Cause
Strep throat is
caused by streptococcal (strep) bacteria, most often by group A beta-hemolytic
streptococcus (GABS). Other types of strep that can sometimes infect the throat
are groups C and G strep bacteria.
A strep infection causes the
throat (pharynx) and the
tonsils or adenoids to become irritated,
inflamed, and painful.
Sore throats are
most commonly caused by
viral infections or other irritants such as smoke,
allergies, dry air, or a throat injury, and not by a strep infection. For more
information, see the topic
Sore Throat.
How the strep infection is spread
Strep throat can
be passed from person to person. When a person infected with strep throat
breathes, coughs, or sneezes, tiny droplets containing the strep bacteria are
released into the air and are breathed in by other people.