Ear Infections - Causes

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Causes of Otitis Media with Effusion (OME)

OME may occur spontaneously following an episode of acute otitis media. Susceptibility to OME may also be due to an abnormal or malfunctioning Eustachian tube that causes a negative pressure in the middle ear, which allows fluid to leak in through capillaries. Problems in the Eustachian tube can be due to viral infections, second-hand smoke, injury, birth defects (such as cleft palate), or genetic diseases that affect the defense systems, such as Kartagener's syndrome.

The Incidence of Ear Infections and Other Airway Problems

Increased diagnosis of other disorders and infections of the upper and lower airways, such as asthma, allergies, and sinusitis, have paralleled the rise in ear infections. For example, the same bacteria are often responsible for both ear infections and sinusitis. In one study, 38% of children with ear infections also had sinusitis, and other studies have reported that nearly half of children with OME have concurrent sinusitis. While these studies may have overestimated the extent of clinically important sinus disease, the association is significant, even if the causal relationships are unclear. Researchers are looking for common risk factors, such as:

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• Increase in Day Care Center Attendance. Although ear infections themselves are not contagious, the respiratory infections that precipitate them can pose a risk for children with close and frequent exposure to other children. Some experts believe that the increase in ear and other infections may be due to the higher attendance of very small children, including infants, in day care centers beginning in the 1970s. For children who had the condition for a long time, however, neither day care attendance nor any other risk factor, including a history of upper respiratory tract infections or family history of OME, appeared to be relevant. Attendance in day care centers, then, may explain part, but not all, of the current increase in ear infections and other upper airway disorders.
• Increase in Allergies. Some experts believe that an increase in allergies is also partially responsible for the higher number of ear infections, which is unlikely to be related to day care attendance. Studies indicate that 40 - 50% of children over 3 years old who have chronic otitis media also have allergic rhinitis (hay fever). Allergies are also associated with asthma and sinusitis.

Review Date: 03/02/2006
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

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