Health advisory:
Date Issued:
01 Nov 2017
Issued by:
Dr Brett Sutton, Acting Chief Health Officer, Victoria
Issued to:
Health professionals and laboratories

Key messages

  • There has been a recent increase in cases of invasive group A streptococcal disease (iGAS) in Victoria.
  • Clinical manifestations of iGAS include sepsis, streptococcal toxic shock syndrome, necrotising fasciitis, pneumonia/empyema, retropharyngeal abscess, osteomyelitis/septic arthritis, and (rarely) meningitis.
  • Young children, pregnant women and the elderly are at increased risk of iGAS infections.
  • There is an increased risk of secondary cases of iGAS in household contacts of index cases.
  • Household contacts require information about the increased risk and chemoprophylaxis should be considered.

What is the issue?

There has been an increase in the number of children admitted to the Royal Children’s Hospital (RCH) in Victoria with iGAS. Eleven iGAS cases were admitted to RCH from July to August 2017, similar to the number admitted for the entire year in 2016 (12 cases) and in 2015 (11 cases).  iGAS infection occurs when the group A streptococcus bacteria establishes infection in a normally sterile site such as the bloodstream. iGAS is more common in Australia than meningococcal disease and can be very severe, sometimes leading to streptococcal toxic shock. 

Who is at risk?

iGAS can affect anyone, however certain groups are at an increased risk. Older adults (>65 years of age) and infants (<1 year of age) have this highest incidence rates of iGAS. Pregnant and postpartum women are also at increased risk with a 20-fold increase in attack rate for iGAS. 

Household contacts, those people who have spent more than 24 hours in the same house as an index case in the seven days prior to symptom onset, are also at increased risk of iGAS. Secondary cases usually occur within a month of the index case, and predominantly in the first seven days. 

Symptoms and transmission

Group A streptococcus (caused by the bacteria Streptococcus Pyogenes) commonly colonises the skin, nasopharynx or anogenital tract and can cause a wide range of clinical disease, from mild illnesses such as pharyngitis and impetigo, to severe, life-threatening invasive infections (referred to as iGAS). 

Symptoms of iGAS include high fevers, severe muscle aches, sore throat, cellulitis, diarrhoea or vomiting, or severe headache. 

A clinical diagnosis can be confirmed by isolating group A streptococcus by culture from a normally sterile site, such as blood, cerebrospinal fluid, or pleural fluid.


Clinical information

iGAS is not notifiable in Victoria. Where necessary, expert advice should be sought from clinical infectious diseases specialists. If iGAS is suspected, specimens should be collected for culture, including blood cultures. 

Some experts and guidelines recommend antibiotic chemoprophylaxis to reduce the risk of iGAS in household contacts. Regardless of whether chemoprophylaxis is prescribed, all household contacts should be educated about their increased risk of iGAS and the early signs and symptoms of iGAS that require prompt medical evaluation. 

Recommendations regarding management of household contacts in cases of iGAS are available on the Royal Children’s Hospital Clinical Practice Guidelines website

Consumer information

Better Health Channel: Streptococcal infection – group A fact sheet