Group A streptococcal (strep) infections are caused by group A Streptococcus, a type of bacteria responsible for a variety of health problems.
These infections can range from relatively mild illnesses such as strep throat, scarlet fever, and impetigo (a skin infection) to life-threatening conditions such as toxic shock syndrome and necrotizing fasciitis (“flesh-eating” infection). Most people are familiar with strep throat, which along with impetigo is the most common form of the disease.
Health experts estimate that more than 10 million mild throat and skin infections like these occur every year. Serious, sometimes life-threatening, illness may occur when bacteria get into parts of the body where bacteria usually are not found, such as the blood, muscles, or the lungs. These infections are termed "invasive group A strep disease."