possible infection, such as increased redness, swelling, drainage, and pain.
  • See a doctor if you have been in close contact with someone infected with invasive group A streptococcus.

Who is at the greatest risk?

According to the Middlesex-London Health Unit, anyone over the age of 65 and young children have the greatest risk of developing iGAS. Additionally, people with weakened immune systems or chronic diseases are also more susceptible.

Users that inject drugs and those who abuse alcohol also have increased chances of developing an infection. Lastly, people with chronic skin breaks or lesions, including children with chickenpox, are also at risk.

How is it treated?

Doctors will typically prescribe oral antibiotics if they suspect a GAS infection, health officials said. For iGAS cases, patients are usually treated with high-dose IV antibiotics in hospital.

Dr. Bogoch said it’s not difficult to diagnose or treat infections, but stressed that people who have been in close contact with an infected individual should also be treated with antibiotics as a preventative measure.