Invasive group A streptococcus factsheet


Group A streptococcus (Strep A) is a type of bacteria that is found on the skin and in the throat.

It is usually responsible for common childhood conditions like:

Strep A can also cause complications that can damage the heart, like rheumatic fever, and kidneys, like glomerulonephritis. In rare cases can cause a serious, life-threatening infection called Invasive group A streptococcal disease (iGAS).

iGAS can happen when the strep A infection gets into parts of the body where bacteria is not normally present.

These include areas like the:

  • muscles
  • lungs
  • blood stream.

iGAS is a life-threatening disease and needs urgent admission to the hospital. It can cause other life-threatening infections like:

  • sepsis - the body not responding properly to infection
  • toxic shock syndrome - toxins from infection getting into the blood stream
  • necrotising fasciitis - infection that results in the death of the body’s soft tissue
  • meningitis - swelling of the membranes that cover the brain and spinal cord
  • pneumonia - an infection that causes the air sacs in the lungs to fill with fluid.

 Signs and symptoms

Symptoms of a strep A infection can look different depending on:

  • which part of the body has the infection
  • the type of illness caused by the infection
  • how severe the illness is.

General symptoms can include:

  • fever
  • muscle pains
  • sores
  • swelling and redness of the infected area.

Symptoms will be either:

  • in the throat, like in strep throat or tonsilitis
  • on the skin, like impetigo or cellulitis
  • both in the throat and on the skin, like in scarlet fever.

Symptoms of iGAS will show between 12 – 24 hours after the infection develops.

They include:

  • high fever, chills and/or sweats
  • shortness of breath
  • chest pain
  • severe muscle ache and tenderness
  • nausea and vomiting
  • redness around any wounds or sores.

Present to your nearest emergency department immediately if your child is showing signs of iGAS.


Your child’s doctor will diagnose strep A and iGAS based on the symptoms they show, and by doing tests including blood test and swab of the throat or skin sores.


Strep A and iGAS are treated with antibiotics. Your child will need to isolate until they have completed the first 24-hour period of antibiotics. You should then keep your child at home from daycare and school during the full course of antibiotics to reduce the spread of infection in the community.

For severe infections, your child will need to be admitted to hospital for treatment. Your doctor may also prescribe antibiotics for members of your household who have been exposed.


Preventing the spread of invasive group A streptococcus

Step A bacteria is very common. Approximately 1 in 3 people carry the bacteria on their body without any symptoms or illness.

The bacteria is spread from person to person by:

  • droplets in the air from coughing, sneezing and talking
  • contact with the bacteria on skin
  • contact with the bacteria on surfaces and objects, like toys or water bottles.

Teaching your child good hygiene habits is the best way to prevent the spread of strep A. Good hygiene habits can include:

  • coughing and sneezing into their hand, tissue, or sleeve
  • regular hand washing with soap
  • wearing a mask when unwell
  • not sharing things like water bottles and eating utensils.

You can also help your child by:

  • keeping any wounds clean and covered until they heal
  • seeing your local doctor as soon as possible if you or your child has a sore throat or skin sores
  • seeing your local doctor as soon as possible if you or child become unwell and have been in contact with a person with Strep A infection in the last 30 days
  • keeping your family up to date with immunisations for chicken pox and influenza.

Risk factors for invasive group A streptococcus

Children are most at risk of strep A infection as they are less aware of good hygiene habits, have more physical contact with others through play and tend to be in more crowded places like schools and daycare.

Other risk factors for children include:

  • being an infant under one year of age
  • being a newborn to a mother with iGAS
  • recent physical trauma, burns or surgery
  • recent infection with chickenpox or influenza
  • being immunocompromised, for example being on steroids or undergoing chemotherapy
  • being Aboriginal and/or Torres Strait Islander
  • being in a household with someone who has iGAS.
Last updated Monday 11th March 2024


This factsheet is provided for general information only. It does not constitute health advice and should not be used to diagnose or treat any health condition.

Please consult with your doctor or other health professional to make sure this information is right for you and/or your child.

The Sydney Children’s Hospitals Network does not accept responsibility for inaccuracies or omissions, the interpretation of the information, or for success or appropriateness of any treatment described in the factsheet.

© Sydney Children’s Hospitals Network 2024