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(Second of Two Parts)

The Pathophysiology of Diarrheal Diseases

Infectious Diarrheas

Enteric organisms cause diarrhea in several ways. Some are noninvasive but secrete toxins that interact with intestinal epithelial cells to stimulate fluid secretion (e.g., cholera). Others invade and destroy intestinal epithelial cells, thereby altering fluid transport. Selective destruction of small-intestinal villus cells by enteric viruses, for example, leaves the crypt portion of the epithelium unimpaired, so that its secretory activity is unopposed by the absorptive activity of villus cells.⁷⁹ Some enteric organisms are both enteroinvasive and toxicogenic (shigella,⁸⁰ for example). Others penetrate the epithelium, largely bypassing the enterocytes, and . . .