Tonsillitis is an infection of the tonsils, which are the two masses of tissue located at the back of the throat on each side. Tonsils act as filters or goalies to prevent and trap germs from entering the airways and causing infection. They also produce antibiotics to kill bacteria. Tonsillitis occurs when too many germs and bacteria enter through the mouth and overwhelm the tonsils. As tonsillitis is highly contagious, it is especially prevalent in children.
Tonsillitis is caused by either a viral or bacterial infection that enters the body through the mouth. It can be due to the common cold, which is a viral infection, or strep throat, which is a bacterial infection. The American Academy of Family Physicians estimated that up to thirty percent of cases are due to the strep bacteria; therefore, viral infections are the most common cause of tonsillitis. It can also be caused by the Epstein-Barr virus, which is the virus responsible for mononucleosis.