Health Topics

Group A Streptococcus (GAS)

Group A Streptococcus (GAS) is a germ (bacteria) that is often found in the throat, nose and/or on the skin. People may carry the GAS bacteria and have no symptoms of illness. Most GAS infections are mild illnesses such as "strep throat," or impetigo, on rare occasions, these germs can cause severe and even life-threatening illnesses.

How is GAS Spread

  • GAS bacteria are spread through direct contact with mucus from the nose or throat of persons who are infected.
  • GAS can also be spread through contact with infected wounds or sores on the skin of infected persons.
  • Persons who are sick with GAS (i.e. strep throat, skin infection etc.) are most likely to spread the GAS to others. Those who carry the bacteria but have no symptoms are much less contagious.
  • It is not likely that household items (i.e.  toys, door knobs) spread GAS bacteria.
  • With proper antibiotic treatment, a person can stop being contagious within 24 hours.  However, it is important to complete the entire antibiotic treatment as ordered by your health care provider.

What kinds of illnesses are caused by GAS infection?

GAS Infection can cause different symptoms depending on what part of the body is infected. Some illnesses can be:

  • No illness (carry the bacteria but have no symptoms)
  • Mild illness (most common) such as sore throat (strep) or a skin infection (impetigo, pyoderma)
  • Serious illness such as scarlet fever, rheumatic fever, cellulitis or pneumonia
  • Severe illness (invasive GAS) such as disease of the blood (toxic shock syndrome), disease of the muscle or fat (necrotizing fasciitis) or disease of the fluid surrounding the brain and spinal cord (meningitis)

Who is most at risk of getting invasive GAS?

Very few people who come in contact with GAS bacteria will develop invasive GAS disease. Although healthy people can get invasive GAS disease, those at higher risk include:

  • the elderly
  • infants
  • those living in a group-setting
  • those with chronic illnesses like cancer, diabetes and kidney dialysis 

How is GAS disease treated?

  • GAS infections are treated with antibiotics. 
  • It is important to complete the entire antibiotic treatment, even when you start feeling better.
  • For those with very severe illness, hospitalization may be required.


  • Clean your hands often with soap and water or use an alcohol-based hand rub with at least 70% alcohol.
  • Persons with a very sore throat (and no respiratory symptoms such as cough) should see their health care provider to be tested.  A throat swab will be done to find out if the illness is strep throat. 
  • Persons infected with strep throat should stay home from work, school, or day care until 24 hours after starting an antibiotic.  It is important to complete the entire antibiotic treatment as ordered by your health care provider.
  • All wounds (breaks in skin such as a cut or scratch) should be kept clean and covered. Watch for signs of infection such as warm skin, sudden or worsening redness, red streaking, swelling, pus, drainage, pain and fever. 
  • A person with signs of an infected wound should see their health care provider right away.
  • Close contacts of an invasive GAS case are contacted by Public Health Services to talk about the need for preventative antibiotics. Not all contacts require antibiotics.
  • Close contacts will be asked to self-monitor for signs and symptoms of GAS infection including fever for 30 days and to see their health care provider if they develop symptoms.

Contact us

If you have any questions, please contact the Infectious Disease Program at 905-546-2063