Prevention and treatment of traveler's diarrhea: a clinical pharmacological approach.

Diarrhea represents a major health problem for travelers to developing countries. Although the syndrome is usually self-limited and recovery occurs in the majority of cases without any specific form of therapy, there is a need for safe and effective ways of preventing and treating it. Since the syndrome is most often caused by an infection acquired by ingesting fecally contaminated food or beverages, precautions regarding dietary habits remain the cornerstone of prophylaxis, but dietary self-restrictions do not always translate to reduced rates of diarrheal illness. Administration of probiotics (e.g. lactobacilli or Saccharomyces boulardii) and immunoprophylaxis with the newer oral cholera vaccines have been tried with promising results. Antimicrobials remain, however, the most successful form of prophylaxis, being effective in up to 90% of travelers. For those with impaired health who will take prophylaxis, systemic agents with proved efficacy should be recommended. For other otherwise healthy persons, poorly absorbed agents are preferable in order to avoid the serious, albeit rare, toxicity of systemic drugs. The key factor in the management of acute watery traveler's diarrhea, particularly in infants and young children, is the restoration of water and electrolyte balance. This does not reduce the duration of the illness but will limit dehydration and prevent acidosis. Many patients will require no additional therapy, whereas some will need pharmacologic treatment to shorten the duration of diarrhea or to relieve the accompanying symptoms, like abdominal discomfort, nausea and vomiting. A typical 3- to 5-day illness can be reduced to approximately 1 day by trimethoprim-sulfamethoxazole (TMP-SMX) combination. Some other systemic antimicrobials have been successfully used but, during the last few years, the 4-fluoroquinolone drugs have received considerable attention and have been shown to be highly effective in reducing the duration of traveler's diarrhea. These antimicrobials may become the best option for adults. The safest choice remains the use of poorly absorbed antimicrobials. Unfortunately, however, only a few compounds (i.e. bicozamycin and furazolidone) have been specifically tested in the therapy of traveler's diarrhea. Others (e.g. nifuroxazide or rifaximin), which have been found effective in various homeland forms of infective diarrhea deserve to be evaluated in specifically designed clinical trials. Persons visiting developing countries where the risk of traveler's diarrhea is high should be recommended to bring an antidiarrheal compound or bismuth subsalycilate, if available, and an antibacterial agent. For infants, children and the elderly, in whom dehydration may occur rapidly and be particularly dangerous, oral rehydration solutions are indicated.