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Children with primary or acquired immunodeficiency are at increased risk for gastrointestinal (GI) infection or immune-related mucosal inflammation. The risk and severity of infection depends on the type of immunodeficiency; patients with deficiencies of antibody response are predisposed to extracellular bacterial infections and intestinal pathogens, and those with deficiencies of T cells are predisposed to both intracellular and extracellular infections. Patients with primary immunodeficiency are also more likely to develop autoimmune disorders, often affecting the GI tract. Conversely, those patients who present with various features of pediatric autoimmune enteropathy frequently can be found to have immunodeficiency disorders.
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GI disorders in children with immunodeficiency include opportunistic infections (viruses, bacteria, mycobacteria, fungi, or protozoa) and noninfectious inflammatory disorders (autoimmune and alloimmune). Subsequent dysmotility, malabsorption, or malnutrition can compound the morbidity of these GI problems. Additionally, medical treatments prescribed for children with immunodeficiency may result in adverse effects to the GI tract.
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OPPORTUNISTIC GI INFECTIONS
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The pandemic of human immunodeficiency virus (HIV) infection and acquired immunodeficiency syndrome (AIDS) has heightened our awareness of opportunistic infections, many which affect patients with both primary immunodeficiency and acquired immunosuppression. Efforts to limit the vertical transmission of HIV have reduced the incidence of HIV-related disease in children; however, pediatric HIV and AIDS remain important causes of immunodeficiency worldwide, particularly on the African continent. Opportunistic infections are listed in Table 386-1 according to the sites of GI involvement and are discussed in more detail in Chapter 231. In addition to those listed, immunodeficient patients also are at increased risk of disease from common bacterial and viral pathogens, as well as polymicrobial infections.
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Cytomegalovirus, rotavirus, adenovirus, and herpes simplex virus are the most common viral agents. Cytomegalovirus is commonly identified in children with immunodeficiency and can cause inflammation or ulceration throughout the GI tract, including the pancreatobiliary system. Symptoms may include diarrhea, dysphagia, vomiting, abdominal pain, and GI bleeding. Histologic identification of cytomegalovirus within the intestinal tissue is required to establish a pathogenic role because cytomegalovirus commonly is excreted in the urine or stool of asymptomatic individuals. While rarely an invasive pathogen in immunocompetent hosts, rotavirus may disseminate into the liver parenchyma of immunocompromised children. Adenovirus is reported to cause colitis in adults with AIDS and fulminant hepatitis in immunocompromised children. Diagnosis of adenovirus infection depends on histologic identification, which should be confirmed by culture. Herpes simplex virus usually causes oral and esophageal lesions and produces symptoms of dysphagia and odynophagia. ...