Parotitis epidemiology and demographics

Overview
Parotitis is an inflammatory disorder of the salivary gland, or sialadenitis. It is most commonly infectious in etiology but can be autoimmune or neoplastic.

Epidemiology and demographics
The first report of acute bacterial sialadenitis dates back to 1828 described in a 71-year-old man whose infection progressed to gangrene. President Garfield died from acute parotitis complicating abdominal surgery. Parotitis carried an 80% mortality rate in the 1800s and remains a quite morbid infection with estimated mortality of 20-50% in the present day.

Acute infection can occur in any salivary gland but the most commonly affected one is the parotid. This is thought to be due to a combination of anatomic and physiologic factors. The saliva from the parotid is less mucoid than that from the other salivary glands. IgA, lysozyme and sialic acid are all found in smaller amounts in the more viscous parotid secretions. These substances are thought to help fight off ascending bacterial infection. Bacterial parotitis is generally unilateral in adults (75-90%), while viral is generally bilateral.

Though 80-90% of salivary calculi occur in the Wharton’s duct of the submandibular gland, the parotid remains the most common site of acute suppurative salivary infection. The secretions from the submandibular gland are more alkaline, thought to result in a higher concentration of insoluble calcium phosphate.