Otitis media risk factors
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Hardik Patel, M.D.
Overview
Children below the age of seven years are much more prone to otitis media since the Eustachian tube is shorter and at more of a horizontal angle than in the adult ear. They also have not developed the same resistance to viruses and bacteria as adults. Numerous studies have correlated the incidence of acute otitis media in children with various factors such as nursing in infancy, bottle feeding when supine, parental smoking, diet, allergies and automobile emissions; but the most obvious weakness of such studies is the inability to control the variable of exposure to viral agents during the studies. One must also keep in mind that correlation does not establish causation. Breastfeeding for the first twelve months of life is associated with a reduction in the number and duration of all otitis media infections.[1]
Risk Factors
Risk factors for ear infections include the following:
- Attending daycare (especially those with more than 6 children)
- Changes in altitude or climate
- Cold climate
- Exposure to smoke
- Genetic factors (susceptibility to infection may run in families)
- Not being breastfed
- Pacifier use
- Recent ear infection
- Recent illness of any type (lowers resistance of the body to infection)
Infants and young children are especially susceptible to ear infections.
There are many reasons why children are more likely to suffer from otitis media than adults. First, children have more trouble fighting infections. This is because their immune systems are still developing. Another reason has to do with the child's eustachian tube. The eustachian tube is a small passageway that connects the upper part of the throat to the middle ear. It is shorter and straighter in the child than in the adult. It can contribute to otitis media in several ways.
The eustachian tube is usually closed but opens regularly to ventilate or replenish the air in the middle ear. This tube also equalizes middle ear air pressure in response to air pressure changes in the environment. However, a eustachian tube that is blocked by swelling of its lining or plugged with mucus from a cold or for some other reason cannot open to ventilate the middle ear. The lack of ventilation may allow fluid from the tissue that lines the middle ear to accumulate. If the eustachian tube remains plugged, the fluid cannot drain and begins to collect in the normally air-filled middle ear.
One more factor that makes children more susceptible to otitis media is that adenoids in children are larger than they are in adults. Adenoids are composed largely of cells (lymphocytes) that help fight infections. They are positioned in the back of the upper part of the throat near the eustachian tubes. Enlarged adenoids can, because of their size, interfere with the eustachian tube opening. In addition, adenoids may themselves become infected, and the infection may spread into the eustachian tubes.
Bacteria reach the middle ear through the lining or the passageway of the eustachian tube and can then produce infection, which causes swelling of the lining of the middle ear, blocking of the eustachian tube, and migration of white cells from the bloodstream to help fight the infection. In this process the white cells accumulate, often killing bacteria and dying themselves, leading to the formation of pus, a thick yellowish-white fluid in the middle ear. As the fluid increases, the child may have trouble hearing because the eardrum and middle ear bones are unable to move as freely as they should. As the infection worsens, many children also experience severe ear pain. Too much fluid in the ear can put pressure on the eardrum and eventually tear it.