Diarrheal Disease in the immunocompromised Host
The digestive tract is in direct communication with the environment. It is a first line of defense against harmful agents that may enter the systemic circulation and cause disease of an infectious, allergic, or autoimmune nature. An elaborate defense system acts either at the mucosal surface or within the lumen of the intestine, nonimmunologically (pH, mucus, secretions, microflora, etc) and immunologically (IgG, T cells, polymorphonuclear leukocytes, eosinophils). Any disturbance of these host defenses, acquired or congenital, may result in increased host susceptibility to infection.
Patients with primary immunodeficiency have frequent illnesses of the gastrointestinal tract. The increased susceptibility results from (1) change in gastric pH: achlorhydria decreases the efficiency of the gastric barrier, allows for the proliferation of organisms in the small intestine, and permits infections by Escherichia coli, Shigella, Salmonella, and Vibrio organisms;
