Inflammation of the middle ear cavity, a condition known as otitis media, is the most common reason besides regular checkups for taking a child to the doctor, accounting for more than 31 million visits to doctors a year.
An ongoing study by Gunnar B. Stickler, emeritus professor of pediatrics at the Mayo Clinic and Mayo Medical School in Rochester, Minn., has found that ear infections are parents' No. 1 health concern.
The National Center for Health Statistics says there were 15.4 million episodes of acute ear infections in children in 1988, 10 million of them in youngsters under age 5.
Health experts estimate an average of about $90 is spent for the treatment of just one episode of ear infection, for a total of more than $2 billion annually for physicians' fees, antibiotics and surgery for inserting ear tubes.
Although anecdotal information shared by parents and doctors certainly seems to support the notion that ear infections are more common than they used to be, there is no epidemiologic data to show whether that is the case, researchers say.
However, children today are more likely to be in places such as day-care centers and nursery schools where they are exposed to viruses and bacteria. If a toddler suffering from a cold puts a toy in his mouth and that toy is then handled or chewed on by another youngster, infection can spread.
"Certainly we know that day care is a factor, because you mix children who bring organisms from different households together," said Jerome O. Klein, pediatrics professor at Boston University School of Medicine. "At a young age, children are very social and they mix organisms easily."
Some studies have shown that children in day-care centers are more apt to suffer from persistent ear infections. But regardless of where a child is cared for, it is the rare youngster who doesn't get an ear infection.
Studies have shown that boys are at greater risk for ear infections than girls, as are children whose siblings have a history of ear infections or who live in a house where someone smokes.
The middle ear can become infected when bacteria from the back of the nose spread by way of the eustachian tube. Fluid and pus caused by the inflammation can build up behind the eardrum and put pressure on it if the eustachian tube does not properly do its job of draining the fluid from the middle ear.
The pressure of the fluid on the eardrum causes pain -- something a child may react to by crying or being fussy or waking in the middle of the night. An ear infection may also be accompanied by a noticeable fever.
Because ear infections often are complications resulting from a cold, sore throat or other respiratory infection, most cases happen during the usual cold season, from late fall to spring. Some doctors say, however, that they now are seeing a significant number of ear infections in summer months as well.
A 10-day course of antibiotics is the standard treatment for an ear infection. Amoxicillin, a penicillin-type antibiotic, is the drug of choice for most infections, but studies are showing that the major strains of bacteria responsible for ear infections are becoming increasingly resistant to the drug.
Although the level of resistance varies from one part of the country to another, studies in Dallas have found that 25 percent to 30 percent of the bacteria responsible for ear infections are resistant to amoxicillin, said George McCracken, the Pediatric Infectious Disease Journal editor.
When an infection is not cleared by amoxicillin, which costs up to $8 depending on the prescribed dose, doctors must turn to expensive alternatives. For instance, one drug, Ceclor, costs about $26 to treat a 3-year-old for two weeks. Another drug, Pediazole, costs about $23 for the same child.
Even after an infection clears, fluid, which is often more of a gummy consistency, can remain in the middle ear for months, resulting in slight-to-moderate hearing loss. Doctors say young children who have fluid in their middle ear for months at a time may suffer delays in speech development because they are not hearing well.
In cases where a child suffers from one ear infection after another -- even when taking a daily low dose of antibiotics to ward off infection -- or when the fluid persists in the middle ear for months, a doctor may recommend that tubes be placed in the child's ears.
Studies vary on the effectiveness of the tubes. And some physicians, including Dr. Stickler of the Mayo Clinic, believe there is no evidence to show the tubes do any good, and that they may in fact cause permanent damage to the eardrum.
It is estimated that anywhere from 500,000 to 1 million sets of ear tubes are placed in children each year in this country. The procedure costs up to $2,000.
Max Ronis, professor and chairman of the department of otorhinolaryngology and chief of the ear, nose and throat section at St. Christopher's Hospital for Children in Philadelphia, said tubes should be considered only after "careful medical treatment" fails to clear up a child's problem.
During a surgical procedure lasting about 20 minutes, the doctor drains any fluid and pus from the middle ear and inserts a tiny tube -- called a tympanostomy tube -- into each of the eardrums. The tube creates a small opening into the middle ear and acts to aerate the cavity.
A child is placed under general anesthesia for the insertion. Because the tubes typically fall out after six months to one year, a child may undergo the procedure more than once. Most children outgrow ear infections by the time they reach grade school because their eustachian tubes have grown and function better.