Travelers' Diarrhea

Travelers' diarrhea is the most common travel-related infection. It may be caused by many different organisms, including bacteria such as E. coli, Salmonella, Shigella, Campylobacter, Aeromonas, Plesiomonas, and vibrios; parasites such as Giardia, Entamoeba histolytica, Cryptosporidium, and Cyclospora; and viruses. In addition to diarrhea, symptoms may include nausea, vomiting, abdominal pain, fever, sweats, chills, headache, and malaise. The chief complication is dehydration, which may become severe, especially in warmer climes.

The best means of prevention is to avoid any questionable foods or beverages. Do not drink tap water unless it has been boiled, filtered, or chemically disinfected. Do not drink unbottled beverages or drinks with ice. Do not eat fruits or vegetables unless they have been peeled or cooked. Avoid cooked foods that are no longer piping hot. Cooked foods that have been left at room temperature are particularly hazardous. Avoid unpasteurized milk and any products that might have been made from unpasteurized milk, such as ice cream. Avoid food and beverages obtained from street vendors. Do not eat raw or undercooked meat or fish, including ceviche. Some types of fish may contain poisonous biotoxins even when cooked. Barracuda in particular should never be eaten. Other fish that may contain toxins include red snapper, grouper, amberjack, sea bass, and a large number of tropical reef fish.

Although antibiotics may be taken prophylactically to prevent travelers' diarrhea (i.e. taken on a daily basis before symptoms have a chance to occur), this isn't generally recommended because starting antibiotics after diarrhea begins works well and because increased antibiotic use might lead to a greater incidence of side-effects and the selection of resistant organisms. Prophylactic antibiotics might be appropriate for situations in which diarrhea might prove unusually troublesome (i.e. business trip, diplomatic mission, athletic event) or for travelers who are immunocompromised or who have a history of intestinal disorders, such as those with inflammatory bowel disease. Appropriate regimens include ciprofloxacin (Cipro)(PDF) or levofloxacin (Levaquin)(PDF) 500 mg once daily or (less effectively) trimethoprim-sulfamethoxazole (Bactrim; Septra) one double-strength tablet daily. Bismuth subsalicylate (Pepto-Bismol) (two tablets or two ounces four times daily) will reduce the likelihood of travelers' diarrhea, but few take this because it is inconvenient. Side-effects may include black tongue, black stools, nausea, constipation, and ringing in the ears (tinnitus). Bismuth subsalicylate should not be taken by those with aspirin allergy, kidney disease, or gout, and should not be taken for more than three weeks. Quinolone antibiotics may bind to metallic cations such as bismuth; they should not be taken concurrently.

The standard recommendation is for travelers at risk to bring along an antibiotic and an antidiarrheal drug to be started promptly if significant diarrhea occurs, defined as three or more loose stools in an 8-hour period or five or more loose stools in a 24-hour period, especially if associated with nausea, vomiting, cramps, fever or blood in the stool. A quinolone antibiotic is usually prescribed: either ciprofloxacin (Cipro)(PDF) 500 mg twice daily or levofloxacin (Levaquin)(PDF) 500 mg once daily for a total of three days. Quinolones should not be given to children, pregnant women, or anyone with a history of quinolone allergy. Alternative regimens include a three day course of rifaximin (Xifaxan) 200 mg three times daily or azithromycin (Zithromax) 500 mg once daily. Rifaximin should not be used by those with fever or bloody stools and is not approved for pregnant women or those under age 12. Azithromycin should be avoided in those allergic to erythromycin or related antibiotics. For children, the dosage of azithromycin is 10 mg/kg on day 1, up to 500 mg, and 5 mg/kg on days 2 and 3, up to 250 mg. Another option is trimethoprim/sulfamethoxazole (Bactrim), which is used less often today because of increasing bacterial resistance but may be appropriate for children or those unable to tolerate other antibiotics. The dosage is one double-strenth tablet twice daily for adults and 5 mg/kg trimethoprim/25 mg/kg sulfa twice daily for children. Trimethoprim-sulfamethoxazole should not be given to pregnant women or those with a history of sulfa allergy. An antidiarrheal drug such as loperamide (Imodium) or diphenoxylate (Lomotil) should be taken as needed to slow the frequency of stools, but not enough to stop the bowel movements completely. Diphenoxylate (Lomotil) and loperamide (Imodium) should not be given to children under age two.

Most cases of travelers' diarrhea are mild and do not require either antibiotics or antidiarrheal drugs.

Adequate fluid intake is essential. Oral rehydration solutions, which are rich in salt and sugar, are widely available and highly effective. If fluids that do not contain salt are used, plain salted foods, such as crackers, are recommended. Dairy products should be avoided until diarrhea has subsided, as these are often difficult to digest while the intestine is inflamed.

If diarrhea is severe or bloody, or if fever occurs with shaking chills, or if abdominal pain becomes marked or if diarrhea persists for more than 72 hours, medical attention should be obtained, if possible.

From the World Health Organization (WHO)

Enterohaemorrhagic Escherichia coli (EHEC)

Guide on Safe Food for Travelers

From the Centers for Disease Control (CDC)

Travelers' Diarrhea (Yellow Book)

Travelers' Diarrhea: frequently asked questions

From "Health Information for Overseas Travel" (U.K.)

Prevention of travellers' diarrhoea and other food and water-borne diseases