Information on Traveler's Diarrhea
The prospect of developing diarrhea is a major concern for travelers heading to developing countries. "Traveler's diarrhea" (TD) occurs in up to 40% of travelers and is characterized by the passage of 3 or more unformed stools in a 24-hour period. Although it is usually a self-limited disease, TD lasts an average of 3-4 days. Ten percent of cases last longer than 1 week, and approximately 2% last a month or more.
Despite prevention strategies including the traditional advice to help avoid diarrhea ("boil it, cook it, peel it, or forget it"), TD still occurs. Therefore, it is important to learn how to recognize and manage TD if it occurs.
Organisms that cause TD
TD is caused by bacteria, viruses and less commonly parasites (protozoa) that are ingested by eating contaminated food or beverages. For short-term travelers in most areas, bacteria are the cause of the majority of diarrhea episodes. (In most parts of the world, Enterotoxic E. coli is the most common cause of bacterial diarrhea.) Protozoa are an uncommon cause of TD in short-term travelers. Depending on the season, however, protozoa can account for 10-20% of diarrhea in longer-term travelers and expatriates. (Giardia lamblia is the most common protozoal pathogen.) Gastrointestinal viruses (rotavirus, Norwalk, etc.) exist throughout the world, and their importance varies in different regions. However, they probably account for no more than 5-10% of TD cases.
You can get TD whenever you travel from countries with a high level of hygiene to countries that have a low level of hygiene. Poor sanitation, the presence of stool in the environment, and the absence of safe restaurant practices lead to widespread risk of diarrhea from eating a wide variety of foods in restaurants. It is important to follow the traditional advice given to travelers to help avoid diarrhea (see "Food and Beverage Precautions," below); however, in high-risk destinations the fecal contamination may involve a wide variety of foods, and simply adhering to this advice may not prevent illness.
Your destination is the most important determinant of risk. Developing countries in Latin America, Africa, the Middle East, and Asia are considered high risk. Most countries in Southern Europe and a few Caribbean islands are deemed intermediate risk. Low risk areas include the United States, Canada, Northern Europe, Australia, New Zealand, and several of the Caribbean islands
Persons at particularly high risk for TD include young adults (because they are prone to risk-taking behavior and often are on limited budgets); persons with immune suppression, inflammatory bowel disease, or diabetes; and persons taking medications that decrease gastric acidity.
The vast majority of TD is bacterial. Bacterial diarrhea has an abrupt onset of uncomfortable diarrhea. Fever, nausea, or vomiting may occur. "Abrupt onset" generally means that you are aware of the exact time of day the illness began, and the symptoms are quite bothersome from the beginning.
In contrast, protozoal diarrhea begins gradually, with looser stools occurring in distinct episodes during the day (for example, mornings and evenings), gradually becoming more bothersome and associated with fatigue. Persons with protozoal infections often do not seek medical care for 2 weeks or more due to the generally mild nature of the symptoms.
If you experience an abrupt onset of uncomfortable diarrhea you can be reasonably confident that the cause is bacterial, and you can treat yourself with an appropriate antibiotic (as provided by your travel health physician) to shorten the illness.
- Eat at establishments that are known to cater to foreigners or that are known by other foreigners to be safe.
- Eat foods that are well-cooked and served steaming hot.
- Eat breads, tortillas, crackers, biscuits, and other baked goods.
- Eat fruits, nuts, and vegetables with thick skins, peels, or shells that you remove yourself.
- Eat canned foods.
- Always wash your hands with soap before eating and after using the toilet.
Travelers should NOT:
- Eat any food from street vendors or market stalls.
- Eat leafy or uncooked vegetables and salads. Some organisms in soil and water are not destroyed by normal cleaning methods.
- Eat undercooked, raw, or cold meat, seafood, or fish.
- Eat large carnivorous fish, especially from reef areas (barracuda, red snapper, amberjack, surgeon fish, parrot fish, mullet, sea bass, grouper, or moral eels). Many contain concentrated toxins.
- Eat or drink unpasteurized dairy products such as cheese, yogurt, or milk. Be particularly wary of ice cream and other frozen confections that may have been made or stored in contaminated containers.
- Eat cold sauces such as mayonnaise, salad dressing, chutneys, or salsas, which are usually raw and made by hand.
- Eat buffet foods such as lasagna, casseroles, and quiches—unless you know they are fresh (not reheated) and have been kept steaming hot. Avoid buffets where there are no food covers or fly controls.
- Eat creamy desserts, custards, or sauces that may not have been adequately refrigerated.
In developed countries, clean drinking water is available right out of the tap and breakdowns in the system are rare. Developing countries, however, don't always have the resources needed to ensure a pure water supply, and consequently tap water is not safe to drink. Even if the people who live there can drink the water, travelers should not assume that they can. Local residents have built up immunity to organisms in the water, but visitors have not. As a result, tap water can make travelers sick.
When traveling through areas with less than adequate sanitation or with water sources of unknown purity, you can reduce the chance of illness by following these precautions.
- Use only water that is sealed and bottled or chemically treated, filtered, or boiled – for drinking and for brushing teeth.
- Drink beverages made only with boiled water whenever possible (such as hot tea and coffee). Water boiled for any length of time (even 1 minute), at any altitude, is safe to drink.
- Purify your own water (see "Treating Water," below) if one of these options is not available. Decide which method to use for water purification and bring along the appropriate equipment.
- Carry safe water with you if you are going out for the day and safe water is not assured.
- Breast-feeding is the safest food source for infants who are still nursing. If formula is used, it must be prepared with boiled water and sterilized containers.
Travelers should NOT:
- Drink tap water.
- Rinse toothbrush in tap water.
- Use ice unless it is made from boiled, bottled, or purified water. Freezing does not kill the organisms that cause diarrhea.
- Assume that water is safe because it is chlorinated. Chlorination does not destroy all the organisms that can make you ill.
- Drink from wet cans or bottles—the water on them may be contaminated. Dry wet cans/bottles before opening and clean all surfaces that will have contact with the mouth.
- Drink fruit juice unless it comes directly from a sealed container; otherwise it may have been diluted with tap water.
Urban travelers may choose an immersion coil for boiling water (a plug adapter and current converter might be necessary).
If it is not possible to boil water, chemical disinfection is an alternative. Most (but not all) diarrhea pathogens are susceptible to being killed by iodine or chlorine dioxide (Pristine), which can be used to disinfect water, leafy vegetables, and fruits.
In 2003 the vaccine Dukoral was introduced in Canada for the prevention of TD caused by ETEC and against most strains of cholera. Although more effective against Cholera it can protect against 50% of severe forms of bacterial TD.
It is taken in a liquid form ( 0days-7days) with a booster every 3 months if TD protection is still needed. Cholera protection lasts for 2 years after the initial series. It should be considered for all high risk exposures and for high risk individuals
Prophylactic antibiotics are not routinely recommended for travelers, Antibiotic prophylaxis may be recommended in special circumstances: for individuals who have a particularly high risk of acquiring diarrhea, persons who face serious consequences if they do develop diarrhea (those with underlying illnesses), or persons who have a short-term work assignment that would make diarrhea a disaster. Such prophylaxis generally is restricted to periods of less than a week. The most effective antibiotics for prevention of TD are the ciprofloxacin, zithromycin, norfloxacin, ofloxacin, and levofloxacin.
If a social situation arises in which food may have to be accepted that may not be safe to eat, you may consider selective use of a single dose of prophylactic antibiotic (after the offending incident), but only if you clearly understand the risks and benefits.
In general, however, you are better off learning how to self-diagnose and treat TD early with the appropriate antibiotic in order to try to limit the illness to a single day.
For prevention, bismuth subsalicylate can be taken (as an ingredient of Pepto-Bismol) in liquid form (2 oz., 4 times per day) or as tablets (2 tablets, 4 times per day). Its use has decreased the incidence of TD by about 60% in several studies, but it is not recommended for more than 3 weeks when used for prophylaxis. Side effects are minimal and may include temporary black stools or a black tongue. Nausea and constipation may occur occasionally, and, rarely, there is ringing in the ears. Do not take bismuth subsalicylate if you have an allergy to aspirin, renal insufficiency or gout, or are taking anticoagulants, probenecid, or methotrexate. Bismuth subsalicylate can prevent absorption of doxycycline so the two should not be taken at the same time. Bismuth subsalicylate is not approved for use in children less than 3 years of age.
Taking live lactobacillus strains has been shown to produce a mild decrease in the rate of TD. These strains appear to have little in the way of side effects.
Self-Diagnosis & Self-Treatment
The majority of cases of TD are due to bacteria and the majority of bacteria causing TD are currently sensitive to ciprofloxacin (with the exception of some Campylobacter species). Therefore it is not necessary to know specifically which bacteria is causing the diarrhea. It is sufficient to classify treatable TD as bacterial or protozoal.
Traveler’s diarrhea in adults is not usually associated with significant dehydration, but replacement of fluids remains a cornerstone of self-treatment. At the same time, any diarrhea that is severe enough to pose a risk of dehydration should be considered for antibiotic treatment (see below). Dehydration can be corrected with any fluid, and you should drink any available appropriate fluid while oral rehydration fluid is sought. Commercial ORS are available in ,most countries. If commercial ORS is not readily available, you can make your own replacement solution by drinking alternating glasses of these fluids--glass #1: drink 8 oz. fruit juice plus ½ tsp corn syrup or honey or sugar plus a pinch of salt; glass #2: drink 8 oz. boiled water plus ¼ tsp baking soda. This should be followed by a light diet as the condition improves ( toast-tea-apple sauce-rice). Avoid dairy products.
Travelers are often in areas where prompt, effective medical care is unavailable. Therefore, it is often more practical to self-treat with antibiotics purchased prior to leaving for the trip. The use of antibiotics can turn a 3- or 4-day illness into a 1-day illness.
For treatment of suspected bacterial diarrhea:
- Ciprofloxacin ( 1 or 3 days of therapy)
- Azithromycin : Can be used as an alternate for children under 12 and pregnancy and in areas of increasing incidence of quinolone-resistant campylobacter. such as Thailand.
Bowel immobilizers such as loperamide (Imodium) are often used to manage the symptoms of TD. Bowel immobilizers sometimes induce prolonged constipation even at low doses, and they can lead to a bloated, uncomfortable feeling if taken for moderately severe infections without taking an antibiotic as well. Their use should be discontinued if symptoms last more than 48 hours or if there is blood in the stools.