Excerpt form The Harvard Medical School Health Letter

TRAVELLERS' DIARRHEA THAT CONTINUES

Turista- that bane of travellers to exotic (and not so exotic) spots-can ruin the better part of a vacation, but is usually an illness that lasts a matter of days, rather than weeks or months. Previous HMS Health Letter articles (June 1978, July 1980, November 1980) have described the most common cause of turista, toxin-producing strains of the bacterium E. coli, as well as the degree of protection afforded by taking doxycycline or Pepto Bismol while travelling. The following is intended to direct attention to several examples of more prolonged and debilitating diarrhea that may last for weeks or months after returning home- and what can be done to help. Amebiasis produces diarrhea when a protozoan (E. histolyticum) invades the lining of the colon. The symptoms, the rectal inflammation found on inspection, and the presence of blood and pus in the feces all resemble ulcerative colitis but the treatment is entirely different! For this reason, it is crucial to diagnose amebiasis, ideally by finding amebae microscopically in specimens of fresh stool or tissue. (Other tests which measure antibodies to amebae in the blood are also available.) Metronidazole (Flagyl(r)) has been found to be an effective drug for treatment and is relatively free of serious side effects. When untreated, or when misdiagnosed as ulcerative colitis and treated with steroids, amehiasis can become life-threatening. Giardiasis is a diarrheal illness that is also caused by a protozoan- in this instance the microorganism Giardia lamblia. It is generally spread by contaminated water systems (rather than food) and visitors to such disparate places as Leningrad and Aspen have fallen victim to giardiasis. Even campers using fresh stream water in the western US. have contracted giardiasis-presumably originating from the droppings of wild animals. Symptoms usually do not begin until several weeks after exposure, meaning that a traveller may be back home before he or she is stricken. The onset is usually abrupt. "Upper GI" symptoms (nausea, vomiting) are often prominent and there may be serious weight loss due not only to decreased caloric intake, but also to decreased absorption of nutrients by the giardia in the small intestine. As with amebiasis, the diagnosis of giardiasis relies upon skilled microscopic detection of the organisms either in stools which are positive in 50% of cases or in specimen. obtained via a swallowed string or tube. Effective treatment is available for giardia victims. Tropical sprue, a diarrheal disorder occurring among natives of the Caribbean, India, and Southeast Asia, is seen in visitors to these areas as well. While most commonly affecting those who have settled in for a year or more, tropical sprue has also been reported to strike persons on briefer visits. The onset is similar to turista, with explosive, watery diarrhea, fever and profound weakness. However, the improvement that occurs after a week or so is only partial-and a persistent pattern of cramping, gas, and chronic diarrhea may last for months. Over time, progressive derangement of the lining of the small intestine occurs. The resulting problems with food absorption can lead to important nutritional disturbances reflected in severe weight loss, anemia, vitamin deficiencies, etc. Although the precise cause of tropical sprue is not known, it is believed to be due to an "overgrowth" of bacteria in the small intestine. Effective treatment is available in the form of tetracycline plus folk acid. But before the right treatment can be given with confidence, the right diagnosis must be made. Here it involves testing for malabsorption and getting a tissue sample from the lining of the intestine, which can be safely done via a device at the end of a swallowed tube. IN CONCLUSION: When chronic diarrhea occurs in a returned traveller, specific, treatable causes should be sought especially when weight loss is a prominent feature of the illness.

Page Index	Prev	Page 14	Next	Issue Index