Invasive Group A Streptococcus (iGAS)
- Group A Streptococci (GAS) are common bacteria that live on the body and do not cause illness most of the time.
- The most common illness caused by GAS are sore throats and skin infections.
- Rarely, GAS can cause severe or life-threatening illness if it breaches the body’s barriers and enters certain tissues or organs. This is called invasive group A streptococcal disease or ‘iGAS’ for short.
- The symptoms and severity of iGAS can vary depending on which part of the body it invades, if a person has a weakened immune system and if treatment was started early.
- The bacteria can be spread from person to person by direct contact with skin or through the air by coughing and sneezing.
- There is no vaccination available to prevent GAS. The best way to protect yourself and others is to prevent infection through regular hand washing, staying at home and avoiding contact with others if you are unwell, and covering wounds.
- As of 1 July 2022, iGAS is a notifiable condition under the Public Health Act 1997.
Group A Streptococcus (GAS) and invasive Group A Streptococcus (iGAS)?
Group A Streptococcus is a bacterium that can live in the throat and on the skin of a person. GAS generally causes either no illness or mild disease, such as a sore throat (“strep throat”) or a skin infection such as impetigo and cellulitis.
Rarely, GAS can cause severe or even life-threatening illness if it enters parts of the body where it is not normally found, such as the blood (sepsis), muscles, nervous system (meningitis) or lungs (pneumonia). This is termed invasive group A streptococcal (iGAS) disease.
iGAS can happen if the person has breaks in the skin such as cuts or sores that allow the bacteria to enter, or if their ability to fight the infection is decreased due to chronic illness or an illness that weakens the immune system.
Other severe manifestations of iGAS are necrotising fasciitis and Group A Streptococcal Toxic Shock Syndrome (STSS).
What are the symptoms?
Symptoms usually start one to three days after exposure to the bacteria, however can be up to as long as 30 days and onset may be rapid. Infection symptoms vary depending on the site of infection but may include:
- Localised muscle tenderness
- High fevers and sweats
- Severe muscle aches
- Redness at the site of a wound
- Severe headache
- Shortness of breath or cough; or
- Dizziness and feeling faint
- Headache and/or stiff neck
- Nausea and vomiting.
How is it spread?
People with iGAS are infectious from seven days before becoming unwell until 24 hours after appropriate antibiotics are commenced.
The spread of GAS bacteria is more likely to happen among people with close, regular and prolonged contact. Rarely it may be transmitted through contact with objects.
Person-to-person spread may occur through:
- Direct skin contact, especially discharge from skin sores or wounds.
- Contact with respiratory secretions from the nose or mouth of an infected person, such as through intimate kissing.
- The air from coughing and sneezing.
Some people may be ‘colonised’ with the bacteria meaning they carry it in the throat or on skin without any symptoms but can spread the bacteria unknowingly.
Who is at risk?
People at risk of iGAS include:
- Anyone who has had close, prolonged, or intimate contact with a person with iGAS in the past 30 days.
- People with multiple medical problems or a weakened immune system.
- The elderly and the very young.
- Aboriginal and Torres Strait Islander people.
How is it diagnosed?
Clinical history, examination, and a link to a suspected or confirmed case may lead a doctor to suspect iGAS. The diagnosis can be confirmed in a laboratory through testing of blood or other body samples.
How is it treated?
Most people with iGAS will require hospitalisation. Treatment includes antibiotics along with other supportive measures such as pain relief and fluids.
People who develop necrotising fasciitis may require surgery to remove damaged tissue.
A person should isolate until they have completed 24 hours of antibiotics to prevent spread of the bacteria to others.
How is it prevented?
Several measures can be taken to reduce the risk or prevent infection with iGAS:
- Wash hands with soap and water or use an alcohol-based sanitiser, especially after coughing and sneezing and before preparing, eating or serving foods.
- Avoid close contact with people who are suspected or confirmed to have iGAS until they have been on appropriate antibiotics for 24 hours. If close contact is necessary during this period adopt droplet and contact precautions (such as goggles, mask, gown and gloves).
- People with “strep throat” should stay at home for at least 24 hours after starting antibiotics.
- Wounds should be kept clean and covered and monitored for signs of infection
- If you are unwell, stay at home and promptly seek medical assistance if iGAS symptoms appear.
There is currently no vaccination available for Strep A infection.
What should I do if I develop symptoms?
If you have been identified as a contact of someone with iGAS and you develop symptoms, you should immediately seek medical care and state you have been exposed to iGAS and are unwell. Wear a mask when outside your home or in your home if you can’t isolate from others in your home. Avoid close contact with others.
What should I do if I have contact with someone who has iGAS?
It is rare for people to develop the illness after being in close contact with someone who has iGAS, but you should monitor yourself for symptoms for 30 days.
Antibiotics are sometimes recommended in specific circumstances to people who are at increased risk of disease, in consultation with the Communicable Disease Prevention Unit.
Where to get help
- In an emergency call ‘000’ (triple zero) for an ambulance.
- You can also present to the emergency department of your nearest hospital or speak to your General Practitioner. Wear a face mask if you have respiratory symptoms.
- For other queries, contact the Communicable Diseases Prevention Unit (CDPU) on 1800 671 738 and ask to speak to a Clinical Nurse Consultant.