Tonsillitis is caused by virus or bacterial infection. When people are exposed to a new virus, upper respiratory tract infection can occur. Upper respiratory tract infection can lead to tonsillar inflammation of patients, which can be accompanied by bacterial infection on the basis of viral infection. Bacteria can be parasitized in the recess of human tonsil, and patients will not be infected when the human body has normal resistance. However, when the resistance of the human body decreases, the bacteria in the tonsils can invade the tonsils, causing tonsillar inflammation. Some infectious diseases, such as measles, rubella, scarlatina and other diseases, can also lead to tonsillitis.