Cause
Possible causes of otitis externa, which may lead to infections of the middle and inner ear, include excess moisture in the ears due to swimming or bathing; inappropriate treatment or cleaning of the ears such as may be caused by the use of cotton-tipped applicators; excess wax production in the ears; an underlying disease; or a foreign body that is obstructing the ear canal. Additionally, otitis externa can be caused by a host of parasites, including ear mites, mange, fly bites, and fleas. Allergies and illnesses such as autoimmune diseases may also lead to otitis. The most common cause of the development of otitis media and otitis interna is a bacterial infection resulting from otitis externa.