Traveller's Diarrhea - Hardcover

Diarrhea is the most frequent health problem in travelers from industrialized countries who visit developing countries, especially in tropical areas of the world. The incidence of traveler's diarrhea ranges from 30 percent to 70 percent among short-term travelers, and incapacitation rates among such travelers are as high as 45 percent during travel to high-risk destinations; the rates drop dramatically at destinations with lower risk. Traveler's diarrhea has long been a problem for civilian and military travelers from industrialized countries because they often have no immunity to the pathogens to which they are exposed while traveling. The pathogens responsible for traveler's diarrhea around the world have been remarkably consistent: enterotoxigenic Escherichia coli is the most frequently isolated pathogen; others follow specific geographic risk patterns (e.g., Campylobacter jejuni in Thailand), seasonality (e.g., cyclospora during the premonsoon dry season in Nepal), or epidemics (e.g., outbreaks of infection with Norwalk-like agents on cruise ships). The editors of Travelers' Diarrhea -- Charles Ericsson, Herbert DuPont, and Robert Steffen -- are well-recognized experts in the field and have attempted to summarize an understanding of the pathogenesis and management of traveler's diarrhea. They have tried to balance perspectives on the management and treatment of traveler's diarrhea, choosing from an international panel to write multiauthored chapters. The book has five sections, which cover the following topics: the etiology and pathogenesis of traveler's diarrhea; epidemiology and clinical manifestations; prevention; treatment; and special hosts and populations. The authors' goals were to combine an erudite discussion of the history of traveler's diarrhea with state-of-the-art management and thoughts for future research that would be relevant to both the expert in travel medicine and the generalist. Unfortunately, enlisting 45 authors to write 23 chapters has led to some redundancy and to conflicting perspectives and recommendations that might make some information in the book difficult to access and interpret. One example is the approach to traveler's diarrhea caused by giardia. In chapter 4, nitazoxanide, an exciting new broad-spectrum antiparasitic agent currently licensed in the United States for use in children, is cited as being as effective as metronidazole for giardiasis and useful in metronidazole-resistant cases of giardia-induced traveler's diarrhea. Yet in chapter 22, nitazoxanide is not even mentioned as an option for persistent diarrhea caused by giardiasis in returning travelers. Nor is it included in the clinical algorithm in chapter 14 for acute diarrhea due to giardiasis. Azithromycin is an increasingly important treatment for traveler's diarrhea in pregnant women and children -- those for whom fluoroquinolones are not generally recommended. However, incorrect doses of azithromycin are given in two key tables (Table 14-2 and Table 16-2) as 500 mg three times a day for three days for self-treatment in adults instead of 500 mg daily for three days, as accurately stated elsewhere in the book. Similarly, levofloxacin, listed in Table 16-2, should be given daily, not four times a day, if used for traveler's diarrhea. Experts in travel medicine will easily recognize and modify these inconsistencies, but the general practitioner may be led astray. Practitioners of travel medicine may also appreciate the multiple perspectives on Blastocystis hominis, an organism studied for more than 80 years and still definitively unresolved as to pathogenicity; but generalists may be perplexed if attempting to find, in the index, therapeutic guidance in the case of a stool sample positive for B. hominis. In chapter 6 (entitled "Pathogenesis"), B. hominis is presented, in the experience of the authors, as a potential pathogen. The authors of chapter 18, however (referencing case-control studies in Nepal), insist that it appears "safe to ignore B. hominis as a pathogen and continue to look for and treat other causes of diarrhea." Research into the pathogenesis and treatment of traveler's diarrhea is explored in multiple chapters, including the editors' concluding chapter. Although it is not yet licensed in the United States, rifaximin is a newly developed antimicrobial agent that is highly concentrated in the intestine and appears to be as effective as ciprofloxacin in three different regions of the world, even for inflammatory traveler's diarrhea that is positive for fecal leukocytes. The editors call for studies of risk reduction, host susceptibility ("the iron stomach"), new vaccines for enterotoxigenic E. coli and shigella (some are already in phase 1 trials in the military), nonabsorbable prophylactic enteric antibiotics, and genetically modified food vaccines. Some discussion of ionizing radiation as a way to ensure food safety would have been useful. A controversial technique endorsed by the World Health Organization and the American Medical Association, ionizing radiation is a potential method of reducing the incidence of food-borne traveler's diarrhea associated with catering on cruise ships and airlines. This book is an ambitious effort to review the state-of-the-art knowledge about traveler's diarrhea and to be inclusive, with many international perspectives. To their credit, the editors observe that in the developing world, what is an irritating but generally non-life-threatening disease in travelers also causes 2 million children to die each year, making diarrheal diseases the second most serious killer of children less than five years of age. One hopes that the exciting advances in the prevention and treatment of traveler's diarrhea that are described in this book will have a positive effect on infant mortality in developing countries. Michele Barry, M.D.
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