Ear infections, specifically infections of the middle ear, are common childhood infections in industrialized countries and the leading cause of outpatient antimicrobial treatment of children in the United States. Infections of the middle and inner ear can cause temporary or permanent loss of hearing and associated speech and language delays. The World Health Organization estimates that in developing countries, 51,000 children under 5 years of age die annually from complications of infections of the middle ear. There are three types of ear infections characterized by location in the ear.
Infection of the middle ear is known as otitis media and is characterized by infected fluid behind the eardrum. Otitis is the Latin word for inflammation of the ear. The eardrum separates the inner ear from the ear canal. Infections of the middle ear are defined by acute otitis media, a middle ear infection with both effusion, or fluid, and presence of signs or symptoms of an acute infection, or by otitis media with effusion, a middle ear infection with effusion and without signs or symptoms of an acute infection.
Signs and symptoms of acute otitis media include pulling of the ear in an infant, irritability in an infant or toddler, discharge from the external ear, and fever. By 3 years of age, 50 to 85 percent of children in the United States have had acute otitis media with peak incidence between ages 6 and 11 months. Recurrent acute otitis media infections, defined as three or more episodes of infection, affect 10 to 20 percent of children by 1 year of age. Children with recurrent acute otitis media infections may have a surgical treatment, myringotomy, whereby a small tube is placed inside the affected ear by an otolaryngologist.
Infections of the middle ear are caused by Eustachian-tube dysfunction, bacterial infection, viral infection, or immune response to infection. Common bacterial infections include _Streptococcus pneumoniea_, _Moraxella catarrhalis_, and nontypeable _Haemophilus influenzae_. Risk factors for infections of the middle ear include young age (less than 2 years old), daycare attendance, having older siblings, fall and winter season, impaired immune system, genetic predisposition, and family history.
Acute otitis media spontaneously resolves, without treatment, within 2 to 14 days in 80 percent of children between 2 and 12 years of age. Antibiotic treatment is recommended for children without improvement in symptoms following 48 to 72 hours of observation. Infection of the outer ear is known as otitis externa and is characterized by infected fluid in the ear canal. Infection of the outer ear is also known as swimmer’s ear. Infections of the outer ear are defined by acute or chronic forms. Acute otitis externa is generally diagnosed by signs and symptoms of a bacterial infection, such as an odorless secretion from the ear, itching, and pain.
Chronic otitis externa is commonly due to a fungal infection or allergic reaction, generally due to an inflammation of the skin of the ear canal. Acute otitis externa affects 4 in 1,000 people annually in the United States, is most common in children 7-12 years of age, and is associated with high humidity, warmer temperatures, swimming, local trauma in the ear, and hearing aids. Chronic otitis externa affects 3 to 5 percent of the population in the United States. Treatments for infections of the outer ear include topical therapy and amelioration of inciting factors.
Twenty-five percent of individuals treated for otitis externa will also be given an antibiotic. Infection of the inner ear is known as otitis interna or labyrinthitis. Inner ear infections can be caused by bacterial infections such as meningitis or syphilis (either congenital or acquired). Viral infections also cause infections of the inner ear through congenital infection, as part of a systemic viral illness, or an isolated involvement of the inner ear. Confirmed associations have been identified between infections of the inner ear and cytomegalovirus (congenital infections) and mumps (acquired).
Cytomegalovirus is considered the most common congenital infection in the United States and the most common infectious cause of congenital deafness. Suspected pathogens associated with infection of the inner ear include rubella (congenital), rubeola, influenza, varicella-zoster, EBV, poliovirus, RSV, adenovirus, parainfluenza, and herpes simplex viruses. Congenital infection with the protozoa, toxoplasmosis, also leads to inner ear infections. Fungal infections of the inner ear are rare unless an individual is immunocompromised.
Symptoms of infections of the inner ear include dizziness, vertigo, ringing in the ears, and hearing loss. Idiopathic sudden sensorineural hearing loss in an otherwise health individual is usually due to a viral inner ear infection. Approximately 30 to 70 percent of patients will have partial or complete recovery of hearing with proper treatment. ?
References
- David Osguthorpe and David R. Nielsen , “Otitis Externa: Review and Clinical Update,” American Family Physician (v. 74/9 , 2006)
- Maroeska M. Rovers , et al. , “Otitis Media,” Lancet (v. 363 , 2004).