Strep throat is a bacterial infection of the throat caused by Streptococcus pyogenes, a group A strep. It is a contagious infection that causes the throat to get inflamed, sore, and itchy. The condition is marked by swollen tonsils with white patches, swollen lymph nodes on the neck, fever, rashes, and headache. Due to the soreness, swallowing food can be particularly painful to do.
Both strep throat and influenza (flu)  can sometimes be taken to mean the same thing. They aren’t. The confusion may be due to the fact they both share some early symptoms such as a runny nose, sore throat, and fever. While the flu is caused by a virus, strep throat is caused by bacteria. Cold also doesn’t typically accompany strep throat. When this happens, it is not caused by strep A.
Strep throat affects people of all ages but is most prevalent in children. Transmission is through droplets carried in the air when someone sick with strep A bacteria sneezes or coughs. The droplets may also be passed through sharing of food or unwashed eating utensils.
Untreated strep throat can result in serious complications if left untreated. These complications include rheumatic fever which can cause damage to the heart valve and inflammation of the joints.
Some conditions may predispose one to strep throat.