Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock () or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

Group A Streptococcal Infections

(Streptococcus pyogenes)

Group A streptococcus (group A strep) is a type of bacteria (Streptococcus pyogenes) that commonly lives on a person’s skin or in their nose and throat. Many people carry the bacteria without ever getting sick. However, group A strep bacteria can sometimes cause infection. While most infections are mild like strep throat, the bacteria can sometimes cause life threating “invasive infections”. Invasive infections occur when the bacteria invade parts of the body where it is normally not found, such as the brain or muscles.

Doctor checking a child's throat

Group A Strep 101

Group A strep bacteria can spread when someone has direct contact with the respiratory droplets of an infected person. Someone can also become infected if they have contact with infected wounds or sores. A person who has group A strep on their skin or in their nose or throat can spread the bacteria even if they do not feel sick. However, they are less likely to spread the bacteria than someone who has an active infection.

Group A strep infection can cause many different types of illnesses that can be mild or severe.  

Mild illnesses caused by Group A strep include:

  • Strep throat – An infection that causes sore throat with fever.
  • Impetigo – A skin infection that causes open sores that drain clear fluid or pus.
  • Scarlet fever – An infection characterized by a raised rash that feels like sandpaper.

Severe illness can occur when the bacteria “invades” other parts of the body like the blood, lungs, fat, muscles, or the brain. Severe illnesses include: 

  • Pneumonia – An infection in the lungs that can make it difficult to breathe.
  • Meningitis – Inflammation of the brain and spinal cord.
  • Streptococcal Toxic Shock Syndrome – A blood infection that can cause organ failure.
  • Necrotizing Fasciitis – A fatal infection that causes skin and muscle tissue to die.

Group A strep infections can be treated with many different antibiotics. Early diagnosis and treatment can help prevent severe illness and death.

Practicing good hand hygiene is one of the best ways to prevent group A strep infections. It is especially important to wash your hands with soap and water after coughing and sneezing and before preparing foods and eating. Keep any open wounds clean and monitor them for signs of infection. People with sore throats should also get tested for strep throat and stay home while they are sick.

Provider Information

This is a Wisconsin disease surveillance category II disease:

Wisconsin case reporting and public health follow-up guidance:

Questions about Group A Streptococcal Infections? Contact us!
Phone: 608-267-9003 | Fax: 608-267-9009

Wisconsin Local Health DepartmentsRegional officesTribal agencies

Last revised January 3, 2023