 Streptococcal pharyngitis , also known as strep throat , is an infection of the back of the throat including the tonsils caused by group A streptococcus . Common symptoms include fever , sore throat , red tonsils , and enlarged lymph nodes in the neck . A headache , and nausea or vomiting may also occur . Some develop a sandpaper @-@ like rash which is known as scarlet fever . Symptoms typically begin one to three days after exposure and last seven to ten days . 
