Invasive Group A Streptococcal (iGAS) Disease

What is Group A Streptococcus?

Group A Streptococcus (GAS) is a bacterium that can be found in the nose, throat, and on the skin of healthy people. When people have GAS but do not have any symptoms, they are referred to as carriers. GAS can cause a mild illness with symptoms such as a sore throat (commonly known as “strep throat”), impetigo or other skin infections, and less commonly scarlet fever, 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, direct contact with secretions from infected wounds or sores on the skin, or droplet spread (such as when an infected individual coughs or sneezes). The contagious period of GAS infection in untreated, uncomplicated cases is 10 to 21 days but can be weeks or months in untreated conditions with purulent (pus filled) discharge.  With adequate treatment, the contagious period generally ends within 24 hours.

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, fluid surrounding the lungs, or in the linings of the muscles or joints. It is also considered invasive if it causes the following severe infections:

  • Necrotizing fasciitis, also known as “flesh-eating disease” (destruction of skin and fat tissue)
  • Myositis (destruction of muscle tissue)
  • Meningitis (inflammation of the membranes covering the brain)
  • 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?
  • Early symptoms of necrotizing fasciitis and myositis include fever, severe localized pain, and in some cases, redness and swelling. Redness may spread quickly, up to 3 cm (1 inch) per hour
  • Early symptoms of meningitis include headache, stiff neck, sensitivity to bright lights, vomiting, and confusion
  • Early symptoms of streptococcal toxic shock syndrome include rapid onset of generalized or localized severe pain, dizziness, influenza-like symptoms, confusion, and sometimes, rash
Who is at the greatest risk of developing iGAS?

People who are at highest risk of developing iGAS include:

  • Very young children, especially those less than one year of age
  • Pregnant women and women who have recently given birth (postpartum)
  • People who are over the age of 60 years
  • People who have weakened immune systems, such as those who are on steroid treatment or chemotherapy, or with HIV infection
  • People with chronic diseases, like diabetes, heart or lung disease, or cancer
  • People who use injection drugs
  • People who abuse alcohol
  • People with chronic skin breaks and lesions, including children with chickenpox
  • People who have recently had surgery

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?

All confirmed GAS infections are 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

Varicella (chicken pox) vaccination for those eligible can help reduce the risk of iGAS, as the risk of iGAS infection is higher in persons with recent varicella infection

What is Ottawa Public Health's role?

All cases of iGAS must be reported to public health for follow up. The Infectious Disease Program receives a case report, identifies and notifies close contacts, and assesses the need for preventive treatment with antibiotics. Ottawa Public Health also collects data about occurrences and epidemiological trends about this infection.

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