Understanding a rare illness: invasive group A streptococcal disease

Ciara Baker is a microbiologist with the Group A Streptococcal Research Group, led by Associate Professor Andrew Steer, at the Murdoch Children's Research Institute. The group’s surveillance of IGAS is supported by funding from the Shepherd Foundation. 

Invasive group A streptococcal disease (IGAS) is a rare, yet life-threatening disease that most people aren't aware of. We are doing our part to make sure all children can one day be protected against it.

In 2014 the Group A Streptococcal Research Group at the Murdoch Children’s Research Institute started a pilot surveillance study of IGAS. We wanted to find out:

  • How common the disease was in Australia
  • What sort of symptoms children tend to display, and
  • Gather data to support the creation of a group A streptococcus vaccine.

The group A streptococcus (GAS) is a common bacteria found on our bodies. 15% of the population carries it at any time without causing any problems. It is found mainly in the throat and nose but can be found on the skin as well.

While the most common forms of GAS disease are sore throat and skin infection, the rare invasive form of the disease occurs when bacteria enter sterile parts of the body like the blood, cerebrospinal fluid, or in the thin fluid around the lungs that helps us breathe.

Children can end up in the intensive care unit suffering from streptococcal toxic shock syndrome (STSS) and multisystem organ failure. Children who survive may be left with long term risks of secondary diseases.

The disease becomes life threatening very quickly, so the best solution is prevention. That’s why a vaccine is so important. At the moment there are three or four vaccines in development. These vaccines must aim at specific “emm proteins” within the bacteria, which means they will only be effective against certain GAS strains.

After a child is diagnosed with IGAS we carry out genetic typing of the sample to confirm which "emm type" the bacteria contains. There are over 220 different strains of GAS containing many different types of the "emm protein", which is why ongoing surveillance of the disease is so important.  It is crucial that we know what strains are out there in the community to make sure that the vaccines cover the most common and most dangerous types.

This year the study is being rolled out in hospitals across most of Australia via the PAEDS network.  This will give us a much clearer picture of the different variants of the disease out in the community.

I love microbiology because infectious diseases are so interesting, and for the most part they are all treatable and preventable. What I love about my job specifically is being able to go and recruit families for our study. I love to go and meet the families and the kids. I’m so lucky that I get to experience both the lab side and the personal side.