GAS Frequently Asked Questions
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- What is group A Streptococcus (GAS)?
- How are group A streptococci spread?
- What kind of illnesses are caused by group A streptococci?
- How common is invasive group A streptococcal disease?
Q: What is group A Streptococcus (GAS)?
A: Group A Streptococcus is a bacterium that can cause a wide range of infections. People may also carry group A streptococci in the throat or on the skin and have no symptoms of illness. Most GAS infections are relatively mild illnesses such as "strep throat," or impetigo (a skin infection). Occasionally these bacteria can cause severe and even life-threatening diseases.
Q: How are group A streptococci spread?
A: These bacteria are spread through direct contact with mucus from the nose or throat of people who are sick with a GAS infection or through contact with infected wounds or sores on the skin. The bacteria may also be spread through contract with persons without symptoms but who carry the bacteria in their throat or on their skin. Ill persons, such as those who have strep throat or skin infections, are most likely to spread the infection. Persons who carry the bacteria but have no symptoms are much less contagious. Treating an infected person with an antibiotic for 24 hours or longer generally prevents the spread of the bacteria to others. However, it is important to complete the entire course of antibiotics as prescribed. It is not likely that household items like toys spread these bacteria. However, it is possible to spread these bacteria by drinking from the same glass or eating from the same plate as someone who is ill with a GAS infection like strep throat.Top of Page
Q: What kind of illnesses are caused by group A streptococci?
A: Infection with GAS can result in a range of illnesses:
- Mild illness such as strep throat or impetigo
- Severe illness such as pneumonia, necrotizing fasciitis, or streptococcal toxic shock syndrome
Severe, sometimes life-threatening GAS disease may occur when these bacteria get into parts of the body where bacteria usually are not found, such as the blood, muscle, or the lungs. These infections are called "invasive GAS disease." Two of the most severe, but least common, forms of invasive GAS disease are necrotizing fasciitis and streptococcal toxic shock syndrome (STSS). Necrotizing fasciitis (occasionally described by the media as "the flesh-eating bacteria") rapidly destroys muscles, fat, and skin tissue. STSS causes blood pressure to drop rapidly and organs (e.g., kidney, liver, lungs) to fail. STSS is not the same as the staphylococcal toxic shock syndrome that has been associated with tampon usage. Less severe invasive illnesses caused by GAS include cellulitis and pneumonia. In the U.S, about 25% of patients with necrotizing fasciitis due to GAS and approximately 40% with STSS die. About 10%-15% of patients with any form of invasive group A streptococcal disease die.
Q: How common is invasive group A streptococcal disease?
A: Approximately 9,000-11,500 cases of invasive GAS disease occur each year in the United States, resulting in 1,000-1,800 deaths annually. STSS and necrotizing fasciitis are each responsible for an average of about 6%-7% of these invasive cases. In contrast, there are several million cases of strep throat and impetigo each year.
Q: Who is most at risk of getting invasive group A streptococcal disease?
A: Few people who come in contact with GAS will develop invasive GAS disease. Most people will have a throat or skin infection, and some may have no symptoms at all. Although healthy people can get invasive GAS disease, people with chronic illnesses like cancer, diabetes, and chronic heart or lung disease, and those who use medications such as steroids have a higher risk. People with skin lesions (such as cuts, chickenpox, or surgical wounds), the elderly, and adults with a history of alcohol abuse or injection drug use also have a higher risk for disease.Top of Page
Q: What are the early signs and symptoms of necrotizing fasciitis and streptococcal toxic shock syndrome?
A: Early signs and symptoms of necrotizing fasciitis include:
- Severe pain and swelling, often rapidly increasing
- Redness at a wound site
Early signs and symptoms of STSS include:
- Sudden onset of generalized or localized severe pain, often in an arm or leg
- Flu-like symptoms such as fever, chills, muscle aches, nausea, vomiting
- A flat red rash over large areas of the body (only occurs in 1 in 10 cases)
Q: How is invasive group A streptococcal disease treated?
A: GAS infections can be treated with many different antibiotics. For STSS and necrotizing fasciitis, high dose penicillin and clindamycin are recommended. For those with very severe illness, supportive care in an intensive care unit may also be needed. For people with necrotizing fasciitis, early and aggressive surgery is often needed to remove damaged tissue and stop disease spread. Early treatment may reduce the risk of death from invasive group A streptococcal disease. However, even the best medical care does not prevent death in every case.
Q: What can be done to help prevent group A streptococcal infections?
A: The spread of all types of GAS infection can be reduced by good hand washing, especially after coughing and sneezing and before preparing foods or eating. People with sore throats should be seen by a doctor who can perform tests to find out whether the illness is strep throat. If the test result shows strep throat, the person should stay home from work, school, or day care until 24 hours after taking an antibiotic. All wounds should be kept clean and watched for possible signs of infection such as redness, swelling, drainage, and pain at the wound site. A person with signs of an infected wound, especially if fever occurs, should immediately seek medical care. It is not necessary for all persons exposed to someone with an invasive group A strep infection (i.e., necrotizing fasciitis or STSS) to receive antibiotic therapy to prevent infection. However, in some situations, antibiotic therapy may be recommended. That decision should be made after talking with your doctor.Top of Page
- Page last reviewed: May 1, 2014
- Page last updated: May 1, 2014
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