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Travel to developing countries

Description

An in-depth report on travel-related health risks and how to prepare ahead of time to reduce these risks.

Alternative Names

Cholera; Dengue fever; Traveler's diarrhea; Malaria; Schistosomiasis; Typhoid; Yellow fever

Traveler's Diarrhea

Traveler's diarrhea (TD) is the most common health problem a traveler encounters. It is almost always caused from ingesting certain organisms in contaminated food or water. Diarrhea can also be caused -- particularly in children -- by anxiety, stress, allergies, fatigue, and diet changes.

Symptoms and Course

Diarrhea frequently occurs within the first week of travel but may develop at any point, including after returning home. TD causes four or five loose or watery stools per day. Vomiting may also occur. It usually lasts 3 or 4 days, but about 14% of cases last longer. In rare cases, TD lasts more than 3 months. When TD lasts a long time, it can cause postinfectious irritable bowel syndrome. TD is rarely life threatening, although it can be severely debilitating, especially in children. Weakness, reduced urine output, lightheadedness, and mental changes require immediate medical attention, especially in children. Life-threatening symptoms are reduced levels of consciousness, seizures, and coma.

Risk by Country

Traveler's diarrhea typically affects 40 - 60% of people from industrialized nations who visit developing countries:

• High-risk destinations include most of the developing countries of Latin America, Africa, the Middle East, and Asia. The risk varies widely, however. In different studies, 73% of children who traveled to Africa, 61% who went to India, 55% of travelers to Asia, and 39.5% of travelers to South America experienced diarrhea.
• Intermediate-risk destinations include most Southern European countries and a few Caribbean islands.
• Low-risk destinations include Canada, Northern Europe, Australia, New Zealand, the United States, and some Caribbean islands.

Infectious Causes

A number of infectious organisms, including bacteria, parasites, and viruses, can cause diarrhea in travelers. These organisms are most often transmitted through contaminated food and water. Bacteria and viruses cause diarrhea within a few hours and up to 3 days, while diarrhea from parasites can occur 7 - 14 days after exposure. In about 10 - 50% of cases, the cause of TD is unknown.

• The most common bacterial cause of traveler's diarrhea is Escherichia coli ( E. coli ). Certain strains of this organism are toxic to the intestines. E. coli accounts for 20 - 50% of cases. It is found in soil, water, and milk and occurs in major regions in the worlds, with the highest rates in Latin American and the lowest in Asia. Diarrhea caused by E. coli is generally explosive, non-bloody, and accompanied by nausea, vomiting, cramps, and fever.
• Noroviruses, also called Norwalk-like viruses, are an increasingly common cause of traveler’s diarrhea in countries such as Mexico and Guatemala, and on cruise ships. Recent studies of travel in these destinations rank noroviruses second to E. coli for causing diarrhea.
• Shigella is the bacterial cause of dysentery , affecting 15% of travelers. It is common in countries experiencing natural disasters, socioeconomic upheaval, or during other times when sanitary food and water are hard to find. Shigella causes bloody, mucus-laden diarrhea along with fever, cramps, and exhaustion.
• Campylobacter is a very common food- and water-borne bacterial cause of diarrhea in certain regions, notably Thailand and Morocco, during the winter.
• Giardia is a parasite found in contaminated water in every country in the world. It can cause chronic diarrhea lasting for several weeks, causing vague pain, weight loss, excessive burping, bloating, and fatigue.
• Entamoeba histolytica is a parasite prevalent Mexico, India, Africa, and Central and South America. It produces small stools that contain blood and mucus. If the condition becomes chronic, it can resemble inflammatory bowel disease (IBD). It is important to distinguish the two, since corticosteroids used to treat IBD can have dangerous effects in people carrying the parasite.
• Additional common culprits are the bacteria Salmonella, parasites (Cryptosporidiosis, Cyclospora. microsporidia), and rotavirus (usually in Latin America).

Water Precautions

Drinking contaminated water is the most common cause of acquiring TD-causing bacteria. The following methods or products help reduce exposure to contaminated water.

• Boiling water is the best method for eliminating infectious organisms. There is some debate about how long to boil, but bringing the water to a good boil for at least 1 minute generally renders it safe to drink. Travelers might consider buying an electric heating coil to boil and purify tap water. (A plug adapter or voltage converter may be needed).
• Carbonated bottled water may be used for brushing teeth and drinking. Carbonation increases the acid in the water and kills bacteria. Plain bottled water may not be safe, since it can be taken from contaminated sources. Even ice cubes can carry infection.
• Iodine tablets such as Polar Pure, Globaline, or Potable-Aqua purify water. Water may be purified by adding one iodine tablet to a quart of water 30 minutes before drinking it. Adding 50 mg of vitamin C will eliminate the iodine taste and color. Purifying is not effective against parasites such as Cyclospora and Cryptosporidium .
• Small portable water filters remove parasites and clear murky water without leaving a chemical taste. They are particularly beneficial for pregnant women and people who cannot take iodine. Filtering does not prevent viruses from passing through. When purchasing a filter, the phrase "EPA Registration" should be printed on the label, indicating that the U.S. Environmental Protection Agency has guaranteed its effectiveness.
• Newer portable water purification systems, such as SteriPEN, use ultraviolet light to disinfect water. These handheld devices can destroy bacteria, viruses, and protozoa, such as giardia and cryptosporidium.
• In all cases, do not swim in water that may be contaminated or contain parasites.

Food Precautions

Some important tips:

• Seek restaurants with a reputation for safety.
• Heated food should be hot to the touch and eaten promptly.
• Beware of sliced fruit that may have been washed in contaminated water.
• Don't buy food from street vendors.
• Peel all fresh fruits and vegetables yourself.
• Vegetables may also be rinsed with diluted soapy water, soaked in a halide solution, and rinsed in purified water. (Certain fruits, such as strawberries, raspberries, and grapes should never be considered safe, even when washed.)
• Avoid dairy products.
• Avoid raw or undercooked meat and fish.
• Avoid cold toppings and sauces -- even bottled sauces on tables. In one study, two-thirds of tabletop sauces in Mexico were contaminated. (Forty percent of sauces on tables in Houston, Texas, were also contaminated.)
• Avoid tap water and ice cubes.
• Avoid fruit juices, fresh salads, unpasteurized dairy products, and open buffets.

Preventive Drugs

There is no vaccine against traveler's diarrhea. However, vaccination against cholera has been shown to offer some protection against TD in 25% of travelers .

The following drugs can reduce your chance of getting sick:

Pepto-Bismol . Taking two tablets of Pepto-Bismol four times a day before and during international travel can help prevent many cases of diarrhea. Pepto-Bismol should not be taken for more than 3 weeks. Both aspirin and Pepto-Bismol share the active ingredient salicylate, which can be harmful to children. Many medications interfere with salicylate, and people who are allergic to aspirin, pregnant women, and those who have ulcers, other bleeding disorders, or gout, should not take Pepto-Bismol without consulting a doctor. Side effects of Pepto-Bismol include ringing in the ears and black stools and tongue.

Prophylactic Antibiotics. Prophylactic antibiotics are those used to prevent diarrhea while traveling. They work well, but there are many reasons that argue against their routine use. Taking prophylactic antibiotics can trigger adverse drug reactions, development of superinfections, and can contribute to bacterial resistance. Antibiotics are also not effective against parasites or viruses and may give travelers a sense of false security. At this time, prophylactic antibiotics are not generally recommended unless the person is at increased risk for complications of TD, including people with chronic bowel diseases, kidney disease, diabetes, or HIV.

Researchers are studying whether prophylactic antibiotics should be used more often. In a 2005 study of travelers to Mexico, 15% of patients who took preventive doses of the antibiotic rifaximin (Xifaxan) developed traveler’s diarrhea compared with 54% of patients who received placebo (sugar pill). Rifaximin was approved in 2004 for treatment of diarrhea caused by E. coli .

Lactobacilli. Taking capsules that contain protective bacteria called lactobacilli (also called probiotics), may be helpful, although the Infectious Diseases Society of American believes that evidence is insufficient to recommend them. Some studies report that a genetically engineered strain called Lactobacillus rhamnosus strain GG may prevent and reduce severity of diarrhea. In fact, lactobacilli may be used for both prevention and treatment in children without any adverse effects. The capsules can be split open and put into beverages for small children.

Treatment for Diarrhea

Fluid Replacement. If diarrhea develops, prevention of dehydration is the most important first step, particularly in children. In severe cases, dehydration can be life threatening. Agitation may be an early symptom. Listlessness and a weak pulse are symptoms of severe dehydration. Parents should seek medical help immediately if the child appears to be dehydrated.

Fluid replacement must use solutions that contain the important minerals potassium, sodium, and calcium. The following are some suggestions:

• A useful recipe for fluid replacement calls for two glasses of fluid: the first containing 8 oz. of fruit juice, 1/2 tsp. of honey or corn syrup, and a pinch of salt; the second filled with 8 oz. of purified or carbonated water and 1/4 tsp. of baking soda. The traveler should drink alternately from each glass until the thirst is quenched.
• Parents with small children should bring commercial oral rehydration solutions such as Pedialyte, Lytren, Gastrolyte, or Ricelyte. Products containing rice flour work slightly faster than others. If the child finds the taste unpleasant, adding a half-teaspoon of Jell-O or Kool Aid to sweeten the solution may help and does not appear to reduce its benefits.
• Adding a soluble fiber supplement and eating as soon as possible helps the intestine to absorb water and is beneficial for children and adults.
• Children with diarrhea should not drink apple juice, colas, or sports beverages, which do not contain the proper balance of salts and sugar.

Helpful Foods. Foods that help slow diarrhea include rice, wheat, bananas, salted crackers, and mashed potatoes.

Adding milk (but not soymilk) to these foods may help many children. In fact, eating yogurt that contains active lactobacilli cultures may have positive benefits. (However, yogurt drinks in less developed countries may carry a high risk for contamination.)

Bismuth subsalicylate (Pepto-Bismol). Pepto-Bismol can be used for treatment of mild diarrhea and nausea. Treatment generally consists of 1 fluid ounce or 2 tablets every 30 minutes for up to 8 doses in a 24-hour period. If diarrhea continues, treatment can be repeated for a second day.

Antimotility Drugs. Antimotility drugs provide prompt but temporary symptomatic relief by reducing muscle spasms in the gastrointestinal tract. They include:

• Loperamide (Imodium) is the agent of choice, even when used in combination with antibiotics
• Diphenoxylate (Lomotil)
• Opiates (such as paregoric, tincture of opium, and codeine). Opiates are often poorly tolerated, and can affect the central nervous system.

Antimotility drugs should be discontinued if symptoms persist beyond 48 hours and should not be used at all in patients with high fever, if there is blood in the stool, or in children under age 2. Imodium is approved for children 2 years and up, but its use in children is controversial because of reports of severe side effects. Experts do not recommend it.

Note. Lomotil and Imodium work well for treating diarrhea, but are not effective for prevention. Lomotil may even increase the risk for it.

Antibiotics. Antibiotics are generally effective for treating traveler's diarrhea that develops in an 8-hour period, with three or more loose stools, and especially if associated with nausea, vomiting, abdominal cramps, fever, or blood in the stools. Because antibiotics are prescription drugs, travelers at risk should obtain them before they depart and should receive directions for self-treatment while abroad. Antibiotics should not be used for nausea and vomiting when diarrhea is not present. Although self-treatment is generally safe, a doctor should be sought for any child with diarrhea and for adult patients who develop fever or bloody diarrhea. (Antibiotics are generally not useful for diarrhea in developed nations, since such cases are likely to be caused by viruses.)

In general, patients take one tablet every 12 hours for 5 days. Fluoroquinolones are the preferred antibiotic, unless the person is traveling to SE Asia or India, where bacterial resistance to this class of drugs is high. In these cases, azithromycin (Zithromax) is preferred. Taking a single dose of an antibiotic such as ofloxacin (Floxin), plus an anti-motility drug (usually Imodium), often provides relief within 24 hours for many patients. Other antibiotics used for diarrhea include ciprofloxacin (Cipro), rifaximin (Xifaxan), levofloxacin (Levaquin), and azithromycin (Zithromax).

Parasites do not usually respond to standard antibiotics. Trimethoprim-sulfamethoxazole (Bactrim), for example, has fallen out of favor for routine use because of resistant bacteria, but it may be very effective against the severe diarrhea caused by the parasite Cyclospora . Metronidazole (Flagyl) is the standard drug for Giardia . Erythromycin and similar antibiotics may be useful for Cryptosporidium or Campylobacter . Nitazoxanide is another antibiotic showing promise for treating diarrhea caused by parasites. Antibiotics do not work for diarrhea caused by viruses.

Experimental Drugs. Racecadotril (Tiorfan), also called acetorphan, reduces water and electrolyte loss in the intestine. Studies report that the drug is safe and effective although it must be used in combination with rehydration solutions. Comparison studies suggest that racecadotril is equal to or only slightly less effective then loperamide (Imodium) and causes less constipation and bloating. Racecadotril also seems to be safe in small children, while Imodium should not be used in this population. Racecadotril may not be effective against certain parasites such as Cryptosporidium. However, it is not available in the U.S.

• Review Date: 1/23/2007
• Reviewed By: Harvey Simon, MD, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital

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