Gastrointestinal manifestations of the acquired immunodeficiency syndrome.

In addition to abnormalities in systemic immune function, patients with the acquired immunodeficiency syndrome (AIDS) and the pre-AIDS syndromes have significant abnormalities in the distribution of T-cell subsets in the intestinal tract. Such immune deficits predispose such patients to opportunistic infections and tumors, many of which involve the gastrointestinal tract. For example, Candida albicans often causes stomatitis and esophagitis. Intestinal infections with parasites (Cryptosporidium, Isospora belli, Microsporidia) or bacteria (Mycobacterium avium-intracellulare) are associated with severe diarrhea and malabsorption, whereas viruses like cytomegalovirus and herpes simplex virus cause mucosal ulcerations. Clinically debilitating chronic diarrhea develops in many AIDS patients for which no clear cause can be identified. Enteric pathogens like Salmonella and Campylobacter can be associated with bacteremias. Kaposi's sarcoma and lymphoma involving the intestinal tract are now well-recognized complications of AIDS. Although AIDS is not associated with a pathognomonic liver lesion, opportunistic infections and Kaposi's sarcoma or lymphoma may involve the liver.