Information leaflet for patients with invasive group A streptococcal infection

What is group A Streptococcus? 
Group A Streptococcus (GAS) is often found in the throat and on the skin. People may carry it in their throat or on their skin and not be ill. Most GAS infections are fairly mild illnesses such as “strep throat” and impetigo (skin infection). It is very unusual for it to cause other severe infections.

How is it spread? 
GAS spreads between people through sneezing, kissing and skin contact. People who are already sick with GAS are most likely to spread the infection. Healthy people who carry the bacteria but have no symptoms are much less contagious.

What kinds of illnesses are caused by GAS and what is invasive GAS disease?
Some people can carry GAS in their throat and have no symptoms – this is called ‘colonisation’.

However GAS sometimes causes infections if it enters the body.

  • Most GAS infections are mild illnesses, such as sore throat and impetigo (skin infections).
  • It is very unusual for GAS to cause more severe illness but it can happen, these infections are called ‘invasive GAS disease’ which can be life-threatening. This can happen when GAS gets into parts of the body where it is usually not found, such as blood, muscle or the lungs. Two of the most severe, but least common forms are necrotising fasciitis and streptococcal toxic shock syndrome. Necrotising fasciitis destroys muscles, fat and skin tissue. Streptococcal toxic shock syndrome causes a rapid drop in blood pressure which causes organ failure (e.g. kidneys, liver, lungs).

Why does invasive GAS disease happen? 
Invasive GAS infections happen when the bacteria get past the defences of the person who is infected. This may happen when someone has sores or other breaks in the skin that allow the bacteria to get into the tissue, or when someone can’t fight off infection because of chronic illness or an illness that affects the immune system. Some strains of GAS are more likely to cause severe disease than others.

Who is most at risk of getting invasive GAS disease? 
Most people who come in contact with GAS will not develop invasive GAS disease. Most will have no symptoms at all, but some may have a throat or skin infection. Although healthy people can get invasive GAS disease, people with chronic illnesses like cancer, diabetes and kidney dialysis patients, and those who use medications such as steroids, are more at risk. 

How is GAS disease treated? 
GAS infections are treated with antibiotics. The earlier these can be taken the better. People with necrotising fasciitis, may need surgery to remove damaged tissue. 

Why will the public health doctor get in contact with my household/other close contacts?
Because GAS spreads between people through sneezing, kissing and skin contact, close (household) contacts are most at risk of getting GAS. Most people who come in contact with GAS remain well and symptom free, or may develop mild illness such as sore throat or skin infection. The public health doctor will give your close contacts an  about GAS.

How can GAS infection be prevented? 
Washing your hands - especially after coughing and sneezing - and before preparing foods or eating - reduces the spread of all types of GAS infection. People with "strep throats" should stay at home for 24 hours after taking an antibiotic. Anyone with signs of an infected wound, especially if fever occurs, should seek medical care.

Last reviewed: 28 June 2012