Group A streptococcal diseases (Streptococcus pyogenes)

Diseases caused by Group A streptococcus

On this page

• About Group A streptococcal diseases
• Where Group A streptococcus bacteria are found
• The spread of Group A streptococcus bacteria

About Group A streptococcal diseases

The group A streptococcus bacteria can cause many Group A streptococcal (GAS) diseases. Most illnesses are mild and may include:

• strep throat
• sinus infections
• skin or wound infections
• fever and rash (scarlet fever)

In rare cases, a GAS infection can lead to invasive, more severe disease. This is known as invasive GAS or iGAS disease. These can include:

• lung infections, such as pneumonia
• flesh-eating disease (necrotizing fasciitis), which is a quickly progressing infection that destroys skin and muscle tissues
• toxic shock syndrome, which occurs when the bacteria produce toxins that could cause organs in the body to stop functioning

In rare cases, some people may develop other complications after being infected with Group A streptococcus bacteria. These may include:

• severe muscle pain and tenderness (myalgia)
• kidney disease (post-streptococcal glomerulonephritis)
• inflammation of the joints, heart, skin and central nervous system (acute rheumatic fever)

Where Group A streptococcus bacteria are found

The bacteria that cause GAS diseases can normally be found:

• on the skin
• in the throat

Some people can carry these bacteria with no signs or symptoms of infection.

iGAS develops when GAS bacteria enter parts of the body where bacteria are not normally found, such as:

• blood
• muscles
• bones and joints
• fluids surrounding 
  • the brain
  • the spine
  • the lungs
  • other internal organs

The spread of Group A streptococcus

GAS bacteria can be spread by direct contact with:

• infected wounds on the skin
• fluids from the nose or throat of infected persons, such as when an infected person coughs or sneezes