Group A Streptococcus (GAS) Infections

What is group A streptococcus (GAS)?

Group A Streptococcus is a bacterium found in the human throat or on the skin. There are approximately 350 cases of invasive GAS infection reported in Illinois each year.

What kind of illnesses does GAS infection cause and what are the symptoms?

Some persons with GAS infections experience no signs or symptoms. For those with symptoms, the most common illnesses are “strep throat,” a skin infection called impetigo and scarlet fever. Symptoms of these illnesses are described below.

  • "Strep throat," – swollen tonsils possible covered with a grayish-white film, swollen lymph nodes, fever with or without chills, painful swallowing and headache.
  • Impetigo - mild skin infection accompanied by open, draining sores and other general symptoms of GAS infection such as fever, swollen lymph nodes and a sore throat.
  • Scarlet fever - characterized by a fever, sore throat, red sandpaper-like rash and a red "strawberry" tongue. It is caused by several different strains of the streptococcal bacteria, all of which produce a toxin that cause the characteristic red rash.

Anyone suspected of having an infection with Group A Streptococcus should immediately seek medical care for testing and treatment. Though common, GAS infections can become very serious if untreated.

What are the complications of GAS infections?

  • Glomerulonephritis is a rare but serious complication of streptococcal infection that limits your kidney’s ability to remove waste from your blood. Symptoms include blood in urine, frothy or foamy urine and swelling in your feet, ankles, legs, abdomen or face.
  • Untreated strep throat or an incomplete antibiotic course can result in rheumatic fever. Rheumatic fever is rare but serious as it causes permanent damage to the heart’s valves.

Types of GAS Infections

GAS infections can sometimes cause invasive disease, including pneumonia, meningitis, infection of the skin and muscle (necrotizing fasciitis) as well as an illness resembling toxic shock syndrome (Streptococcal Toxic Shock Syndrome or STSS). Though relatively uncommon, these invasive infections can progress rapidly and be life threatening.

Persons at higher risk for invasive disease include those with:

  • chronic conditions (diabetes, cancer),
  • compromised immune systems (receiving chemotherapy, autoimmune disorders or HIV infection) or
  • open wounds or sores that allow the bacteria to enter the tissue.

It also is believed that infection with certain strains of Group A Streptococcus increases the likelihood of invasive disease.

What are signs of necrotizing fasciitis and Streptococcal toxic shock syndrome (STSS)?

Necrotizing fasciitis:

  • Severe pain and swelling, often rapidly increasing
  • Fever
  • Redness at a wound site


  • Fever
  • Abrupt onset of generalized or localized severe pain, often in an arm or leg
  • Dizziness with or without confusion
  • Influenza-like syndrome

How is GAS spread?

GAS can be spread from any individual who harbors the bacteria even if they do not have any symptoms. Persons without symptoms are usually less contagious. The bacteria are transmitted from person to person by direct contact with mucus or secretions (e.g. nasal secretions) from an infected person. Transmission occurs less frequently through contact with articles handled by an infected person. The time from exposure to illness is one to three days.

Untreated individuals can be contagious for 10-21 days or longer. An infected person is typically no longer infectious after the first 24 hours of appropriate treatment.

How can GAS be treated?

Group A Streptococcus bacteria can be treated with several different antibiotics. As with any antibiotic use, it is important to complete the entire course as prescribed by your health care provider.

Is there any way to reduce the chances of getting a GAS infection?

As with most communicable diseases, the spread of group A Streptococcus infections may be reduced by good hygiene. Effective hand washing after coughing or sneezing and before preparing foods or eating is essential ( Persons with fever and sore throats should be seen by a doctor for testing. If GAS infection is diagnosed, the person should stay home from work, school or day care until fever free and 24 hours or more after taking an antibiotic.

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Illinois Department of Public Health
535 West Jefferson Street
Springfield, Illinois 62761
Phone 217-782-4977
Fax 217-782-3987
TTY 800-547-0466
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