Department of Health

Health warning on invasive group A streptococcal disease

Health advisory

Advisory number:
Date issued:
22 Dec 2022
Issued by:
Professor Brett Sutton, Chief Health Officer
Issued to:
Health professionals

Key messages

  • A recent increase in cases of invasive group A streptococcal disease (iGAS) has been observed in Victoria, and internationally. 
  • iGAS is caused by infection with a bacterium known as Group A (beta-haemolytic) Streptococcus, which also commonly causes skin and throat infections.  
  • Clinical manifestations of iGAS include sepsis, streptococcal toxic shock syndrome, necrotizing fasciitis, pneumonia/empyema, retropharyngeal abscess, meningitis, osteomyelitis and septic arthritis.
  • Young children, pregnant or post-partum women, and the elderly are at increased risk of iGAS.
  • Clinicians should consider testing, urgent hospital referral and empiric treatment for patients with a compatible clinical illness.
  • The overall risk of iGAS for the general population remains low. 
  • iGAS is a routine notifiable condition in Victoria (laboratories only).

What is the issue?

Invasive group A streptococcal disease (iGAS) is caused by infection with a group A Streptococcus (GAS) bacterium (also known as Streptococcus pyogenes or Strep A). GAS can cause a spectrum of disease from non-invasive infections such as pharyngitis, impetigo and scarlet fever, to invasive disease (iGAS) including bacteraemia, necrotising fasciitis and streptococcal toxic shock syndrome. 

An increase in iGAS presentations, particularly among children, has been observed in Victoria over the last few months.

An increase in iGAS has also been reported in some European countries in the last few months. Some countries, including the United Kingdom, have also observed an increase in cases of scarlet fever. 

The Department of Health is closely monitoring the situation in Victoria. 

Who is at risk?

The overall risk of iGAS for the general population remains low. 

People most at risk of iGAS include:

  • household contacts of someone with iGAS in the past 30 days
  • people older than 65, or younger than 5 years
  • Aboriginal and/or Torres Strait Islander people
  • people who inject drugs
  • people who are immunocompromised (for example those on steroids or chemotherapy) or have a chronic disease (such as diabetes)
  • pregnant and post-partum women.

Bacteria may enter the body through damaged or broken skin, such as cuts, insect bites, burns, or surgical procedures, increasing the risk of iGAS.

Those who live in houses that are overcrowded or do not have hot water or working taps are also more at risk of infection as GAS bacteria are more likely to spread.

Symptoms and transmission

General symptoms

GAS bacteria generally cause mild disease such as pharyngitis (strep throat) and impetigo (skin sores); however, they can also cause iGAS. iGAS is a severe disease which can include sepsis, toxic shock syndrome, necrotising fasciitis, maternal sepsis, meningitis, bone/joint infections, and pneumonia.

Symptoms of iGAS vary depending on site of infection and are often non-specific. They may include:

  • fevers or chills
  • dizziness
  • shortness of breath and/or chest pain
  • headache and/or stiff neck
  • nausea and vomiting
  • red, warm, painful, and rapidly spreading skin infection which may have pus or ulceration
  • abdominal pain, bleeding, or purulent discharge from the vagina can occur with maternal sepsis.

Symptoms in children

Signs and symptoms of iGAS in children are non-specific but can include fever, erythematous sunburn-like rash (scarlet fever rash, which may be subtle or florid), cold or mottled limbs, limb pain, not wanting to walk, poor feeding, abdominal pain, vomiting, lethargy, throat infection, pneumonia and pleural effusion, and oliguria. iGAS may initially be difficult to distinguish from a viral infection, however the persistence of these signs, the presence of multiple signs, or their extreme nature, signals likely serious bacterial infection rather than a common viral syndrome. 


GAS bacteria are usually transmitted via large respiratory droplets or direct contact with infected people or carriers (people who carry the bacteria on their skin or in their throat and can spread it, but do not develop symptoms). 


  • Clinicians should be alert for the signs and symptoms of iGAS and should thoroughly evaluate all patients with a clinically compatible illness. 
  • Be alert to the patient, particularly an infant or child, who is more unwell than you would expect with a viral illness, or who had a viral illness and then became more unwell.  
  • Laboratory investigations should include blood cultures, full blood examination and venous blood gas.
  • Management of suspected iGAS should include early resuscitation, empiric antibiotics and urgent escalation. Management in a tertiary centre may be required.
  • Clinicians should seek advice from an infectious diseases physician on definitive management and follow up of cases of iGAS and their contacts. 
  • Laboratories must notify the Department of Health of all confirmed iGAS cases within 5 working days.

Reviewed 23 December 2022


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Communicable Disease Prevention and Control section

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