Causes

Strep throat is caused by infection with a bacterium known as Streptococcus pyogenes, also called group A streptococcus.

Streptococcal bacteria are contagious. They can spread through droplets when someone with the infection coughs or sneezes, or through shared food or drinks. You can also pick up the bacteria from a doorknob or other surface and transfer them to your nose, mouth or eyes.