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Many children are evaluated by their physicians because of recurrent infections, a relatively common complaint in early childhood. These children are considered to have an increased susceptibility to infections as compared with children of similar age. Both extrinsic and host factors can increase the risk of developing infections, and may be found in most such cases (Table 183-1). Identification and management of these underlying conditions would result in a reduction in frequency of infectons. Examples of extrinsic factors include human immunodeficiency virus infection, use of immunosuppressor drugs, high exposure to infectious agents in a daycare setting, presence of foreign bodies, or exposure to parental smoking. Host factors that increase risks of developing infections include genetic deficiencies of the immune response and several other conditions: respiratory allergies, abnormal anatomy, and diseases affecting barriers or epithelia such as cystic fibrosis.
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ASSESSMENT OF THE CHILD WITH INCREASED SUSCEPTIBILITY TO INFECTIONS
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As with other clinical conditions, a detailed history is most helpful to obtain clues and to suggest laboratory testing leading to specific diagnosis. The threshold to define high frequency of infections might not be the same for every child because of additional considerations of external factors as mentioned above. However, guidelines have been suggested: 2 or more systemic bacterial infections at any time (such as sepsis, deep-seated abscesses, or meningitis), 3 or more bacterial infections, or 6 to 8 or more upper respiratory tract infections in 1 year.
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Respiratory tract infections are common in children. Two examples of host factors favoring infections are allergy conditions and cystic fibrosis. Allergic disease should be investigated because of its increasing prevalence and its role in causing respiratory airway and skin inflammation. Supporting evidence may come from family history of allergic diseases, frequent itching and sneezing, and findings on physical exam of allergic signs such as allergic shiners, clear nasal discharge, eczema, or wheezing. Diagnostic tests include allergen skin testing and serum IgE levels. Patients with cystic fibrosis are particularly susceptible to respiratory infections with Pseudomonas aeruginosa, Burkholderia species, and Staphylococcus aureus. Cystic fibrosis usually is confirmed with a sweat chloride test.
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A high frequency of infections, their severity, or the nature of the infectious organism should prompt an evaluation for deficiencies of the immune response. Hospitalization or surgical intervention (eg, abscess drainage) for infections, prolonged antibiotic courses, and shortened intervals between infectious episodes are indicators of an unusual severity of infections. Other significant history associated with immunodeficiencies include weight loss, failure to ...