Invasive Group A Streptococcal (iGAS) disease
Group A Streptococcus (GAS) is a bacterium often found in the throat and on the skin. The most common infections caused by GAS are sore throat (“strep throat”) and skin infections such as impetigo and cellulitis. Most people who come into contact with GAS remain well and symptom-free, or develop throat and skin infections. Other diseases may occur following GAS infections such as acute rheumatic fever (a disease affecting the heart and joints) and post-streptococcal glomerulonephritis (a disease affecting the kidneys).
Severe and sometimes life-threatening GAS disease may occur when the bacteria enter parts of the body where bacteria are not normally found, such as the blood, muscle or lungs. These infections are called invasive GAS (iGAS) disease. The people most at risk of iGAS infection include:
- household contacts of someone with iGAS in the past 30 days
- children younger than 5 years
- people older than 65 years
- pregnant and post partum women
- First Nations people
- people with weakened immune systems.
Signs and symptoms
A person with iGAS infection can become very ill within 12–24 hours. Early signs and symptoms of iGAS may include:
- high fever
- dizziness
- shortness of breath and/or chest pain
- headache and/or stiff neck
- severe muscle aches
- localised muscle tenderness
- sometimes redness at the site of a skin wound.
Symptoms of iGAS can depend on where the infection is in the body. Other serious manifestations of iGAS include sepsis and severe invasive infection.
If you develop any of these symptoms after having contact with a person diagnosed with iGAS, please seek medical advice immediately. Tell your doctor that you have been in contact with someone recently diagnosed with iGAS disease and that you have developed some symptoms that you are worried about.
Treatment
Prompt antibiotic therapy is required for iGAS disease. See a doctor as soon as you notice severe symptoms, or mild symptoms that are getting worse. Most people need admission to hospital for supportive treatment. People with necrotising fasciitis may require surgery to remove damaged tissue.
Transmission
Streptococci survive in throats and on hands for long enough to allow easy spread between people through coughing, sneezing, kissing or skin contact. People may sometimes carry the bacteria in their throat or skin without any symptoms of illness. They are known to be 'colonised' with the bacteria.
Invasive GAS (iGAS) infections can occur when the bacteria get past a person's defences. This may happen when a person has sores or breaks in the skin (such as cuts, insect bites, burns, or surgical procedures) that allow the bacteria to get into the tissue, or when the person's ability to fight infection is decreased because of chronic illness or an illness that affects the immune system.
Healthy people can sometimes get iGAS infection from close contacts such as a family member, but this is rare.
Prevention
Practice of good hygiene is the most effective way to prevent spread and infection with GAS. To reduce the spread of bacteria it is important to wash hands, especially after coughing and sneezing and before preparing, eating or serving foods. Wash, treat, and cover skin sores and wounds until healed. Children with impetigo or school sores should not attend school or other group settings until the blisters have dried out. Where a doctor has recommended starting a course of antibiotics, people should stay at home until 24 hours after starting them. In special situations (e.g. if spread of iGAS has been identified) people who are identified as carrying the bacteria may be required to stay at home for longer.
Ensure that anything used as dressings or to cover wounds (tapes, bandages, or band aids) must be discarded in the rubbish. Bacteria can spread on linen, towels, clothes and wash cloths, so it is important that these are washed using a normal laundry detergent and cycle before they are next used.
Contact with someone with iGAS
If you live or have spent a lot of time with someone who has had iGAS within the last 30 days, you need to watch for signs of iGAS infection.
If you develop any skin infections, a sore throat or other symptoms of iGAS, you should see your doctor as soon as possible. Make sure to tell your doctor about your close contact with someone with iGAS.
Health outcome
The course of disease depends on where the infection is in the body, the person's immune system, and access to prompt and appropriate treatment.
Two of the most severe forms of iGAS are:
- necrotising fasciitis (a severe infection involving areas of soft tissue below the skin), and
- streptococcal toxic shock syndrome (a rapidly worsening illness where blood pressure is very low and organs within the body may fail).
These severe iGAS infections have a higher chance of complications and some people with iGAS infection may not survive. People who survive iGAS infection can sometimes develop long-term disability.
Other resources
13Health (call 13 43 25 84)
References
- Department of Health. Victoria [Internet]. State Government of Victoria, Australia; [cited 2024 Jan 30]. Update on invasive group A streptococcal disease. Available from: https://www.health.vic.gov.au/health-advisories/update-on-invasive-group-a-streptococcal-disease
- ACT Health. Invasive group A streptococcal disease (iGAS) [Internet]. Available from: https://www.health.act.gov.au/sites/default/files/2023-05/Invasive%20group%20A%20streptococcal%20disease_Factsheet.pdf
- Healthdirect Australia [Internet]. Healthdirect Australia; 2023 [cited 2024 Jan 30]. Group A Streptococcal disease. Available from: https://www.healthdirect.gov.au/group-a-streptococcal
- Australian Government Department of Health and Aged Care [Internet]. Australian Government Department of Health and Aged Care; 2024 [cited 2024 Jan 30]. Invasive Group A Streptococcal (iGAS) Disease – CDNA National guidelines for Public Health Units. Available from: https://www.health.gov.au/resources/publications/invasive-group-a-streptococcal-igas-disease-cdna-national-guidelines-for-public-health-units?language=en
- Telethon Kids Institute [Internet]. [cited 2024 Jan 30]. Invasive Streptococcus A Disease. Available from: https://www.telethonkids.org.au/our-research/research-topics/invasive-strep-a-disease/