Chapter 122. Acute Infectious Diarrheal Diseases and Bacterial Food Poisoning (Part 5) History The answers to questions with high discriminating value can quickly narrow the range of potential causes of diarrhea and help determine whether treatment is needed. Important elements of the narrative history are detailed in Fig. 122-1. Physical Examination The examination of patients for signs of dehydration provides essential information about the severity of the diarrheal illness and the need for rapid therapy. Mild dehydration is indicated by thirst, dry mouth, decreased axillary sweat, decreased urine output, and slight weight loss. Signs of moderate dehydration include an orthostatic fall in blood pressure, skin tenting, and sunken eyes (or, in infants, a sunken fontanelle). Signs of severe dehydration range from hypotension and tachycardia to confusion and frank shock. Diagnostic Approach After the severity of illness is assessed, the clinician must distinguish between inflammatory and noninflammatory disease. Using the history and epidemiologic features of the case as guides, the clinician can then rapidly evaluate the need for further efforts to define a specific etiology and for therapeutic intervention. Examination of a stool sample may supplement the narrative history. Grossly bloody or mucoid stool suggests an inflammatory process. A test for fecal leukocytes (preparation of a thin smear of stool on a glass slide, addition of a drop of methylene blue, and examination of the wet mount) can suggest inflammatory disease in patients with diarrhea, although the predictive value of this test is still debated. A test for fecal lactoferrin, which is a marker of fecal leukocytes, is more sensitive and is available in latex agglutination and enzyme-linked immunosorbent assay formats. Causes of acute infectious diarrhea, categorized as inflammatory and noninflammatory, are listed in Table 122-1. Post-Diarrhea Complications Chronic complications may follow the resolution of an acute diarrheal episode. The clinician should inquire about prior diarrheal illness if the conditions listed in Table 122-2 are observed. Table 122-2 Post- Diarrhea Complications of Acute Infectious Diarrheal Illness Complication Comments Chronic diarrhea Lactase deficiency Occurs in ~1% of travelers with acute diarrhea Small- bowel bacterial overgrowth Malabsorption syndromes (tropical and celiac sprue) Protozoa account for ~⅓ of cases Initial presentation or exacerbation of inflammatory bowel disease May be precipitated by traveler's diarrhea Irritable bowel syndrome Occurs in ~10% of travelers with traveler's diarrhea Reiter's syndrome (reactive arthritis) Particularly likely after infection with invasive organisms (Shigella , Salmonella, Campylobacter) Hemolytic- uremic syndrome (hemolytic anemia, thrombocytopenia, and renal failure) Follows infection with Shiga toxin– producing bacteria (Shigella dysenteriae type 1 and enterohemorrhagic Escherichia coli) Epidemiology Travel History Of the several million people who travel from temperate industrialized countries to tropical regions of Asia, Africa, and Central and South America each year, 20–50% experience a sudden onset of abdominal cramps, anorexia, and watery diarrhea; thus traveler's diarrhea is the most common travel-related illness (Chap. 117). The time of onset is usually 3 days to 2 weeks after the traveler's arrival in a tropical area; most cases begin within the first 3–5 days. The illness is generally self-limited, lasting 1–5 days. The high rate of diarrhea among travelers to underdeveloped areas is related to the ingestion of contaminated food or water. The organisms that cause traveler's diarrhea vary considerably with location (Table 122-3). In all areas, enterotoxigenic and enteroaggregative E. coli are the most common isolates from persons with the classic secretory traveler's diarrhea syndrome. . Chapter 122. Acute Infectious Diarrheal Diseases and Bacterial Food Poisoning (Part 5) History The answers to questions with high discriminating. is more sensitive and is available in latex agglutination and enzyme-linked immunosorbent assay formats. Causes of acute infectious diarrhea, categorized as inflammatory and noninflammatory,. prior diarrheal illness if the conditions listed in Table 122- 2 are observed. Table 122- 2 Post- Diarrhea Complications of Acute Infectious Diarrheal Illness Complication Comments Chronic diarrhea