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Canada Communicable Disease Report
An Advisory Committee Statement (ACS) PERSISTENT DIARRHEA IN THE RETURNED TRAVELLERIntroductionDiarrhea is the most common affliction of travellers to developing countries(1) occurring in 20% to 50% of those travelling to destinations in tropical and subtropical areas of Latin America, Africa, and southern Asia(2,3). Even within the developed world, severe or temporary sewage-system failures or flooding may contaminate water supplies, and diarrheal illness may result(4,5). Travellers' diarrhea (TD) is usually an acute illness characterized by at least three loose or semiformed stools per day. It may be associated with other symptoms such as nausea, vomiting, and abdominal pain(6). The onset of illness usually coincides with travel, although it may occur during the first 7 to 10 days after returning home. The prevention and treatment of acute, usually self-limiting, TD can be found in the CATMAT statement on TD(7). In general, no investigations are necessary and self-treatment can be advocated for acute TD unless the patient is very ill, has a significant underlying medical illness, is immunodeficient, or has bloody stools; if any of these apply, medical assistance should be sought for investigation and management. Some travellers may not have onset of their symptoms until after returning from travel. This may be acute TD with a prolonged incubation period, i.e. onset > 7 days after leaving a tropical location. In such cases diarrhea is less likely to be due to bacterial agents. Campylobacter may have an incubation period of up to 10 days; however, the illness which begins after return is more likely to be due to other etiologies with longer incubation periods such as giardiasis (3 to 25 days), amoebiasis (2 to 4 weeks), and schistosomiasis (2 to 6 weeks). As well, the gastrointestinal illness may be unrelated to and only coincident with the recent travel. These individuals should be evaluated by a health-care worker and investigated to determine the etiology as outlined for travellers with persistent diarrhea. This subgroup of patients is less likely to respond to the standard recommendations for acute TD. The present statement specifically addresses the returned traveller with persistent diarrhea, i.e. with symptoms lasting >=14 days as defined by the World Health Organization(8). Relevant English-language articles published between October 1990 and June 1997 were identified through MEDLINE using the terms "diarrhea" and "travel"; relevant articles cited in the bibliographies were searched manually. Incidence and Etiologies of Persistent Travellers' Diarrhea The true incidence of persistent diarrhea related to travel is not known, but has been estimated to occur in 1% to 3% of those experiencing acute TD(1,6,9-11). Unfortunately, most cases of persistent diarrhea have no known etiology. Patients presenting with acute TD often suffer from bacterial infection, with bacteria accounting for 50% to 70% of cases; those with persistant TD often have post-infectious lactose intolerance or irritable bowel syndrome. The differential diagnosis of persistent diarrheal illness includes the following:
Etiologic agents, if found, are more likely to be parasitic in origin (Table 1). Certain geographic areas are notorious for specific microbes. Giardiasis is ubiquitous, yet it is most often thought of as a consequence of travel to Russia and mountainous areas of North America. Cyclosporasis has been geographically linked to Nepal; however, North American outbreaks underscore its potential widespead nature(5,12,13). Tropical sprue, a very unusual problem for travellers, is associated with prolonged travel of >1 year to high-risk areas such as Puerto Rico, Dominican Republic, Haiti, Cuba, West Indies, India, Burma, southeast Asia, and the Phillippines. Table 1 Etiology of persistent TD
Patient Evaluation Evaluation of the patient should include a complete history and physical examination, with particular emphasis on the travel itinerary and potential exposure to enteric pathogens based on assessment of the sanitary quality of water and food during travel. Note should be made of the time of the symptom onset in relation to travel. Some travellers attribute their diarrhea to their trip, when their symptoms may have antedated the trip or be only coincident with travel. A careful history of gastrointestinal symptoms antedating travel may provide an important clue to the presence of irritable bowel syndrome or other etiologies. If fever occurs in conjunction with diarrhea and a travel itinerary indicates travel to a malaria-endemic area, it is imperative to do blood smears to rule out malaria, as well as blood cultures. Note should be made of the stool quality and quantity; for example, watery, malabsorptive (semiformed, bulky, greasy, or malodorous), or bloody. Are the stools small in volume and frequent, associated with tenesmus suggesting large bowel origin, or are they voluminous and watery suggesting of small bowel pathology? Characterizing the stool quality may help to direct further investigation to the small or large bowel. In general, bloody diarrhea requires investigation as it may be associated with persistent invasive bacterial gastroenteritis, amoebiasis, or inflammatory bowel disease. Weight loss should be noted, with emphasis on the time of the weight loss in relation to the onset of diarrhea; significant weight loss suggests underlying pathology rather than irritable bowel syndrome or lactose intolerence. Other important questions include the following:
Management of the Patient Figure 1 presents an approach to the management of patients with persistent diarrhea following travel. Bacterial culture of a single stool specimen(14) as well as ova and parasite examination of three stool specimens collected on different days(15) should be undertaken. An assay for C. difficile cytotoxin should be done if there is a history of antimicrobial ingestion within the past month. While awaiting the results of these initial investigations, patients should be advised to avoid all lactose in their diet or pretreat with a commercial lactase; this may alleviate the symptoms and negate the need for further intervention. As well, they should be advised to decrease caffeine intake and increase dietary bulk. In general, profuse diarrhea should be treated with fluids to maintain hydration. For guidelines concerning the management of hydration in children, refer to the Canadian Paediatric Society's statement on the use of oral rehydration solution(16). Specific etiologic agent(s) identified in the initial investigation should be treated using appropriate published recommendations. If, however, there is no diagnosis established after appropriate investigation and dietary restrictions, then symptomatic treatment with bulk agents (e.g. metamucil), antimotility agents (e.g. loperamide) or bile-salt therapy (cholestyramine for the control of bile-salt enteritis following TD) may be considered. If these measures fail to control symptomatology, or stools are malabsorptive or bloody, or weight loss continues, then further investigation including bowel imaging, endoscopy, and biopsy should be undertaken. Upper endoscopy with small bowel biopsy can diagnose or exclude tropical sprue and may contribute to the diagnosis of other conditions that have been missed by stool examination. Sigmoidoscopy or colonoscopy may contribute to the diagnosis of such conditions as invasive amoebiasis, intestinal schistosomiasis, or inflammatory bowel disease. However, there are currently no good data to define the role of these investigations in the management of patients with persistent TD. Some experts(9) advocate trials of therapy with agents such as metronidazole or a quinolone antimicrobial if the above investigations have failed to identify an etiology for the persistent diarrhea. Recommendations Table 2 presents evidence-based medicine categories(17) for the strength and quality of evidence for each of the recommendations that follow. Table 2 Strength and quality of evidence summary sheet
References
Members: Dr. K. Kain (Chairperson); H. Birk; Ms. M. Bodie-Collins (Secretariat); Dr. S.E. Boraston; Dr. W. Bowie; Dr. H.O. Davies; Dr. J.S. Keystone; Dr. D.W. MacPherson; Dr. A. McCarthy (Executive Secretary); Dr. J.R. Salzman; Dr. D. Tessier. Ex-Officio Members: Dr. E. Callary (HC); LCdr. D. Carpenter (DND); R. Dewart (CDC); Dr. E. Gadd (HC); Dr. C.W.L. Jeanes; Dr. H. Lobel (CDC).
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Last Updated: 2002-11-08 |