Chapter 117. Health Advice for International Travel (Part 4)

Prevention of Gastrointestinal Illness Diarrhea, the leading cause of illness in travelers (Chap. 122), is usually a short-lived, self-limited condition; however, 40% of affected individuals need to alter their scheduled activities, and another 20% are confined to bed. The most important determinant of risk is the destination. Incidence rates per 2-week stay have been reported to be as low as 8% in industrialized countries and as high as 55% in parts of Africa, Central and South America, and Southeast Asia. Infants and young adults are at particularly high risk. A recent review suggested that there is little correlation between...
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Chapter 117. Health Advice for International Travel (Part 4) Chapter 117. Health Advice for International Travel (Part 4) Prevention of Gastrointestinal Illness Diarrhea, the leading cause of illness in travelers (Chap. 122), is usually ashort-lived, self-limited condition; however, 40% of affected individuals need toalter their scheduled activities, and another 20% are confined to bed. The mostimportant determinant of risk is the destination. Incidence rates per 2-week stayhave been reported to be as low as 8% in industrialized countries and as high as55% in parts of Africa, Central and South America, and Southeast Asia. Infantsand young adults are at particularly high risk. A recent review suggested that thereis little correlation between dietary indiscretions and the occurrence of travelersdiarrhea. Earlier studies of U.S. students in Mexico showed that eating meals inrestaurants and cafeterias or consuming food from street vendors was associatedwith increased risk. Etiology (See also Table 122-3) The most frequently identified pathogens causingtravelers diarrhea are toxigenic Escherichia coli and enteroaggregative E. coli(Chap. 143), although in some parts of the world (notably northern Africa andSoutheast Asia) Campylobacter infections (Chap. 148) appear to predominate.Other common causative organisms include Salmonella (Chap. 146), Shigella(Chap. 147), rotavirus (Chap. 183), and norovirus (Chap. 183). The latter virus hascaused numerous outbreaks on cruise ships. Except for giardiasis (Chap. 208),parasitic infections are uncommon causes of travelers diarrhea. A growingproblem for travelers is the development of antibiotic resistance among manybacterial pathogens. Examples include strains of Campylobacter resistant toquinolones and strains of E. coli, Shigella, and Salmonella resistant totrimethoprim-sulfamethoxazole. Precautions Although the mainstay of prevention of travelers diarrhea involves foodand water precautions, the literature has repeatedly documented dietaryindiscretions by 98% of travelers within the first 72 h after arrival at theirdestination. The maxim Boil it, cook it, peel it, or forget it! is easy to rememberbut apparently difficult to follow. General food and water precautions includeeating foods piping hot; avoiding foods that are raw, poorly cooked, or sold bystreet vendors; and drinking only boiled or commercially bottled beverages,particularly those that are carbonated. Heating kills diarrhea-causing organisms,whereas freezing does not; therefore, ice cubes made from unpurified water shouldbe avoided. Self-Treatment (See also Table 122-5) As travelers diarrhea often occurs despite rigorousfood and water precautions, travelers should carry medications for self-treatment.An antibiotic is useful in reducing the frequency of bowel movements andduration of illness in moderate to severe diarrhea. The standard regimen is a 3-daycourse of a quinolone taken twice daily (or, in the case of some newerformulations, once daily). However, studies have shown that a single double doseof a quinolone may be equally effective. For diarrhea acquired in areas such asThailand, where >90% of Campylobacter infections are quinolone resistant,azithromycin may be a better alternative. Rifaximin, a poorly absorbed rifampinderivative, is highly effective against noninvasive bacterial pathogens such astoxigenic and enteroaggregative E. coli. The current approach to self-treatment of travelers diarrhea is for thetraveler to carry three once-daily doses of an antibiotic and to use as many dosesas necessary to resolve the illness. If neither high fever nor blood in the stoolaccompanies the diarrhea, loperamide may be taken in combination with theantibiotic. Prophylaxis Prophylaxis of travelers diarrhea with bismuth subsalicylate is widely usedbut only ~60% effective. For certain individuals (e.g., athletes, persons with arepeated history of travelers diarrhea, and persons with chronic diseases), a singledaily dose of a quinolone or azithromycin or a once-daily rifaximin regimenduring travel of When no infectious etiology can be identified, a trial of metronidazole therapy forpresumed giardiasis, a strict lactose-free diet for 1 week, or a several-week trial ofhigh-dose hydrophilic mucilloid (plus lactulose for persons with constipation)relieves the symptoms of many patients.