1. Acute diarrhea can be accompanied by nausea, loss of appetite, abdominal cramps, low-grade fever, and malaise (Table 44-2).

2. Symptoms begin as early as 8 to 12 hours after contaminated food or water has been ingested.

3. Dysentery (i.e., invasive disease) is present in 10% to 15% of cases, particularly associated with Shigella, C. jejuni, or Salmonella.

4. Dehydration (manifestations include tachycardia, orthostatic vital signs, dry mucous membranes, dark yellow urine and decreased urine output, lethargy, poor skin turgor) may be present and is most common in pediatric and geriatric populations.

5. Vomiting as the predominant symptom suggests food intoxication secondary to enterotoxin produced by Staphylococcus aureus, Bacillus cereus, or Clostridium perfringens, or gastroenteritis secondary to viruses, such as rotavirus in infants or norovirus in any age-group.

6. An abdominal examination of persons with TD often shows mild tenderness, but there should not be signs of peritonitis.

7. With persistent diarrhea (longer than 14 days’ duration), consider possible infection with intestinal parasites such as Giardia lamblia, Entamoeba histolytica, Cryptosporidium, Isospora, Cyclospora, or less common entities including the following:

1. TD typically runs a self-limited course of less than 1 week. Although recovery without antimicrobial treatment normally occurs in healthy adults, most travelers choose to avoid the inconvenience and discomfort of diarrhea by seeking medical treatment.

2. Severe, watery TD can cause life-threatening fluid loss. Treating serious dehydration is an urgent priority, especially in older persons, young children, and infants. Fluid replacement is the cornerstone of therapy.

3. To make an improvised ORS, one of the following methods can be used:

4. Fluids should be given at rates of 50 to 200 mL/kg/24 hr, depending on the patient’s hydration status.

5. Treatment with IV fluids is indicated for patients with severe dehydration and for those who cannot tolerate oral fluids.

6. Total food abstinence is unnecessary and not recommended. Patients should be encouraged to eat easily digested foods such as bananas, applesauce, rice, potatoes, noodles, crackers, toast, and soups. Dairy products should be avoided, because transient lactase deficiency can be caused by enteric infections. Caffeinated beverages and alcohol, which can enhance intestinal motility and secretions, should be avoided.

1. Antimotility drugs

2. Bismuth subsalicylate (BSS; Pepto-Bismol) reduces the number of stools passed in TD by approximately 16% to 18%. Although BSS is recommended for mild diarrhea, for moderate to severe disease, loperamide works better and with a faster onset of action.

3. Probiotics appear to reduce stool frequency and shorten the duration of acute infectious diarrhea by 1 day. The most extensively studied probiotics for diarrhea are Lactobacillus, Bifidobacterium, and Saccharomyces; however, optimal species and dosing have not been established. Potential mechanisms for their therapeutic action include protection of intestinal epithelial cells and barrier function, prevention of enterotoxin binding to intestinal epithelial cells, and regulation of intestinal microbial environment.

1. TD can be relieved in a little over 1 day after empiric antibiotic therapy is instituted. With the concurrent use of loperamide, relief is realized in a matter of hours. With reports of increasing resistance among enteric enteropathogens worldwide, trimethoprim/sulfamethoxazole can no longer be recommended. Until recently, one of the fluoroquinolones had been the drug of choice for empiric treatment of TD. With recognition that C. jejuni is a common cause of traveler’s diarrhea in Southeast Asia and that there is emerging resistance (up to 90%) to fluoroquinolones for Campylobacter in this region, the preferred agent for the empiric treatment of TD has become azithromycin for countries such as Thailand and India. Rifaximin, a nonabsorbed agent with broad activity against enteric pathogens, is effective in the treatment of TD in regions of the world where enterotoxigenic E. coli is the predominate pathogen. It is not recommended for treatment of bloody diarrhea or when an invasive pathogen is suspected, limiting its usefulness as a therapeutic agent in regions like Southeast Asia. However, because rifaximin can prevent diarrhea, including that caused by invasive pathogens, the most appropriate use of rifaximin might be as a chemoprophylactic agent. Recommended dosages of antimicrobial agents are shown in Table 44-4. Often a single dose suffices. Travelers who do not respond to empiric antibiotic treatment or who have persistent diarrhea of more than 1 week’s duration should seek medical attention. In the wilderness, Giardia can be an important cause of ongoing diarrhea unresponsive to antibiotics (see later).

2. Travelers with severe and incapacitating symptoms, or with dysentery, should be treated with empiric antimicrobial therapy immediately after the first passage of unformed stool.

3. Additional considerations follow:

1. Take dietary precautions. The risk for illness is lowest when a traveler’s meals are self-prepared in a private home, highest when food is obtained from street vendors, and intermediate when food is consumed at public restaurants. Unfortunately, many studies evaluating risk have found little correlation between routine precautions and illness. Dietary recommendations to decrease the potential for transmission of fecal pathogens through food and water are as follows:

2. Use of prophylactic medications to prevent TD

3. Antimicrobial prophylaxis for TD

1. Diarrhea that develops within 6 to 12 hours after a suspicious meal, most likely caused by ingesting a preformed toxin

2. A common source is often found to have affected multiple persons

3. Usually preceded by severe nausea and vomiting

4. Symptoms usually limited to 24 hours

5. Physical examination nonspecific

1. Treatment is directed toward fluid and electrolyte replacement (see earlier) and control of nausea.

2. No specific antibiotic therapy exists.

1. The severity of clinical manifestations is variable. In general, about half of exposed individuals clear the infection without clinical symptoms, and approximately 5% to 15% of individuals shed cysts asymptomatically

2. Average incubation period of 7 to 14 days (range 1 to 45 days)

3. Sometimes abrupt onset of explosive, watery diarrhea accompanied by abdominal cramps, foul flatus, vomiting, fever, and malaise; typically lasts 3 to 4 days before transition to subacute syndrome

4. Onset usually insidious, with symptoms that wax and wane

5. Stools becoming mushy and malodorous

6. Watery diarrhea alternating with soft stools and even constipation

7. Middle and upper abdominal cramping, substantial burning acid indigestion, sulfurous belching, nausea, bowel distention, early satiety, foul flatus

8. Dysenteric symptoms (blood and pus in the stool) are not features of giardiasis; fever and vomiting are infrequent except during initial onset.

9. May develop into a chronic process associated with malabsorption and weight loss

1. Treatment in the wilderness is usually initiated empirically based on the typical manifestations listed earlier.

2. Note that a cure can be achieved with one of several drugs. However, no drug is effective in all cases. In resistant cases, longer courses of two drugs taken concurrently may be effective.

3. Relapse may occur up to several weeks after treatment, which requires a second course of the same medication or an alternative drug.

4. Three antimicrobial drugs are currently recommended: tinidazole, metronidazole, and nitazoxanide.

5. Tinidazole (2000 mg adult dose; 50 mg/kg for children in a single dose) is highly effective and approved by the Food and Drug Administration (FDA) for treatment of giardiasis in persons older than 3 years. It should be taken with food. Tinidazole has a longer half-life than metronidazole and offers the advantage of a single-dose treatment. For those unable to swallow tablets, Tinidazole tablets may be compounded into an oral suspension.

6. Metronidazole can be used in children and adults (although giardiasis is not an FDA-approved indication for metronidazole). Adult dose is 250 mg tid for 5 to 7 days, and for children the dose is 15 mg/kg/day. Side effects are common and include nausea, gastrointestinal discomfort, and a metallic taste. Metronidazole may have a disulfiram-like effect, so alcohol consumption should be avoided.

7. Nitazoxanide, a nitrothiazolyl-salicylamide derivative, has been approved by the FDA for the treatment of giardiasis in children older than 1 year. In clinical trials it has been shown to be more effective than metronidazole in relieving symptoms in individuals with giardiasis. In addition, nitazoxanide is effective in treating multiple other infections caused by intestinal parasites (e.g., cryptosporidiosis and amebiasis). Nitazoxanide is available in liquid and tablet form but is expensive, and many pharmacies do not stock it. The recommended oral doses are as follows:

8. The nonabsorbable drug paromomycin (Humatin, 25 to 30 mg/kg in three divided doses for 5 to 10 days) has been effective and may be used during pregnancy. When considering treatment during pregnancy, when possible, withhold treatment until after discussing with an obstetrician because none of the treatment options is considered completely safe.

1. Most often, colonic inflammation without dysentery, causing lower abdominal cramping and altered stools

2. Weight loss, anorexia, nausea

3. Subacute infection developing into a nondysenteric bowel syndrome with symptoms of intermittent diarrhea, abdominal pain, weight loss, and flatulence

1. Dysentery developing suddenly or after a period of mild symptoms

2. Symptoms developing in as few as 8 to 10 days, but more often after weeks to months

3. Ill appearance, with frequent bloody stools, tenesmus, moderate to severe abdominal pain and tenderness, and fever (considerable variation in severity)

4. Rarely, significant fever

5. Complications in 1% to 4% of patients: bowel perforation, toxic megacolon, strictures, or an ameboma (inflammatory lesion containing trophozoites that develops in the colon)

6. Amoebic liver abscess acutely or years after infection

7. In the wilderness, diagnosis considered in any patient with dysentery who is not responding to an appropriate antibiotic

8. Asymptomatic cyst shedding and active gastrointestinal illness that persist for years if amebiasis is not treated

1. Invasive colitis is treated with metronidazole (alternative therapies include tinidazole or nitazoxanide), followed by a luminal agent (such as paromomycin, diiodohydroxyquin, or diloxanide furoate) to eliminate entraluminal cysts.

2. In general, treatment is effective for invasive infections but disappointing for luminal infections (no regimen is completely effective in eradicating intestinal infection).

1. Incubation period usually 7 to 10 days (range 3 to 28 days)

2. Syndrome generally mild and self-limited (typical duration of 5 to 6 days, range 2 to 26 days)

3. Asymptomatic infection may occur

4. Watery diarrhea (without blood or pus); abdominal cramps; nausea; flatulence; and, at times, vomiting and low-grade fever

5. Immunocompromised hosts experience more frequent and prolonged infections, with profuse chronic watery diarrhea, malabsorption, and weight loss lasting months to years.

6. Definitive diagnosis by stool examination or serologic techniques

1. Recovery from infection depends upon the immune status of the patient. Immunocompetent patients usually recover without treatment within 1 to 2 weeks while receiving supportive therapy for vomiting and dehydration.

2. When therapy is required, nitazoxanide is the preferred drug. The adult dose is 500 mg q12h for 3 days. Dosing for children is as follows:

1. The onset of diarrhea is usually abrupt.

2. Cyclospora causes a protracted watery diarrhea that can persist for weeks. Anorexia, nausea, and fatigue are common.

3. Definitive diagnosis is made by finding the microorganism in a stool sample treated with a modified acid-fast stain.

1. Cyclospora resists halogen-based (e.g., iodine and chlorine) water disinfection methods.

2. It is best killed by bringing drinking water to a boil.

3. The treatment of choice is trimethoprim/sulfamethoxazole; adult dose is one double-strength 160 mg/800 mg tablet PO q12h for 7 to 10 days. Ciprofloxacin 500 mg PO q12h for 7 days may be used as an alternative therapy for patients with a sulfa allergy.

1. Increase fluid intake (approximately 2 L of fluid daily in adults).

2. Patients should try to drink an extra glass of water for every glass of diuretic beverage (i.e., coffee, tea, or alcohol).

3. Increase dietary fiber.

4. Stool softeners such as docusate sodium (Colace 50 to 500 mg/day PO in one to four divided doses) enhance absorption of water and fat into stool, causing stool to soften. These drugs can be helpful, but they often lose their effectiveness over time.

5. At times a stronger stimulant medication may be indicated.

6. Bisacodyl (Dulcolax) is generally safe and effective.

7. Bisacodyl is also available as a rectal suppository. To use a rectal suppository, follow these steps:

8. Polyethylene glycol 3350 is available as MiraLax. The dose is one heaping teaspoon of this osmotic laxative in at least 236 mL (8 oz) of beverage once a day. It may require 2 to 4 days for the first bowel movement to occur. Because it can be habit forming, it should not be used consecutively for more than 2 weeks.