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Travelers’ diarrhea (TD) is the most common travel-related illness experienced in people traveling abroad. Following simple recommendations such as “boil it, cook it, peel, it, or forget it,” may help reduce the incidence of (TD) but studies have found that people who follow these measures may still become ill. Poor hygiene practice in local restaurants is likely the largest contributor to the risk for TD.
(TD) is an illness that can result from a variety of intestinal pathogens. Bacterial pathogens are the predominant risk, thought to account for 80-90 percent of (TD). Intestinal viruses have been isolated in studies of (TD), but they usually account for only 5-8 percent of illnesses. Protozoal pathogens are slower to cause symptoms and are thought to account for approximately 10 percent of diagnoses in longer-term travelers.
The most important risk factor for contracting (TD) is travel destination. There are regional differences in both the risk for and cause of diarrhea. The world is generally divided into 3 grades of risk: low, intermediate, and high.
Bacterial diarrhea presents with the sudden onset of symptoms that can range from mild cramps and loose stools to severe abdominal pain, fever, vomiting, and bloody diarrhea. Viral caused diarrhea presents in a similar fashion to diarrheal illnesses caused by bacterial pathogens. Protozoal diarrhea, often has a more gradual onset, 1-2 weeks, with milder symptoms, usually 2-5 loose stools per day.
Untreated bacterial diarrhea usually lasts 3-5 days while untreated viral diarrhea lasts 2-3 days. Protozoal diarrhea can persist for weeks to months without treatment.
To avoid illness, travelers should select food with care. Raw or undercooked meat, fish, and shellfish can carry various intestinal pathogens. Particularly in areas where hygiene and sanitation are inadequate, travelers should avoid salads, uncooked vegetables, unpasteurized fruit juices, and unpasteurized milk and milk products, such as cheese and yogurt. Eat only food that is fully cooked and served hot and fruit that has been washed in clean water and then peeled by the traveler. Raw fruits that are eaten unpeeled (such as strawberries) or cut should be avoided, and fruits that are eaten peeled (such as bananas) should be peeled by the person who eats them. Always refrigerate perishable cooked food within 2 hours (1 hour at temperatures >90 F. Cooked food that has been stored should be thoroughly reheated before serving. These recommendations also apply to eggs, which should be thoroughly cooked, whether they are served alone or used in sauces. Food and beverages obtained from street vendors has been associated with an increased risk of illness.
Travelers should wash their hands with soap and water before eating and after using the bathroom If soap and water are not available, use an alcohol-based hand sanitizer (with >60% alcohol).
In many parts of the world, tap water contains disease-causing contaminants, including viruses, bacteria, and parasites. As a result, tap water in some places may be unsafe for drinking, preparing food and beverages, making ice, cooking, and brushing teeth.
Avoid drinking tap water unless there is reasonably certaity it is not contaminated. Some people choose to disinfect or filter their water when traveling to destinations where safe tap water may not be available. Water contaminated with fuels or toxic chemicals, however, will not be made safe by boiling or disinfection; travelers should use a different source of water if they suspect this type of contamination.
In areas where tap water may be contaminated, commercially bottled water from an unopened, factory-sealed container or water that has been adequately disinfected should be used for brushing teeth and other oral hygiene.
Beverages made with boiled water and served steaming hot (such as tea and coffee) are generally safe to drink. When served in unopened, factory-sealed cans or bottles, carbonated beverages, commercially prepared fruit drinks, water, alcoholic beverages, and pasteurized drinks generally can be considered safe. Because water on the outside of cans and bottles may be contaminated, they should be wiped clean and dried before opening or drinking directly from the container.
Beverages that may not be safe for consumption include fountain drinks, fruit drinks made with tap water, iced tea, and iced coffee. Because ice may be made from contaminated water, travelers in areas with unsafe tap water should request that beverages be served without ice.
The primary medication used for prevention of (TD) is bismuth subsalicylate (BSS), which is the active ingredient in Pepto-Bismol. Studies from Mexico have shown this agent (taken daily as either 2 oz of liquid or 2 chewable tablets 4 times per day) reduces the incidence of (TD) by approximately 50%. BSS commonly causes blackening of the tongue and stool and may cause nausea, constipation, and rarely ringing in the ears. BSS should be avoided by travelers with aspirin allergy, renal insufficiency, and gout and by those taking blood thinners, probenecid, or methotrexate. Studies have not established the safety of BSS use for periods >3 weeks.
Since bacterial causes of (TD) far outnumber other microbial causes, antibiotics are often used in the treatment for (TD). Travelers to low and intermediate risk countries should bring along an antibiotic, prescribed by a provideer, to be started promptly if significant diarrhea occurs. Significant diarrhea is defined as three or more loose stools in an 8-hour period or five or more loose stools in a 24-hour period, especially if associated with nausea, vomiting, cramps, fever or blood in the stool. Seek medical attention if diarrhea is severe or bloody, or if fever occurs with shaking chills, or if abdominal pain becomes marked, or if diarrhea persists for more than 72 hours. Though effective for treating (TD), antibiotics are not recommended to as a preventive measure.
* Most cases of travelers' diarrhea are mild and do not require either antibiotics or antidiarrheal drugs. Adequate fluid intake is essential.
Antimotility agents provide symptomatic relief in (TD). An agent such as loperamide can reduce the frequency of loose stools while awaiting the effects of antibiotics. The safety of loperamide when used along with an antibiotic has been well established. although antimotility agents such as Loperamide are not recommended for people experiencing bloody diarrhea or those who have diarrhea and fever.Oral Rehydration Therapy
Fluids and electrolytes are depleted with TD, and replenishment is important. Rereplacement of fluid helps the traveler feel better more quickly. Travelers should remember to use only beverages that are sealed, treated with chlorine, boiled, or are otherwise known to be purified. For severe fluid loss, replacement is best accomplished with oral rehydration solution (ORS), prepared from packaged oral rehydration salts, such as those provided by the World Health Organization, which are widely available at stores and pharmacies in most developing countries. ORS is prepared by adding 1 packet to the indicated volume of boiled or treated water. In mild cases of (TD), rehydration can be maintained with any palatable liquid (including sports drinks), although overly sweet drinks, such as soda, can make diarrhea worse if consumed in large volumes.