Strep throat is an infection of the pharynx caused by the bacteria Streptococcus pyogenes. The pharynx is the part of the throat between the tonsils and the larynx, or voice box.

What is going on in the body?

Strep throat is the most common of the many infections that are caused by group A streptococci, or GAS. The bacteria that causes strep throat makes a toxin that results in an infection in the throat and tonsils. A person can develop symptoms of strep throat from 1 to 6 days after being exposed to the bacteria. Symptoms in up to 40% of children may be too mild to diagnosis. Up to 20% of school-aged children may be carriers of the bacteria. These children will show no symptoms but can transmit strep throat to others.

A sore throat accompanied by fever is caused by a virus 70% of the time. Without treatment, uncomplicated viral infections usually subside within 3 to 10 days after onset. Strep throat is more significant because of the increased incidence of complications.

What are the causes and risks of the disease?

Strep throat is a bacterial infection that is usually spread by person-to-person contact through coughing or sneezing. Exposure to a person who has untreated strep throat may pose a risk for acquiring this infection. A person may be a carrier of the strep bacteria without having symptoms.

People who may be more at risk for serious strep infection include the following: