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Traveler's diarrhea

Symptoms | Causes | Prevention | Treatment | Sources

Traveler's diarrhea (TD) (Dysentery) is a sudden intestinal infection that travelers often get when they are not used to microorganisms in the water supply or on the food in another country. It may be called gastroenteritis, Montezuma's Revenge, Turista, or the GI Trots.

High-risk destinations include most of the developing countries of Latin America, Africa, the Middle East, and Asia.


  • loose stools, as many as three to ten per day
  • stomach cramps
  • bloating and gas
  • nausea and vomiting 15%
  • dysentery (bloody stools) 2-10%
  • fever 2-10%
  • weakness
  • dehydration (excessive loss of body fluids)
  • headache (sometimes).
TD is slightly more common in young adults than in older people.

The diarrhea usually stops on its own within 1 to 5 days. Rarely, it lasts 2 to 3 weeks. If a fever lasts more than 24 hrs. and there is no improvement after 48 hours, you should see a doctor.


- Most cases of diarrhea are caused by an infection in the digestive tract: the stomach, small intestine, and large intestine. The most common cause of the infection is bacteria (e.g. E. coli) and less frequently, parasites (e.g. Giardia, Amoeba), fungi, toxins or viruses. They usually come from ingesting contaminated food or drinks.

Sometimes, diarrhea is not due to infection, but perhaps too much sun, fruit or booze.

Backcountry Hiking: The Giardia parasite is the number one problem, but cryptosporidium parasites and bacteria can also be present. Viruses are infrequent.
Developing Countries: Bacteria are more common, but parasites and viruses are also present.

Common bacteria include E. coli (common in most developing countries), salmonella, shigella (bacillary dysentery) and Vibrio parahaemolyticus (from raw or poorly cooked seafood common on Caribbean cruise ships and in people traveling in Asia). These bacteria produce potent toxins that cause damage to the lining of the intestine. Cholera, another bacteria, is a very rare cause of diarrhea amongst travellers.

When you are exposed to new varieties of E. coli bacteria (different than the ones in your intestine normally), the bacteria produce toxins that interfere with your intestine's ability to absorb water, thus causing diarrhea.

Cryptosporidium protozoa oocyst E. coli outbreaks have been associated with hamburger meat and unpasteurized milk. Salmonella has been associated with raw meats, poultry, eggs, milk and dairy products, fish, shrimp, frog legs, yeast, coconut, sauces and salad dressing, cake mixes, cream-filled desserts and toppings, dried gelatin, peanut butter, cocoa, and chocolate.

There are two main types of intestinal parasites: helminths and protozoa. Helminths are worms with many cells. There are two major types flatworms or Platyhelminthes (flukes and tapeworms) and the roundworms or Nematoda. Usually, helminths cannot multiply in the human body and will eventually clear up without infecting you again. Nematode infections are a problem in China particularly in the Yangtze River valley. The mode of transmission varies with the type of worm; it may involve ingestion of eggs or larvae, penetration by larvae, bite of vectors, or ingestion of stages in the meat of intermediate hosts. Cases have been reported from eating contaminated sushi, particularly salmon. Protozoa have only one cell. They can multiply inside the human body.
Protozoa include amoeba (e.g. Entamoeba histloytica), flagellates (e.g. giardia lamblia) and sporozoa (e.g. cyclospora and cryptosporidium).

In secondary hosts, the parasite becomes encysted in muscle and brain tissue; only felines carry the parasite in the intestinal tract and shed oocysts that sporulate in the environment. The oocysts are 10a12µm in diameter and can survive in water and moist soils for long periods of time.
Oocysts of Cryptosporidium and cysts of Giardia occur in the aquatic environment throughout the world. They have been found in most surface waters, where their concentration is related to the level of faecal pollution or human use of the water.

Oocysts, the environmentally resistant transmission stage of the parasite, are shed by infected hosts with their faeces and are immediately infectious. They may remain in the environment for very long periods without loss of infectivity: a very robust oocyst wall protects the sporozoites inside against physical and chemical damage. When an oocyst is ingested by a new host, excystationaopening of the suture in the oocyst walla is triggered by the body temperature and the interaction with stomach acid and bile salts.

See Cryptosporidium Life Cycle at the CDC.

Hepatitis A is the most common but will take 10-50 days for symptoms to occur.
Hepatitis E is common in many third world countries.
Norwalk virus can also come from shellfish and salads. Other virus' include rotavirus, cytomegalovirus, polio and herpes simplex virus.

Campylobacter jejuni (C. jejuni) can be in chicken and raw milk.

Some species of fish and shellfish can contain poisonous biotoxins, even when well cooked. The most common type of biotoxin in fish is ciguatoxin. The flesh of the barracuda is the most toxic laden and should always be avoided. Red snapper, grouper, amberjack, sea bass, and a wide range of tropical reef fish contain the toxin at unpredictable times. The potential for ciguatera poisoning exists in all subtropical and tropical insular areas of the West Indies and the Pacific and Indian Oceans where the implicated fish species are eaten. Ciguatera, a bacteria, can also come from fish.

See Also: Germs - Microbes - Pathogens



  • Do not drink untreated water, including ice cubes in drinks. *
    See Water Treatment below.
  • Always wash your hands thoroughly after using the toilet and before eating. Keep your mouth closed in the shower. Alcohol swabs or a disefectant soap like Purell are handy for this. You can also use them to clean eating utensils and the neck of water bottles.
  • Brush your teeth with bottled water. (Note: most toothpastes contain antibacterial substances so it may be OK to use tap water if you do not swallow it.)
  • Eat only foods that are thoroughly cooked and still hot, or fruits and vegetables that you peel yourself. Avoid foods which have been pre- cooked and reheated
  • Do not eat raw or partially cooked fish or shellfish, including such dishes as ceviche. Fully cooked fish and shellfish are safe.
  • Carbonated soft drinks and water, bottled water *, wine, and beer are usually safe as long as you do not add ice.
  • Avoid salads which may have been washed in untreated water.
  • Avoid food and beverages from street vendors.
  • Avoid Milk and other dairy products unless you can be sure they have been pasteurized and stored properly.
  • Assume all water is contaminated.
  • Water can be made safe either by boiling for at least 10 minutes or use 2% iodine drops to sterilize for 30 minutes. Current tests indicate only 1 min. of boiling is enough. Iodine may not kill some bacteria. There are new options.
* (Note: In some countries locals have been known to refill and reseal bottled water with unsafe water.)

Herbal and other medication

Garlic - Garlic has antibacterial, antiviral, and anti-fungal activity. Garlic has been demonstrated to kill parasites, including amoeba and hookworm. Garlic is a broad-spectrum antibiotic that even blocks toxin production by germs. [Journal Nutrition, March 2001] It can also benefit digestion, help with symptoms of common cold and flu, and lower cholesterol and blood pressure.

Because of garlic's anti-clotting properties, persons taking anticoagulant drugs should check with their doctor before taking garlic.

Goldenseal - Japanese research found goldenseal extract to be very effective against intestinal bacteria. It contains the alkaloid berberine, which appears to be effective even against giardia, a tenacious parasite responsible for many serious gastrointestinal infections.

Vitamin C
Vitamin C should be the buffered alkaline form (mineral ascorbates) rather than the acidic form (ascorbic acid) and should be combined with bioflavonoids which prolong vitamin C's action in the blood circulation. The powdered form of vitamin C is recommended to achieve optimal dosing. A tablespoon of vitamin C powder (about 10,000 mgs.) can be added to juice. Good products are Twinlab's Super Ascorbate C powder and Alacer's powdered vitamin C.

Bismuth subsalicylate, taken as the active ingredient of Pepto-Bismol® (2 ounces four times a day, or two tablets four times a day), has decreased the incidence of diarrhea by about 60% in several placebo-controlled studies. (Source: CDC)

Antiperistaltic agents (drugs that slow movement through the bowel) (for example, Lomotil® and Imodium®) are NOT effective in preventing TD.

Antibiotics including doxycycline, trimethoprim/sulfamethoxazole (TMP/SMX), trimethoprim alone, and the fluoroquinolone agents ciprofloxacin and norfloxacin, when taken prophylactically have been 52% to 95% effective in preventing TD caused by bacteria. However, most doctors don't recommend taking them as a preventative unless you are at high risk.

Some people eat more yogurt for several weeks before travel.
Review of three separate studies found that eating yogurt boosts immunity. Yogurt's active bacteria may hold the key to this. Source: The Walking Magazine, June 2001

Evidence is mounting that some of the bacteria contained in yogurt can prevent and treat diarrhea. They may also ease other ailments of the intestinal tract, and some researchers now advocate using these beneficial bacteria -- "probiotics" -- as medicine.

Some yogurt is pasteurized after fermentation which kills the bacteria. Look for the "Live and Active Cultures" seal established by the National Yogurt Association. This seal means that the product contains a significant amount of active cultures, to the tune of 100 million cultures per gram of yogurt.

See Probiotics and Yogurt
Acidophilus, a bacteria added to many yogurts can also be obtained in tablets;
See Acidophilus - The Friendly Bacteria

Other Herbs Several other herbs are traditionally used for treatment of parasites, including male fern (Dryopteris filix-mas), tansy (Tanacetum vulgare), wormwood, black walnut green hulls (Juglans nigra), pumpkin seeds, pawpaw (Papaya) and cloves (Syzygium aromaticum).

Black Walnut May be a remedy for stomach cramps, diarrhea, and parasites. May treat acne, herpes, warts, poison ivy, fungal infections, cold sores.

There are a variety of "Para" (parasite fighting) products with a combination of herbs, such as black walnut, pumpkin seeds, pawpaw (Papaya), garlic, cloves, and others for cleansing the intestinal tract and improving the immune system such as ParaCan from General Health, Para 90, PARASystem and other products from Nature's Plus.

Local Teas - In some places you can get local herbal teas which help to avoid digestive tract problems.

Water Treatment
Water can be treated with chemicals or filtering:
Water Purification Tablets:
Filtering doesn't work with viruses because of their small size.
See Water Purification in recreation.

chlorine (cyst forming protozoa [Cryptosporidium andgiardiasis]
are extremely resistant to chlorination.)
Active carbon (AC) filters remove large particles and adsorb low molecular weight organics
and chlorine .
Micropur MP1 ClO2


Even before the diarrhea is treated, you must try to prevent dehydration, which often follows diarrhea and can cause serious problems. Dehydration occurs when your body loses more fluids and salts (electrolytes: sodium and potassium) than it takes in. Oral rehydration therapy (ORT) is first course of action.

  • Drink plenty of fluids, containing some sugar, to prevent dehydration.
  • Drink clear broth or eat salted crackers to compensate for loss of salt.
  • Avoid milk products.
  • If you have bloody stools, seek medical attention.
  • Ask your doctor to provide a stand-by treatment.
  • Try an oral rehydration method:
    a) Gastrolyte sachets are available in Australia but I couldn't find them elsewhere.
    b) Alternately drink the contents of glasses No. 1 and No. 2
    Glass no. 1: 8 oz. fruit juice 1/2 tsp. corn syrup or honey and a pinch of salt
    Glass no. 2: 8 oz. boiled water 1/4 tsp. baking soda
    or c) Mixing 1 liter of clean (or boiled) water, 2 tablespoons of sugar, 1/4 teaspoon salt, and 1/4 teaspoon of baking soda.

An antidiarrheal drug should be started promptly if significant diarrhea occurs, defined as three or more loose stools in an 8-hour period. Avoid antidiarrheals if possible, you need to clean out your system as quickly as possible. An antibiotic should only be started if you have more than 10-20 loose stools per day.

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, medical attention should be sought.
Travel Vacs at Aventis,
Traveler's Diarrhea at Health Information Library at Saint John's Health Center


Fluroquinolones such as Cipro® (ciprofloxacin) or Noroxin® (norloxacin) are the present drugs of choice for bacterial infections (except salmonella).
You may want to ask your doctor for a prescription and take it with you.
These medicines can cause side effects, including sun sensitivity, and tendon problems. Inflammation and ruptures of the shoulder, hand, and Achilles tendons have been reported.

Gabboral (250 mg.) is an antibiotic available in some Latin American countries which will work.

It is important to continue to take antibiotics for the time prescribed, otherwise the more robust bacteria may survive leading to antibiotic resistant strains.

The drug of choice for amebic dysentery is Flagyl® (Metronidazole). (See: parasitology at McGill Univ.)
Note: Amebic dysentery takes 1-2 weeks to develop symptoms, so you may not need to take it along for short trips. My Infectious disease physician said you should only take Flagyl under the guidance of a doctor after your return.


  Antimotility agents: Imodium AD® and Lomotil®.
(Since these reduce the "motility," or motor activity in the intestines, they're known as "antimotility" medications.) They will reduce the symptoms to make travel easier, but if you don't have to travel it is probably better to not use them and get the toxins out of your system as quickly as possible. Antimotility agents shouldn't be used if bloody stools or a fever are present. In addition, they should not be used for more than 48 hours or taken by children less than two years of age.

Use over-the-counter medications in foreign countries with caution.

Bismuth subsalicylate (Pepto-Bismol): converted to ismuth carbonate which coats.

Kaolin/pectin (Kaopectate®, K-peck) absorbs toxins.
A few bites of peeled green apple--high in pectin--can be substituted in a pinch. However, Kaolin and pectin do not appreciably reduce diarrhoea duration, stool frequency, or stool losses. They may also stop antibiotics from working properly.

Activated charcoal absorbs toxins. Most commonly used for poisoning, including Paralytic Shellfish Poisoning (PSP), drug overdoses and proposed for certain bioterrorism agents such as Ricin and Trichothecene. It adsorbs and inactivates a number of organic and inorganic compounds by binding them in the gut. But there is no clinical evidence that it shortens diarrhoea duration or reduces the number or volume of stools. Like other adsorbents, it also binds to and makes other drugs such as tetracycline inactive, and affects digestive enzymes and intestinal micronutrients.

Avoid alcohol, coffee, and all milk products (milk, cheese, cream, pudding, etc.) most vegetables, fruits (citrus, tomatoes, etc.), red meats, and heavily seasoned foods. If you have no diarrhea after 6 to 12 hours, slowly begin to eat clear soup, salted crackers, dry toast or bread, and milk-free sherbet.

Over the next few hours to 1 to 2 days, slowly add bananas, applesauce, rice, baked potato, and low-fat chicken soup with rice or noodles, and any plain noodles or pasta to your diet. After about 3 days your stools will begin to have shape an you may resume your normal diet, cautiously adding milk products and high fiber foods.

There is also evidence that yogurt taken as a treatment will help.

Sources of Information for the above:

Travelers' Diarrhea and Food and Water Precautions at 
    the Center for Disease Control (CDC)
Bad Bug Book -
 Foodborne Pathogenic Microorganisms and Natural Toxins Handbook at the FDA.
Meet the Bugs at Nutrition Action Health Letter
Travel Vacs at Aventis,
Traveler's Diarrhea at Health Information Library at Saint John's Health Cntr.
Medical Information for Americans Traveling Abroad from the State Dept.
Protozoa as Human Parasites
Helminths: Pathogenesis and Defenses
All About Diarrhea
Dialogue on Diarrhoea at the Rehydration Project
Dr Strakrle's Infectous diesases and Travel Medicine page for the Czech Rep.
Germs - Microbes - Pathogens
Cipro is a registered trademark of Bayer Corporation, Imodium is a registered trademark of McNeil-PPC, Kaopectate and Flagyl are Registered Trademarks of Pharmacia & Upjohn Co., Lomotil is a registered trademark of G.D. Searle LLC A subsidiary of Pharmacia Corp., Noroxin is a registered trademark of Merck & Co., Inc., Pepto-Bismol is a Registered Trademark of Procter & Gamble.

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last updated 24 Apr 2006