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Category: Viruses and Viral Pathogenesis
Respiratory Infections, Page 1 of 2
< Previous page | Next page > /docserver/preview/fulltext/10.1128/9781555819439/9781555819422.ch2-1.gif /docserver/preview/fulltext/10.1128/9781555819439/9781555819422.ch2-2.gifAbstract:
Respiratory viral infections have a major impact on health. Acute respiratory illnesses, largely caused by viruses, are the most common illness experienced by otherwise healthy adults and children. Data from the United States, collected in the 1992 National Health Interview Survey, suggest that such illnesses are experienced at a rate of 85.6 illnesses per 100 persons per year and account for 54% of all acute conditions exclusive of injuries (1). A total of 44% of these illnesses require medical attention and result in 287 days of restricted activity, 94.4 days lost from work, and 182 days lost from school per 100 persons per year. The morbidity of acute respiratory disease in the family setting is significant. The Tecumseh study, a family-based surveillance study of respiratory illness, estimated that approximately one-quarter of respiratory illnesses result in consultation with a physician (2). Illness rates for all acute respiratory conditions are highest in young children, and children below the age of 9 have been estimated to experience between five and nine respiratory illnesses per year (3).
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Many of the viruses that affect the respiratory tract exhibit a seasonal variation in prevalence. In this figure, numbers of virus isolates from children seen in private pediatric practices in Rochester, NY, are plotted by month of isolation. Data represent the 6-year average from 1990 to 1995 and are expressed as the percentage of all isolates of that virus that occurred in the given month.
Many of the viruses that affect the respiratory tract exhibit a seasonal variation in prevalence. In this figure, numbers of virus isolates from children seen in private pediatric practices in Rochester, NY, are plotted by month of isolation. Data represent the 6-year average from 1990 to 1995 and are expressed as the percentage of all isolates of that virus that occurred in the given month.
Posteroanterior roentgenogram of the neck of a child with viral croup that shows the characteristic narrowing of the air shadow of the trachea in the subglottic area. (Courtesy of Dr. Carolyn B. Hall, University of Rochester)
Posteroanterior roentgenogram of the neck of a child with viral croup that shows the characteristic narrowing of the air shadow of the trachea in the subglottic area. (Courtesy of Dr. Carolyn B. Hall, University of Rochester)
Lateral neck films of the neck in a child with epiglottitis demonstrates the characteristic thickening of the epiglottis in this disease and may be helpful in distinguishing this illness from croup or retropharyngeal abscess. (Courtesy of Dr. Caren B. Hall, University of Rochester)
Lateral neck films of the neck in a child with epiglottitis demonstrates the characteristic thickening of the epiglottis in this disease and may be helpful in distinguishing this illness from croup or retropharyngeal abscess. (Courtesy of Dr. Caren B. Hall, University of Rochester)
Pathophysiology of croup. Both mechanical obstruction of airflow and ventilation-perfusion mismatching due to parenchymal infection of the lung are responsible for the hypoxia and respiratory distress of croup. (Modified from Hall, Reference 206 , with permission)
Pathophysiology of croup. Both mechanical obstruction of airflow and ventilation-perfusion mismatching due to parenchymal infection of the lung are responsible for the hypoxia and respiratory distress of croup. (Modified from Hall, Reference 206 , with permission)
The CXR in bronchiolitis characteristically shows hyperinflation due to obstruction to airflow. A variety of other findings may be present, including interstitial infiltrates or lobar consolidation. (Courtesy of Dr. Caren B. Hall, University of Rochester)
The CXR in bronchiolitis characteristically shows hyperinflation due to obstruction to airflow. A variety of other findings may be present, including interstitial infiltrates or lobar consolidation. (Courtesy of Dr. Caren B. Hall, University of Rochester)
Pathophysiology of bronchiolitis. Viral infection of the lower respiratory tract results in inflammation and increased mucus production. Both airway obstruction and ventilation-perfusion mismatching are responsible for the clinical findings of hypoxia, hyperinflation, and hypoventilation. If uncorrected, these defects can lead to apnea or sudden death. (Modified from Wohl and Chernick, Reference 71 , with permission)
Pathophysiology of bronchiolitis. Viral infection of the lower respiratory tract results in inflammation and increased mucus production. Both airway obstruction and ventilation-perfusion mismatching are responsible for the clinical findings of hypoxia, hyperinflation, and hypoventilation. If uncorrected, these defects can lead to apnea or sudden death. (Modified from Wohl and Chernick, Reference 71 , with permission)