What Causes Ear Infections?

When you hear about an ear infection, it usually refers to a middle ear infection, wherein your middle ear gets inflamed. The middle ear is the part of the ear just behind the eardrum. Ear infections are most commonly caused by bacteria and viruses.

An ear infection can either be acute or chronic. An acute ear infection is when it lasts for a short period of time. However, chronic ear infections tend to remain for long or recur quite often. Ear infections are more common in small children as they have short and more horizontal eustachian tubes. 5 out of 6 children will have an ear infection before their third birthday.

Three Parts of the Ear

• Outer ear - or the pinna is the part of the ear that is visible to you. It also consists of the external ear canal, which begins at the opening of the ear and goes all the way up to the eardrum. The eardrum is a small membrane that separates the outer ear from the middle ear. The main function of the outer ear is to filter and transmit sound waves towards the middle ear. If the outer ear is infected, it is known as the swimmer's ear or otitis externa.

• Middle ear - is the part that is just behind your eardrum. It consists of three tiny bones called as malleus, incus and stapes that transmit the sound vibrations from the eardrum to the inner ear. The middle ear is also connected to the back of your throat via a small connection called the eustachian tube. If the middle ear gets infected, it is known as otitis media or simple middle ear infection.

• Inner ear - consists of the cochlea and the vestibular system that play a big role in maintaining our balance. These structures contain nerve endings that will carry the sound signals to our brain. Their functions are hearing and balance. If the inner ear is inflamed, it is known as otitis interna, labyrinthitis or vestibular neuritis.

What are the causes of an ear infection?

An ear infection occurs when your eustachian tube gets blocked and results in the collection of fluid in the middle ear. The eustachian tube is a small tube that connects the middle ear to the back of your throat. Its function is to drain any accumulated secretions in the middle ear and also to maintain the middle ear pressure at near normal levels of the environmental air pressures. The following are the causes of ear infections:

• Viruses and bacteria - these are the most common causes of ear infections. The infection usually follows an upper respiratory tract infection, which will drive the organisms to the middle ear via the eustachian tube.

• Blood-borne infection - this type of infection can be initiated from any part of the body that can cause an ear infection when the organisms reach the ear.

• Infection due to an external source – scratching the ear or when water enters your ear can both lead to an ear infection.

There are several other causes of an ear infection and these include sinusitis, allergies, cold, infected or swollen adenoids, and smoking.