Update on invasive group A streptococcal disease

Key messages

• Invasive group A streptococcal disease (iGAS) including cases of severe illness, particularly among children, continues to be observed in Victoria.
• iGAS is caused by infection with a bacterium known as Group A Streptococcus (GAS), which also commonly causes skin and throat infections. Clinical manifestations of iGAS include sepsis and severe invasive infection.
• Young children, pregnant or post-partum women, and the elderly are at increased risk of iGAS.
• Clinicians should be alert to the potential for iGAS among children presenting with sore throat and fever. Consider testing and empiric treatment for patients with signs of GAS infection and urgent hospital referral for those with clinical illness compatible with iGAS.
• Parents and guardians should be alert to the signs and symptoms of GAS infection and serious bacterial infection and know when to seek immediate medical care.
• Parents and guardians should ensure children are up to date with routine immunisations, to help prevent viral infections that increase the risk of iGAS.
• The overall risk of iGAS for the general population remains low.

What is the issue?

Invasive group A streptococcal disease (iGAS) is caused by infection with the group A Streptococcus (GAS) bacteria (also known as Streptococcus pyogenes). 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 since late 2022. Although notified cases have declined since January 2023, clinicians in Victoria continue to report seeing more cases of iGAS in children than is usual for this time of year, including more cases of severe disease.

Higher than expected levels of iGAS have been reported interstate and internationally since late 2022, including in the United Kingdom and the United States.

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 from the Pacific Islands
• people who inject drugs
• people experiencing homelessness
• people who are immunocompromised (for example those on steroids or chemotherapy) or have a chronic disease (such as diabetes)
• pregnant and post-partum women
• people living in overcrowded housing or with no access to clean water or effective sanitation.
• Increases in iGAS tend to be observed when there are increases in influenza and other respiratory viruses. Children with chickenpox are also at higher risk of developing iGAS. Immunisation can prevent some of these infections. There is no vaccine to protect against iGAS infection.

Symptoms and transmission

General symptoms

GAS bacteria generally cause mild non-invasive disease such as tonsillitis/pharyngitis (strep throat), cellulitis, impetigo (skin sores) and scarlet fever; 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 the 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

iGAS may initially be difficult to distinguish from a viral infection and the signs and symptoms can be non-specific. However, the presence and persistence of the following signs, signals likely serious bacterial infection rather than a common viral syndrome.

Signs and symptoms of iGAS in children can include fever, red sunburn-like 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, chest infection and oliguria (poor urine output).

Transmission

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). Bacteria may also enter the body through damaged or broken skin, such as cuts, insect bites, burns, or surgical procedures.

Recommendations

For health professionals

• Clinicians across all healthcare settings should be alert for the signs and symptoms of GAS and iGAS infection and should thoroughly evaluate all patients with a clinically compatible illness, including those presenting with sore throat and fever.
• Clinicians in primary care should consider the diagnosis of streptococcal pharyngitis in children presenting with sore throat. Collect throat swabs for GAS culture, prescribe empiric antibiotics if indicated and refer urgently to hospital those with a clinical illness compatible with iGAS.
• 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.
• Advise parents and guardians of children presenting with suspected viral illnesses to be alert to the signs and symptoms of serious bacterial infection and when to seek immediate medical care.
• Laboratory investigations for suspected iGAS 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.

For the public

• Parents and guardians are strongly encouraged to ensure children are up to date with all routine immunisations (including varicella (chickenpox) and upcoming annual influenza vaccination), to help prevent viral infections that increase the risk of iGAS.
• Parents and guardians should be alert to the signs and symptoms of GAS infection and serious bacterial infection in children, and when to seek immediate medical care.