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Group A Streptococcus (GAS)

Group A Streptococcus (GAS) diseases are caused by a germ (bacterium) called Streptococcus pyogenes that spreads between people through direct contact with secretions from the nose, throat, wounds, or respiratory droplets.  

Most illnesses of this kind are mild or moderate and can include: 

  • Strep throat (sore throat) 
  • Impetigo and other skin infections 
  • Scarlet fever (sore throat, fever and rash). 

In rare cases, GAS infections become invasive and cause severe, life-threatening illness after bacteria enters the blood, lungs, muscles, joints, bones, organs, or the fluid surrounding the brain and spinal cord.  

Examples of “invasive” group A Streptococcus (iGAS) diseases that can make people very sick include: 

  • “Flesh-eating disease”, or necrotizing fasciitis, a rapidly progressing infection that destroys muscles, fat and skin tissue. 
  • Pneumonia due to invasive GAS 
  • Meningitis due to invasive GAS 
  • Streptococcal toxic shock syndrome, when bacteria produce toxins that cause a sharp drop in blood pressure and leads to organs like the kidneys, liver or lungs to stop working properly.  

GAS and iGAS infections are treated with antibiotics. 

Some people may carry germs that cause GAS in their throat or on their skin with no signs or symptoms of infection.  People who are carriers of GAS can still transmit the bacteria to others even if they aren’t sick.  

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