TD is particularly common among people traveling to Asia (except for Japan and Singapore), the Middle East, Africa, Mexico, and Central and South America. The risk is moderate in Southern Europe, Russia, and China. TD has been linked to later irritable bowel syndrome and Guillain–Barré syndrome. It has colloquially been known by a number of names, including "Montezumas revenge," the "Nile runs" and "Delhi belly". Signs and symptoms
The onset of TD usually occurs within the first week of travel, but may occur at any time while traveling, and even after returning home, depending on the incubation period of the infectious agent. Bacterial TD typically begins abruptly, but Cryptosporidium may incubate for seven days, and Giardia for 14 days or more, before symptoms develop. Typically, a traveler experiences four to five loose or watery bowel movements each day. Other commonly associated symptoms are abdominal cramping, bloating, fever, and malaise. Appetite may decrease significantly. Though unpleasant, most cases of TD are mild, and resolve in a few days without medical intervention.Blood or mucus in the diarrhea, significant abdominal pain, or high fever suggests a more serious cause, such as cholera, characterized by a rapid onset of weakness and torrents of watery diarrhea with flecks of mucus (described as "rice water" stools). Medical care should be sought in such cases; dehydration is a serious consequence of cholera, and may trigger serious sequelae—including, in rare instances, death—as rapidly as 24 hours after onset if not addressed promptly. Causes
Infectious agents are the primary cause of travelers diarrhea.
Though many travelers find a four-times-per-day regimen inconvenient, lower doses have not been shown to be effective. Potential side effects include black tongue, black stools, nausea, constipation, and ringing in the ears. Bismuth subsalicylate should not be taken by those with aspirin allergy, kidney disease, or gout, nor concurrently with certain antibiotics such as the quinolones, and should not be taken continuously for more than three weeks. Some countries do not recommend it due to the risk of rare but serious side effects.A hyperimmune bovine colostrum to be taken by mouth is marketed in Australia for prevention of ETEC-induced TD. As yet, no studies show efficacy under actual travel conditions.Though effective, antibiotics are not recommended for prevention of TD in most situations because of the risk of allergy or adverse reactions to the antibiotics, and because intake of preventive antibiotics may decrease effectiveness of such drugs should a serious infection develop subsequently. Antibiotics can also cause vaginal yeast infections, or overgrowth of the bacterium Clostridium difficile, leading to pseudomembranous colitis and its associated severe, unrelenting diarrhea.Antibiotics may be warranted in special situations where benefits outweigh the above risks, such as immunocompromised travelers, chronic intestinal disorders, prior history of repeated disabling bouts of TD, or scenarios in which the onset of diarrhea might prove particularly troublesome. Options for prophylactic treatment include the quinolone antibiotics (such as ciprofloxacin), azithromycin, and trimethoprim/sulfamethoxazole, though the latter has proved less effective in recent years. Rifaximin may also be useful.