Although there are those lucky kids who sail through childhood never experiencing an ear infection, two-thirds of American children have at least one by the age of 2, and some children will even be plagued by recurring infections.
Causes of Ear Infections
There are two reasons children seem more vulnerable to ear infections than adults. First, ear infections are usually preceded by a cold (most common viral infections of the upper respiratory tract). Children, having lower immunity to viruses and many exposures, end up with plenty of colds. In fact, most children average six colds per year for the first few years of their lives.
The second reason children experience more ear infections than adults has to do with anatomy. The respiratory tract includes the structures of the nose, throat, sinuses, middle ears, and lungs. An infection that begins in one part of the respiratory tract can lead to the same, or more serious, infections in the other areas.
The structure that connects the middle ear space to the nose and throat is called the Eustacian tube. During a cold, the swelling and inflammation in the nose and throat prevent this tube from draining the normal fluid of the middle ear. As fluid backs up into the small middle ear space behind the ear drum, it can become infected by bacteria. In children, this tube is shorter, straighter, and more horizontal than in adults, making it easier for bacteria that normally live in the nose and throat to work itself backwards into the ear where it can create an infection.
Certain conditions increase the risk of ear infections. Any situation that makes a cold more likely also makes an ear infection more likely in susceptible children. Daycare attendance and households with many children increase the exposures to cold viruses.
Winter, when we live closer together and thus share germs more easily, is a common time to get colds and ear infections.
Genetics also play a role. The tendency to get ear infections runs in families, probably because we inherit certain shaped ears, just as we inherit the color of our eyes. Certain ethnic groups have a higher infection rate, notably, Native Americans and the Inuits of Alaska. Another risk factor is the habit of propping bottles or allowing children to drink from bottles while lying on their backs. This position can allow small amounts of milk to be sucked backwards into the middle ear space, which can then become infected. Fortunately, infants under 6 months are somewhat protected from cold viruses by antibodies passed on before birth, which means fewer colds and the ear infections that follow. Ear infections themselves are not contagious, though the preceding colds certainly are.