This document should be considered a ‘live document’ and will be reviewed and updated regularly in response to:
  • New legislation or statutory directions; OR
  • Changes in advice based on emerging evidence or national guidelines; OR
  • Learnings from outbreak management locally, in other jurisdictions and internationally

KEY POINT: There has been an increase in invasive group A streptococcus (iGAS) infections both internationally, in the Eastern States and recently in WA. Be alert for signs and symptoms of iGAS infections

Infectious Agent

Bacteria called  Streptococcus pyogenes also known as Group A Streptococcus (GAS). Group A streptococcus is often found in throat and skin. Can cause a range of diseases and includes:

  • Superficial infections such as pharyngitis, impetigo and pyoderma
  • Scarlet and puerperal fever
  • Severe invasive disease such as septicaemia, meningitis, necrotising fasciitis and toxic shock syndrome
  • Post-streptococcal immunological sequelae including acute rheumatic fever and acute glomerulonephritis
Mode of Transmission


  • Direct contact with nose or throat secretions or with infected skin lesions

Droplet/Airborne (respiratory):

  • Inhalation of respiratory droplets/aerosols
Incubation period

Not well defined. Usually 1-3 days, however can be up to 30 days

Infectious period

Cases are infectious from 7 days before symptom onset until symptoms have resolved or after 24 hours of effective antibiotic therapy has been initiated

Signs and Symptoms

IGAS presentations vary depending on site and severity of infection and can include:

  • Fever and/or chills
  • Shortness of breath and/or chest pain
  • Red, warm, painful and rapidly spreading skin infections which may have pus or ulcerations
  • Clinical picture of sepsis or shock, including multi-organ failure
  • Nausea, vomiting, abdominal pain
  • Dizziness, headache and/or neck stiffness
  • Puerperal sepsis may present as vaginal bleeding or purulent discharge. Evaluate mother and infant pairs

In children, signs and symptoms of iGAS infection can be non-specific but can include fever, rash (including scarlet fever rash), cold or mottled limbs, headache, abdominal or limb pain, poor feeding, reduced urine output, vomiting, lethargy, seizures, increased work of breathing, and persistent tachycardia.

iGAS may occur concurrently with, or following, a viral infection.

Clinical Considerations

Have a low threshold to transport to ED

Early recognition of sepsis is vital - refer to Sepsis CPG

NEWS2 calculator should be utilised for all cases presenting with signs and symptoms of  iGAS

Precautions required

Contact and Droplet/Airborne:


  • Gloves
  • P2/N95 respirator (Fit tested and checked)
  • Eye protection
  • Risk assess need for gown/coveralls
  • Patient to wear a surgical mask if able to tolerate

Vehicle airflow

Ensure vehicle airflow set per WIAMB22 Ambulance Airflow (Login required)

Cleaning required

See Vehicle Cleaning and Spills Management - after transporting a patient requiring transmission-based precautions (contact, droplet/airborne)

Waste management

Heavily soiled items should be disposed of as clinical waste

Linen management

Items should not be shaken or handled in a manner that may disperse any infectious particles into the environment

Shared transport

Patients who are symptomatic with suspected or confirmed iGAS must not share transport with other patients




WA Health Alert for Clinicians. Increase in invasive group A streptococcus (iGAS) infection notifications (17th January 2023)

Interim guidelines for the public health management of invasive group A streptococcal infections in Western Australia Version 1 https://www.health.wa.gov.au/~/media/Corp/Documents/Health-for/Infectious-disease/iGAS/WA-Interim-Public-Health-Guidelines-for-iGAS.pdf 


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Head of Clinical Services


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