Invasive Group A Streptococcal (iGAS) Disease

What is Group A Streptococcus?

Group A Streptococcus (Group A strep, or GAS) is a bacteria found in the nose, throat, and on the skin of healthy people. GAS can cause a mild illness with symptoms such as a sore throat (commonly known as “strep throat”), scarlet fever, and impetigo or other skin infections, or a more serious illness due to invasive infections.

How does GAS spread?

GAS bacteria are spread by direct contact with secretions from the nose and throat of an infected person, or by direct contact with secretions from infected wounds or sores on the skin.

What is invasive GAS (iGAS)?
GAS infection is considered invasive when it is found in places in the body that are normally sterile, such as blood, the fluid surrounding the brain, or in the linings of the muscles or joints. Severe infections are rare, but can result in necrotizing fasciitis or streptococcal toxic shock syndrome (STSS), a life-threatening condition that causes low blood pressure and failure of multiple organs.
What are early symptoms of iGAS?
  • A person with this serious form of GAS infection can become very ill within 12 – 24 hours.
  • There can be a history of flu-like symptoms such as fever, pain and muscle ache before signs of infection or rash quickly develop.
  • In other cases there may be severe pain, swelling, redness or swollen lymph nodes associated with a recent cut or injury.
It is important that children with chicken pox are watched for symptoms of iGAS. If the fever lasts more than 3 days or recurs, or if redness, swelling, and severe pain develop around a chicken pox lesion, they should be seen by a health care provider without delay.
What is the treatment for GAS infections?

GAS infections can be treated with antibiotics (Note: most sore throats are caused by viruses, not GAS, and do not require antibiotics). In cases of iGAS, early medical treatment is critical to reduce the risk of complications and death.

How can GAS infections be prevented?

To prevent the spread of GAS infection, it is recommended that you:

  • Wash your hands well, especially after coughing and sneezing, before preparing food, before eating, and before and after cleaning or handling a cut or wound.
  • Keep all wounds clean and observe for signs of infection, such as increased redness, swelling, drainage, or pain at the wound site; see your health care provider immediately if the wound looks infected, especially if a fever develops.
  • Stay at home for at least 24 hours after the start of antibiotic treatment for strep throat or impetigo.
What is Ottawa Public Health's role?

All cases of iGAS must be reported to public health for follow up. The Communicable Disease Program receives a case report, identifies and notifies close contacts, and assesses the need for preventive treatment with antibiotics.

For further information call Ottawa Public Health at 613-580-6744 or visit

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