I've seen a fair number of cases of swimmer's ear in the last few weeks. We tend to see more cases of this in hot, humid weather, but it can also be brought on by other conditions.

The medical term for swimmer's ear is otitis externa, indicating inflammation of the external ear. This is in contrast to the more common otitis media, or inflammation of the middle ear (the part of the ear behind the ear drum).

The number of people who suffer from swimmer's ear is about four per 1,000 per year, or about three to five percent of the population. It afflicts males and females in equal numbers and tends to present between seven and twelve years of age.

A layer of wax or "cerumen" protects the external ear canal. There exists a delicate balance of too much or too little cerumen. If there is not enough present, the ear canal can dry out, crack and develop infection. If there is too much, the ear canal can become too moist. This leads to swelling and breakdown of the skin lining the canal.

The majority of cases of swimmer's ear are caused by too much wax. This allows water contaminated with bacteria or fungi to enter the ear canal and invade the broken down skin. Since swimmers often swim in contaminated water, they are more prone to develop this problem.

There are other conditions that predispose one to develop otitis externa. One of the more common is trauma to the ear canal. This is where one should heed grandma's advice to not put anything smaller than an elbow in your ear. Items such as Q-tips, bobby pins, paper clips and pencils do not belong in the ear canal. Repeated use of earplugs or hearing aids can also cause trauma and trapping of moisture.

There are other skin conditions such as dermatitis and seborrhea that can increase the risk for infection. People with small ear canals are also at increased risk.

The most common organisms that cause otitis externa are Pseudomonas bacteria. Staphylococci and Streptococci can also cause problems. Fungi play a role in about five percent of cases.

Most people recover from otitis externa with minimal intervention. However, people with certain medical conditions can develop severe problems. Diabetics and those who have compromised immune systems need to be careful. Simple otitis externa can lead to a severe condition called malignant otitis externa.

The malignant form can result in the infection spreading to the tissues around the ear. It should be suspected in those who have a lot of redness around the ear or swelling of the ear itself. These people need hospitalization for intravenous antibiotics. If left untreated, this condition can be fatal in half the sufferers.

The history of someone with swimmer's ear usually involves some water exposure. Itching may develop followed by worsening pain over the next couple of days. The ear may start to drain white material.

Patients may experience a pressure or fullness and can also develop hearing loss as the ear canal swells shut. A reliable physical finding is pain when one tugs on the earlobe, which is usually not the case in middle ear infections.

Treatment is curative over 90 percent of the time. Most people improve in 2-3 days and are back to normal in a week or so.

There are many treatments available, but prescription antibiotic drops work best. One of the oldest agents around is a milky fluid that contains two different antibiotics and a steroid. However, one of the antibiotics can sometimes cause some hearing loss and the other antibiotic may cause a local allergic reaction.

The antibiotic drops ciprofloxacin and ofloxacin are two that are usually recommended. If there is fungal involvement, doctors may prescribe simple acetic acid (vinegar) solutions or topical antifungal medication. Occasionally the pain is so intense that oral narcotics may be required.

Patients who get swimmer's ear frequently should use measures to prevent the problem. A half-and-half mixture of white vinegar and seventy percent isopropyl alcohol works well. A couple of drops in each ear after getting the ears wet can be very effective at prevention. I also recommend directing a blow dryer on the LOW setting into the ear canal after bathing or swimming. Avoid dryers that are noisy to prevent hearing damage.

Dr. John Roberts is a Crawfordsville physician. His column is published Mondays in The Paper and he writes a daily health tip as well. Dr. Roberts is one of the owners of Sagamore News Media, which publishes The Paper of Montgomery County.