Traveler's Diarrhea (cont.)

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What causes travelers' diarrhea?

Travelers' diarrhea usually is contracted by the ingestion of contaminated food or water. Contrary to common belief, food - not water - is the primary cause. The CDC estimates up to 80% of cases of travelers' diarrhea are caused by bacteria. The most common bacterium that causes travelers' diarrhea is enterotoxigenic E. coli, one of six classes of enterovirulent E. coli.

Most E. coli are harmless. However, there are six unique classes of E. coli that can cause inflammation of the stomach and bowels (gastroenteritis) and are termed enterovirulent. They are virulent (extremely noxious) for the intestine (or, in Greek, the enteron).

Collectively, these six classes of enterovirulent E. coli are referred to as the EEC group (enterovirulent E. coli). Each class of EEC is distinct and different from the others.

  • Enteroinvasive E. coli (EIEC) invades (passes into) the intestinal wall to produce severe diarrhea.
  • Enterohemorrhagic E. coli (EHEC) is a type of EHEC, E.coli 0157:H7 that can cause bloody diarrhea and the hemolytic uremic syndrome (anemia and kidney failure).
  • Enterotoxigenic E. coli (ETEC) is the one that causes most of travelers' diarrhea, and produces a toxin that acts on the intestinal lining.
  • Enteropathogenic E. coli (EPEC) can cause diarrhea outbreaks in newborn nurseries.
  • Enteroinvasive E. coli (EIEC) invade the epithelial cells causing diarrhea with mucus and blood.
  • Enteroaggregative E. coli (EAggEC) can cause acute and chronic (long lasting) diarrhea in children.

Other bacterial species implicated in travelers' diarrhea include Campylobacter jejuni, Shigella, and Salmonella. Viruses (including Rotavirus, Norwalk virus and other enteric viruses) less commonly are causes of travelers' diarrhea. Parasitic infections are an uncommon cause with the exception of Giardia lamblia, which should be suspected in individuals traveling to Russia or to mountainous regions of the Northern Hemisphere. Cryptosporidum, another parasite, also has been implicated as a common cause of diarrhea in visitors to St. Petersburg, Russia.

Medically Reviewed by a Doctor on 5/9/2014

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