Key points
- Group A Streptococcus (group A strep bacteria) can cause many different infections.
- These infections range from minor to serious.
- Group A strep bacteria can also cause inflammatory diseases.
- Group A strep bacteria are contagious.
- Generally, people spread the bacteria to others through respiratory droplets or direct contact.
![A computer-generated image of group A Streptococcus based on scanning electron microscopic imagery.](/https/www.cdc.gov/group-a-strep/media/images/Spyogenes.png)
Types
Group A strep bacteria can cause many different types of infections that range from minor to serious. The bacteria can also cause inflammatory diseases.
The following are some, but not all, of the conditions associated with group A strep bacteria.
Minor infections
The following infections caused by group A strep bacteria are generally mild:
Serious infections
Three infections caused by group A strep bacteria can be very serious and even deadly:
Inflammatory diseases
Long-term health issues related to group A strep bacteria include:
Both are thought to be caused by an immune response to an earlier group A strep infection. As the body's defense system, the immune system is important in fighting off infections. But the immune system can mistakenly attack healthy parts of the body and cause damage.
Risk factors for serious infections
Who's at increased risk of getting any specific condition listed above varies. However, some people are generally at increased risk of getting a serious group A strep infection.
Viral infections, like flu or chickenpox, can increase this risk.
Medical conditions that can increase the risk for getting a serious group A strep infection include:
- Cancer
- Chronic heart, kidney, or lung disease
- Diabetes
- Immunocompromising condition (having a weakened immune system)
- Wounds or skin disease
Other groups at increased risk for getting a serious group A strep infection include:
- American Indian and Alaska Native populations
- People aged 65 years or older
- People who inject drugs or who are experiencing homelessness
- Residents of long-term care facilities
How it spreads
Group A strep bacteria are very contagious. Some people infected with group A strep bacteria don't have symptoms or seem sick. They can still spread the bacteria to others.
Generally, people spread the bacteria to others through respiratory droplets or direct contact. Rarely group A strep bacteria can be spread through food that isn't handled properly.
Respiratory droplets
Group A strep bacteria often live in the nose and throat. People who are infected spread the bacteria by talking, coughing, or sneezing. This creates respiratory droplets that contain the bacteria.
People can get sick if they:
- Breathe in respiratory droplets that contain the bacteria
- Touch their mouth or nose after touching something with those droplets on it
- Use the same plate, utensils, or glass as someone infected with the bacteria
Once washed, plates, utensils, and glasses are safe for others to use.
Direct contact
People can also spread group A strep bacteria from infected sores on the skin. Other people can get sick if they touch those sores or come into contact with fluid from the sores.
Once the sores heal, someone with impetigo usually isn't able to spread the bacteria to others.
Prevention
There are things people can do to protect themselves and others from group A strep infections.
Group A strep prevention activities vary by each disease, but generally focus on three important goals:
- Limit exposure and spread of bacteria
- Treat group A strep infections promptly
- Use preventive antibiotics when appropriate