Streptococcal sore throat (strep throat), is an infection of the mucous membranes lining the throat. Sometimes the tonsils are also infected (tonsillitis).

Caused by group A Streptococcus bacteria, untreated strep throat may develop into rheumatic fever or other serious conditions.

Strep throat accounts for between 5% and 10% of all sore throats. It occurs most often between November to April, and while anyone can get strep throat, it's most common among school children. People who smoke or who are tired, run down, or who live in damp, crowded conditions are more likely to become infected. Children under age 2 and adults who aren't around children are less likely to get the disease.

The disease passes directly from person to person by coughing or sneezing; rarely the bacteria is passed through food if a sick food handler accidentally contaminates food by coughing or sneezing. Statistically, if someone in the home...