Group A streptococcus is most notable for its ability to cause strep throat and skin infections. Complications of Strep A infections include rheumatic fever and post-streptococcal glomerulonephritis. Neither condition is an infection, but rather is caused by the body's immune system accidently attacking the heart or kidney while trying to destroy the strep. Group A streptococcus produces toxins as it grows in the body. These toxins affect the red blood cells, causing a rash such as that observed in scarlet fever.
Many people carry strep A in their nose and throat areas and never actually become ill.
When a carrier sneezes or coughs, strep A bacteria float into the air, to be inhaled by the closest person. Although most strep A infections are self-limiting, most infected individuals can be successfully treated by a course of antibiotic therapy. Although rare, strep A infections can cause spreading skin infections in susceptible people and, if left untreated, can eventually cause death. In these cases, with supportive therapy and intravenous antibiotics, death is usually averted. Most physicians choose to treat strep A infections immediately, in order to avoid the possibility of unforeseen complications.