Diseases

Since food is the major source of infection, close attention to diet is of foremost importance in the prevention of travelers' diarrhea. Foods should be well-cooked and served warm. Raw vegetables, uncooked meat or seafood, and other foods maintained at room temperature should be avoided. Dairy products, tap water and ice (including frozen drinks not made from filtered water) are also high-risk foods. Carbonated beverages, beer and wine, hot coffee and tea, fruits that can be peeled, and canned products generally are safe. The risk for developing diarrhea increases when eating at restaurants and when purchasing food from street vendors. Also, frequent hand washing with soap and clean water will decrease the likelihood of the bacteria's spread, especially to other people that the person may be traveling with. Antibiotics can be effective in preventing travelers' diarrhea, but are not recommended for most people due to possible side effects (see "How is Travelers' Diarrhea Treated?"). Bismuth subsalicylate (Pepto-Bismol) also can be effective in preventing diarrhea in travelers although Pepto-Bismol may cause black stools and, rarely, ringing in the ears. People allergic to aspirin should avoid Pepto-Bismol. Studies have not shown bismuth subsalicylate to be safe for use longer than three weeks. Probiotics such as Lactobacillus have shown inconclusive results in prevention of travelers' diarrhea.

Twenty percent to fifty percent of travelers may develop diarrhea depending on the region of the world they visit. Diarrhea is the most common illness of travelers, affecting 10 million people each year, according to the Centers for Disease Control (CDC). In general, travelers at risk for diarrhea commonly come from industrialized nations and travel to high-risk areas that are primarily within developing or less industrialized nations of the world, including Latin America, Africa, the Middle East, and Asia. Areas of lesser risk include China and some Caribbean nations. Travel to areas of the United States, Canada, Northern Europe, and Australia pose the lowest risk to travelers. Men and women are at equal risk for developing travelers' diarrhea. Younger individuals are more commonly afflicted, perhaps because of more adventurous eating habits. People with disorders that compromise their immune system (such as HIV, cancer, chemotherapy, steroid use), people with diabetes, and people with underlying abdominal disorders (irritable bowel syndrome, colitis) are more susceptible to travelers' diarrhea. People taking acid blockers for their stomachs (for example, famotidine [Pepcid], cimetidine [Tagamet], omeprazole [Prilosec], esomeprazole [Nexium]) also have a higher susceptibility to travelers' diarrhea because they have less stomach acid to protect them from the bacteria that cause the condition.

The presumptive diagnosis of travelers' diarrhea is based solely on the development of diarrhea when visiting a part of the world where this condition is common among travelers. The diarrhea usually is mild, self-limited, and resolves spontaneously. Symptoms usually can be controlled with over-the-counter medications (see below.) Only when the diarrhea is severe or complicated, and possibly when antibiotics are contemplated, should attempts be made to identify the exact organism responsible for the diarrhea so that the correct drug therapy can be selected. Identification may be difficult or impossible in undeveloped countries because of the lack of medical laboratories. When laboratories are available, the stool can be examined for parasites and cultured for bacteria. Identification of the pathogen results in the definitive diagnosis.

Although prophylactic antibiotics (antibiotics taken before the person is exposed to the pathogen) are effective in preventing travelers' diarrhea, they generally are not recommended. The side effects of antibiotics, including photosensitivity (sensitivity to the sun that results in injury to the skin) and additional diarrhea can be major problems. Antibiotic prophylaxis can be considered in individuals with underlying medical diseases in whom diarrhea is more likely to occur or who may be profoundly affected by the diarrhea. This group includes people with previous stomach surgery, active inflammatory bowel disease, underlying immunodeficiency conditions, and other serious medical disorders. In these situations drugs of the quinolone class (ciprofloxacin [Cipro, Cipro XR, Proquin XR], levofloxacin [Levaquin]) have been shown to be effective.Bismuth subsalicylate (Pepto-Bismol) in liquid or pill form also has been shown to be effective in preventing diarrhea in up to 65% of travelers although Pepto-Bismol may cause black stools and, rarely, ringing in the ears. People allergic to aspirin should avoid Pepto-Bismol.When treating afflicted individuals, drugs that alleviate symptoms as well as antibiotics play a role. With moderate symptoms, the addition of Pepto-Bismol alone may suffice. Alternatively, anti-diarrheal agents such as diphenoxylate and atropine (Lomotil) or loperamide (Imodium) can be given. With severe disease, characterized by frequent diarrhea or dehydration, or complicated by the passage of bloody stools, Lomotil or Imodium should not be used and you should consult your doctor.Oral fluids are a mainstay of therapy since they are important to prevent dehydration. Tips for staying hydrated are:

• Small, frequent sips of clear liquids (those you can see through) are the best way to stay hydrated.
• Avoid alcoholic, caffeinated, or sugary drinks, if possible. Over-the-counter rehydration products made for children such as Pedialyte and Rehydralyte are expensive but good to use if available.
• Sports drinks such as Gatorade and PowerAde are fine for adults if they are diluted with water because at full strength they contain too much sugar, which can worsen diarrhea.
• Try to drink at least as much or more fluid than you think is coming out or lost with the watery diarrhea.
• For mild to moderate dehydration, oral rehydration salts (ORS) may be recommended. These are available in pharmacies in most developing countries. Severe hydration usually requires emergent intravenous rehydration (IV).
• If the affected individual cannot hold down fluids, or is losing fluids faster than they can take them in, seek medical care immediately, because some patients will require IV hydration.

Children and the elderly are more susceptible to dehydration. If a person feels light-headed or woozy, feels a rapid pulse or their mouth and lips are dry, they should consult a physician. If a child is listless, not eating or drinking and does not make wet diapers or urinate within a few hours they also should be seen quickly by a doctor.

The symptoms of travelers' diarrhea vary. Generally, diarrhea occurs within the first week of travel and lasts up to three to four days. Affected individuals on average pass up to five loose or watery bowel movements per day which may be associated with cramps. On occasion, individuals may experience fever or bloody stools. The diarrhea may be accompanied by abdominal pain and cramping, bloating, or increase in stomach or intestinal noises or gurgling (borborygmi).

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) to 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 and elsewhere.

The prognosis for travelers' diarrhea is usually good. Most cases resolve within 2 days without treatment. The CDC estimates 90% of cases resolve within one week, and 98% resolve within one month. Travelers' diarrhea is rarely fatal.

Travelers' diarrhea is defined by most experts as three or more unformed stools in a 24 hour time period, passed by a person who is traveling. Travelers' diarrhea is commonly accompanied by abdominal cramps, nausea, and bloating. Travelers' diarrhea is a general term and does not specify any cause. Travelers' from temperate regions of the world frequently experience diarrhea four days to two weeks after arriving in certain other areas of the world. Other terms used to describe this illness include "Montezuma's Revenge," the "Aztec Two Step," and "Turista" in Mexico, the "Delhi Belly" in India, and the "Hong Kong Dog" in the Far East.