The acquired immunodeficiency syndrome (AIDS) has been reported in children since 1983 and may be found among hemophiliacs, transfusion recipients, infants born to high-risk parents, and adolescents. The gastrointestinal (GI) manifestations observed in patients with AIDS include esophagitis and diarrhea with or without parasitic, viral, or bacterial infections. Nutrient malabsorption is not always a factor in the illness, although children may have nutrient malabsorption even if they do not have overt symptoms. Esophagitis caused by Candida albicans can be the presenting symptom in patients with AIDS and may or may not be associated with oral thrush.

Organisms commonly associated with the diarrhea that occurs in patients with AIDS are C. albicans, Cryptosporidium, cytomegalovirus, atypical mycobacteria, and Salmonella typhimurium. Even in the absence of systemic or enteric infections or malignancy, many adult and pediatric patients with AIDS suffer from chronic diarrhea, anorexia, and weight loss. Mycobacterium avium-intracellulare has been found in the small bowel of patients with AIDS and has been associated with diarrhea. The organism is an acid-fast bacillus that has been found in macrophages of the lamina propria of the small bowel. Patients with cytomegalovirus infections may have diarrhea, and viral inclusions can be found at different levels of the GI tract. Ileitis or colitis, together with esophageal and colonic ulcers from which the virus can be cultured, has been reported.

The GI symptoms of AIDS can mimic those of other diseases. The symptoms of patients with AIDS who suffer from chronic diarrhea and have marked abdominal distention and malnutrition have been compared with the symptoms of celiac disease. The histologic picture of the small-bowel mucosa is compatible with partially treated celiac disease in that it has patchy atrophy alternating with more normal segments of mucosa. In other patients, the clinical symptoms are similar to those of inflammatory bowel disease. These patients complain of abdominal pain, weight loss, diarrhea, and fever. AIDS in children may manifest also as pseudomembranous necrotizing jejunitis.

AIDS may be expressed as a failure to thrive, with or without diarrhea. Diarrhea and malabsorption are more prevalent occurrences in patients with documented GI infections. Frequently, increased fecal fat, diminished appetite, and weight loss are observed in these patients. A small-bowel biopsy can identify infiltration of the lamina propria with chronic inflammatory cells and occasional subtle villous atrophy. Nonspecific inflammatory cell infiltrate also can be seen in the colon. These histologic and functional abnormalities have been called AIDS enteropathy. The evaluation of patients who have AIDS and present with GI symptoms should include a careful search for bowel pathogens. However, in many patients in whom pathogens can be identified, often diarrhea persists despite a variety of therapeutic interventions, including systemic treatment for fungal or mycobacterial disease and the intravenous administration of antibiotics for other infections. Feedings can be administered through a nasogastric tube if affected children are too debilitated to take food orally. This technique also may facilitate gastric emptying and tolerance of formula.