Inflammation of the salivary gland, which is a symptom of an infection, often caused by bacteria, that develops in the gland as the result of an obstruction of the duct, or tube, that carries saliva from the gland into the mouth. The obstruction may be due to salivary glands stones in the duct or to abnormalities in the duct system of the major salivary glands; the ducts may have small constrictions or narrowings that interfere with the normal flow of saliva. Infections of the salivary glands may also be caused by a virus.