An infection in the outer ear and ear canal is called otitis externa.
Ear infection causes vary, but one known factor is genetics, as ear infections tend to run in families. Additional causes for otitis (a general term for infection or inflammation of the ear) vary depending on whether they occur in the outer ear or the middle ear.
Though adults may suffer from ear infection, it occurs more frequently in young children. According to the National Institute on Deafness and Other Communication Disorders, 75 percent of children will have at least one ear infection by the time they are three years of age.
According to the University of Maryland Medical Center, a middle ear infection, or otitis media, is the most common type of ear infection. Acute otitis media (AOM) is caused by viral or bacterial infections that spread to the middle ear, where the ear lining becomes swollen and fluid is trapped behind the eardrum. AOM may occur in an individual who is already suffering from a cold. As AOM progresses, mucus will drain from the ear. If it remains trapped in the ear after the infection is over, however, the ear may have difficulty fighting off new infections. Thus, a previous case of middle ear infection may make an individual more susceptible to infection in the future.
According to the American Academy of Pediatrics, ear infection is the second most common illness in children, preceded by the common cold. A childs less-developed immune system, which has more difficulty fighting infections, increases a childs likelihood of getting a middle ear infection.
The Eustachian tube, the small passageway connecting the middle ear to the upper part of the throat, is shorter and narrower in a child, making it more easily blocked and, therefore, more prone to infection.
As well, the adenoids in a child are larger than in an adult, and this makes them more vulnerable to inner ear infection. The larger-sized adenoids can more likely interfere with the Eustachian tube opening and more likely become infected. An infection of the adenoids may then spread to the Eustachian tubes.
An infection in the outer ear and ear canal, which is called otitis externa or swimmers ear, occurs when the defenses in the ear canal have broken down, giving water-loving bacteria, or occasionally fungi, easier access. The ear canals defenses may be lowered by excess moisture in the ear as a result of swimming, humid weather or water from another source that gets trapped in the ear. Swimming in dirty water can also cause ear infection.
Another cause of an outer ear infection is scratching inside the ear, usually from an object stuck in the ear. For example, an individual trying to clean wax from the ear canal with a cotton swab or other small object may inadvertently irritate or damage the ear, leading to the development of an infection in the ear canal.
Additionally, individuals who are sensitive to hair products or jewelry may develop a rash that leads to an outer ear infection. Occasionally, swimmers ear is associated with a middle ear infection, dry skin, eczema or colds. When these conditions lead to moisture in the ear, the ear canal may be more prone to infection.