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.

Symptoms

• 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).

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.

Causes

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.

Bacteria
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.

Parasites/Cysts
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 10a