Traveler’s diarrhea (TD) is a clinical syndrome resulting from a sanitation failure that leads to bacterial contamination of drinking water and food. It occurs during or shortly after travel, most commonly affecting persons traveling from an area of more highly developed hygiene and sanitation infrastructure to a less developed one.
TD can be caused by bacteria, parasites or viruses. A similar but less common syndrome is toxic gastroenteritis, caused by ingestion of pre-formed toxins. Bacteria represent approximately 61 percent of the microorganisms responsible for the development of TD. Enterotoxigenic Escherichia coli (ETEC), enteroaggregative Escherichia coli (E. coli), and Shigella spp. are the most common bacteria involved. Other bacteria that cause diarrhea, such as Salmonella, Campylobacter, Yersinia, Cryptosporidium, Aeromonas, and Plesiomonas spp., are isolated incidences and occur less often. Protozoan parasites such as Giardia lamblia (Giardia) may also result in diarrhea.
Pathogen isolation rates among TD studies vary from 30 percent to 60 percent. Most cases in which no pathogen is identified still respond to antibiotics, suggesting that most cases are bacterial in origin.
The most important determinant of risk is the traveler’s destination. Persons at particular high-risk include young adults, those immunocompromised, persons with inflammatory bowel disease (IBD) or diabetes, and persons taking H-2 blockers or antacids. The condition afflicts both men and women at similar rates.
TD usually resolves within three to five days, with a mean duration of 3.6 days. In approximately 20 percent of those infected, the illness is severe enough to cause bed confinement and in 10 percent of cases the illness lasts for more than one week. For those who get serious infections, TD can occasionally be life-threatening. Serious infections include bacillary dysentery, amoebic dysentery, and cholera.
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. Most TD cases begin abruptly. The illness usually results in increased frequency, volume, and weight of stool. Altered stool consistency also is common. Typically, a traveler experiences four to five loose or watery bowel movements each day. Other commonly associated symptoms are nausea, vomiting, diarrhea, abdominal cramping, bloating, low-grade fever, urgency, and malaise.
Serious side effects that require medical attention include blood or mucous in the stool, severe abdominal pain, a high fever, and severe dehydration. Dehydration can be a serious consequence, with death occurring in as quickly as 24 hours with those infected with cholera.
TD usually has a self-limited course and often resolves without specific treatment. Oral rehydration therapy is beneficial to replace lost fluids and electrolytes and highly recommended. Clear liquids, water that is purified, oral rehydration salts to replenish lost electrolytes, and carbonated water (soda) that has been left out so that the carbonation fizz is gone, are among the most highly recommended.
If diarrhea persists longer than five days despite therapy, travelers should be evaluated and treated for possible parasitic infection. There are different medications needed for bacterial dysentery, for amoebic dysentery, for Giardia and for worms. There is no current medication therapy for Cryptosporidium, which can be life threatening for those in an immunocompromised state.
Travelers can prevent the disease by adhering strictly to precautions. Maintaining good hygiene and ensuring the use of safe water — for drinking and for teeth brushing — will help keep TD at bay. Travelers should drink safe beverages such as bottled carbonated beverages, hot tea or coffee, beer, and wine, and use only safe bottled water in areas where water quality is questionable. Reports of locals filling bottles with tap water then sealing them and selling them as “purified water” has been reported in several countries.
Active intervention is sometimes needed to ensure safe water. This involves boiling water for three to five minutes (depends on elevation), filtering water with appropriate filters or using chlorine bleach (two drops per liter) or a tincture of iodine (five drops per liter) in the water.
Well-cooked and packaged foods are usually safe, if handled properly. Avoid eating unpeeled and unwashed raw fruits and vegetables. It is also advised to avoid raw or undercooked meats and seafood. Studies also show that unpasteurized milk, dairy products, mayonnaise, and pastry icings increase the risk of TD. Use extreme caution purchasing foods or beverages from street vendors or other establishments where unhygienic conditions may be present.
Treatment varies for TD. Antibiotic prophylaxis is sometimes used for those traveling to high risk areas. Antibiotics often are used to treat TD as many cases are the direct result of bacterial infiltration. Antimotility agents, such as loperamide and diphenoxylate, provide symptomatic relief and serve as useful adjuncts to antibiotic therapy. Other nonspecific agents, such as kaolin pectin, activated charcoal, and probiotics have had a limited role and varying efficacy in the treatment of TD. According to the World Health Organization (WHO), a vaccine has been developed to aid in the fight against TD. The Activax25 vaccine is a combined multivalent vaccine that contains protective antigens against Campylobacter, Shigella, and ETEC.
1. Centers for Disease Control and Prevention. Travelers' Health: Yellow Book. Health Information for International Travel. Chapter 4 - Prevention of Specific Infectious Diseases; Traveler's Diarrhea. 2005-2006. http://www2.ncid.cdc.gov/travel/yb/utils/ybGet.asp?section=dis&obj=travelers_diarrhea.htm&cssNav=browseoyb.
2. Wikipedia. Traveler's diarrhea. http://en.wikipedia.org/wiki/Traveler's_diarrhea.
3. World Health Organization. State of the art of new vaccines. Research and Development Initiative for Vaccine Research. April 2003.