Traveler’s Diarrhea JOHNNIE YATES, M.D., CIWEC Clinic Travel Medicine Center, Kathmandu, Nepal Acute diarrhea affects millions of persons who travel to developing countries each year. Food and water contaminated with fecal matter are the main sources of infection. Bacteria such as enterotoxigenic Escherichia coli, enteroaggregative E. coli, Campylobacter, Salmonella, and Shigella are common causes of traveler’s diarrhea. Parasites and viruses are less common etiologies. Travel destination is the most significant risk factor for traveler’s diarrhea. The efficacy of pretravel counseling and dietary precautions in reducing the incidence of diarrhea is unproven. Empiric treatment of traveler’s diarrhea with antibiotics and loperamide is effective and often limits symptoms to one day. Rifaximin, a recently approved antibiotic, can be used for the treatment of traveler’s diarrhea in regions where noninvasive E. coli is the predominant pathogen. In areas where invasive organisms such as Campylobacter and Shigella are common, fluoroquinolones remain the drug of choice. Azithromycin is recommended in areas with qui- nolone-resistant Campylobacter and for the treatment of children and pregnant women. (Am Fam Physician 2005;71:2095-100, 2107-8. Copyright© 2005 American Academy of Family Physicians.) ILLUSTRATION BY SCOTT BODELL ▲ Patient Information: cute diarrhea is the most com- mised and those with lowered gastric acidity A handout on traveler’s mon illness among travelers. Up (e.g., patients taking histamine H block- diarrhea, written by the 2 author of this article, is to 55 percent of persons who ers or proton pump inhibitors) are more provided on page 2107. travel from developed countries susceptible to traveler’s diarrhea. Recently, toA developing countries are affected.1,2 A a genetic susceptibility has been demon- See page 2029 for 3 5 strength-of-recommen- study of Americans visiting developing strated. Younger age and adventurous travel dation labels. countries found that 46 percent acquired increase the risk of developing traveler’s diarrhea. The classic definition of traveler’s diarrhea,3,6 but persons staying at luxury diarrhea is three or more unformed stools resorts or on cruise ships also are at risk.7,8 in 24 hours with at least one of the following Food and water contaminated with fecal symptoms: fever, nausea, vomiting, abdomi- matter are the main reservoirs for the patho- nal cramps, tenesmus, or bloody stools. gens that cause traveler’s diarrhea. Unsafe Milder forms can present with fewer than foods and beverages include salads, unpeeled three stools (e.g., an abrupt bout of watery fruits, raw or poorly cooked meats and sea- diarrhea with abdominal cramps). Most food, unpasteurized dairy products, and tap cases occur within the first two weeks of water. Eating in restaurants increases the travel and last about four days without treat- probability of contracting traveler’s diar- ment.1,3 Although traveler’s diarrhea rarely rhea6 and food from street vendors is par- is life threatening, it can result in significant ticularly risky.9,10 Cold sauces, salsas, and morbidity; one in five travelers with diar- foods that are cooked and then reheated also rhea is bedridden for a day and more than are risky.6,11 one third have to alter their activities.1,3 In contrast to the largely viral etiology of Destination is the most significant risk gastroenteritis in the United States, diarrhea factor for developing traveler’s diarrhea.1-4 acquired in developing countries is caused Regions with the highest risk are Africa, mainly by bacteria1,4,6,12 (Table 1). Entero- South Asia, Latin America, and the Middle toxigenic Escherichia coli is the pathogen East. Travelers who are immunocompro- most frequently isolated, but other types of June 1, 2005 ◆ Volume 71, Number 11 www.aafp.org/afp American Family Physician 2095 Downloaded from the American Family Physician Web site at www.aafp.org/afp. Copyright© 2005 American Academy of Family Physicians. For the private, noncommercial use of one individual user of the Web site. All other rights reserved. Contact [email protected] for copyright questions and/or permission requests. Strength of Recommendations Key clinical recommendation Label References Antibiotics (usually a quinolone) A 28 24 hours.18 Seafood ingestion syndromes such as diar- should be used to reduce the duration and severity of traveler’s rhetic shellfish poisoning, ciguatera poisoning, and diarrhea. scombroid poisoning also can cause diarrhea in travel- Loperamide (Imodium) can be used A 38, 39 ers. These syndromes can be distinguished from trav- with antibiotics for most adults eler’s diarrhea by symptoms such as perioral numbness with traveler’s diarrhea. and reversal of temperature sensation (ciguatera poison- Travelers may be advised to avoid B 3, 20, 21 ing) or flushing and warmth (scombroid poisoning).19 high-risk foods and eating behaviors. Prevention Antibiotic prophylaxis should not be C 9, 23 used routinely in persons at risk of Although travelers often are advised to “Boil it, cook it, developing traveler’s diarrhea. peel it, or forget it,” data on the effectiveness of dietary precautions in preventing traveler’s diarrhea are incon- A = consistent, good-quality patient-oriented evidence; B = incon- clusive.3,6,20 Many travelers find it difficult to adhere to sistent or limited-quality patient-oriented evidence; C = consensus, dietary recommendations.21 In a study3 of American disease-oriented evidence, usual practice, opinion, or case series. See page 2029 for more information. travelers, nearly one half developed diarrhea despite pre- travel advice on avoidance measures; even persons who strictly followed dietary recommendations developed E. coli such as enteroaggregative E. coli have been recog- diarrhea. Avoiding high-risk foods and adventuresome nized as common causes of traveler’s diarrhea.13 Invasive eating behaviors may reduce the inoculum of ingested pathogens such as Campylobacter, Shigella, and non- pathogens or prevent the development of other enteric typhoid Salmonella are relatively common depending diseases such as typhoid and hepatitis A and E. on the region, while Aeromonas and non-cholera Vibrio Boiling is the best way to purify water. Iodination or species are encountered less frequently. chlorination is acceptable but does not kill Cryptospo- Protozoal parasites such as Giardia lamblia, Ent- ridium or Cyclospora, and increased contact time is amoeba histolytica, and Cyclospora cayetanensis are required to kill Giardia in cold or turbid water.22 Filters uncommon causes of traveler’s diarrhea, but increase with iodine resins generally are effective in purifying in importance when diarrhea lasts for more than two weeks.14 Parasites are diagnosed more frequently in returning travelers because of longer incubation periods TABLE 1 (often one to two weeks) and because bacterial patho- Common Causes of Traveler’s Diarrhea gens may have been treated with antibiotics. Rotavirus and noroviruses are infrequent causes of traveler’s diar- Bacteria rhea, although noroviruses have been responsible for Enterotoxigenic Escherichia coli outbreaks on cruise ships. Other E. coli types (e.g., enteroaggregative E. coli) The prevalence of specific organisms varies with travel Campylobacter destination.1,4,12,13,15 Available data suggest that E. coli is Salmonella (non-typhoid) the predominant cause of traveler’s diarrhea in Latin Shigella America, the Caribbean, and Africa, while invasive Aeromonas pathogens are relatively uncommon. Enterotoxigenic Vibrio (non-cholera) E. coli and enteroaggregative E. coli may be responsible Parasites for up to 71 percent of cases of traveler’s diarrhea in Giardia lamblia Mexico.13 In contrast, Campylobacter is a leading cause Entamoeba histolytica of traveler’s diarrhea in Thailand15-17 and also is common Cyclospora cayetanensis in Nepal.6 Regional variation also exists with parasitic Cryptosporidium parvum causes of traveler’s diarrhea (Table 2).12,13 For example, Viruses Cyclospora is endemic in Nepal, Peru, and Haiti. Rotavirus Food poisoning is part of the differential diagnosis Noroviruses of traveler’s diarrhea. Gastroenteritis from preformed NOTE: Organisms in each category are sorted by the most common toxins (e.g., Staphylococcus aureus, Bacillus cereus) is causes; however, the prevalence of specific pathogens may vary sig- characterized by a short incubation period (one to nificantly based on travel destination. six hours), and symptoms typically resolve within 2096 American Family Physician www.aafp.org/afp Volume 71, Number 11 ◆ June 1, 2005 Traveler’s Diarrhea ers who are at high risk of developing traveler’s diarrhea TABLE 2 and related complications (e.g., immunocompromised Isolation Rates of Enteric Pathogens Among persons). Prophylaxis with fluoroquinolones is up to Travelers with Diarrhea in Three Regions 90 percent effective.23 Rifaximin (Xifaxan) may prove to be the preferred antibiotic because it is not absorbed Kenya India Jamaica and is well tolerated, although data on its effectiveness Pathogen (%) (%) (%) for prophylaxis have not yet been published. Enterotoxigenic 35 24 to 25 12 to 30 Bismuth subsalicylate (Pepto-Bismol) provides a rate Escherichia coli of protection of about 60 percent against traveler’s diar- Enteroaggregative NR 19 26 rhea.24 However, it is not recommended for persons tak- E. coli ing anticoagulants or other salicylates. Because bismuth Campylobacter 5 3 5 subsalicylate interferes with the absorption of doxycy- Shigella 9 10 0.3