Contaminated food and drink are the major sources of stomach or intestinal illness while traveling. Intestinal problems due to poor sanitation are found in far greater numbers outside the United States and other industrialized nations.

Water
In areas with poor sanitation, only the following beverages may be safe to drink: boiled water, hot beverages (such as coffee or tea) made with boiled water, canned or bottled carbonated beverages, beer, and wine. Ice may be made from unsafe water and should be avoided. It is safer to drink from a can or bottle of beverage than to drink from a container that was not known to be clean and dry. However, water on the surface of a beverage can or bottle may also be contaminated. Therefore, the area of a can or bottle that will touch the mouth should be wiped clean and dry. In areas where water is contaminated, travelers should not brush their teeth with tap water.

Treatment of Water
Boiling is the most reliable method to make water safe to drink. Bring water to a vigorous boil, and then allow it to cool; do not add ice. At high altitudes, allow water to boil vigorously for a few minutes or use chemical disinfectants. Adding a pinch of salt or pouring water from one container to another will improve the taste.

Chemical disinfection can be achieved with either iodine or chlorine, with iodine providing greater disinfection in a wider set of circumstances. For disinfection with iodine, use either tincture of iodine or tetraglycine hydroperiodide tablets, such as Globaline®* and Potable-Aqua®*. These disinfectants can be found in sporting goods stores and pharmacies. Read and follow the manufacturer’s instructions. If the water is cloudy, then strain it through a clean cloth and double the number of disinfectant tablets added. If the water is very cold, either warm it or allow increased time for disinfectant to work.

CDC makes no recommendation as to the use of any of the portable filters on the market due to lack of independently verified results of their efficacy.

As a last resort, water that is uncomfortably hot to touch may be safe for drinking and brushing teeth after it is allowed to cool. However, many disease-causing organisms can survive the usual temperature reached by the hot water in overseas hotels.

Food
Food should be selected with care. Any raw food could be contaminated, particularly in areas of poor sanitation. Foods of particular concern include salads, uncooked vegetables and fruit, unpasteurized milk and milk products, raw meat, and shellfish. If you peel fruit yourself, it is generally safe. Food that has been cooked and is still hot is generally safe.

Infants younger than 6 months should either be breast-fed or be given powdered commercial formula prepared with boiled water.

Some fish are not guaranteed to be safe even when cooked because of the presence of toxins in their flesh. Tropical reef fish, red snapper, amber jack, grouper, and sea bass can occasionally be toxic at unpredictable times if they are caught on tropical reefs rather than in open ocean. The barracuda and puffer fish are often toxic, and should generally not be eaten. Highest risk areas include the islands of the West Indies, and the tropical Pacific and Indian Oceans (see the Destinations section).

Travelers' Diarrhea
The typical symptoms of travelers’ diarrhea (TD) are diarrhea, nausea, bloating, urgency, and malaise. TD usually lasts from 3 to 7 days. It is rarely life threatening. Areas of high risk include the developing countries of Africa (Central, East, North, Southern, and West), the Middle East, and Central America. The risk of infection varies by type of eating establishment the traveler visits—from low risk in private homes to high risk for food from street vendors.

TD is slightly more common in young adults than in older people, with no difference between males and females. TD is usually acquired through ingestion of fecal contaminated food and water.

The best way to prevent TD is by paying meticulous attention to choice of food and beverage. CDC does not recommend use of antibiotics to prevent TD because they can cause additional problems.

For treatment, oral fluids should be administered to sufferers of diarrhea. Fruit juices, soft drinks (preferably without caffeine), and salted crackers are advised. For severe dehydration, the use of an oral rehydration solution (ORS) is advised (see below). Avoid dairy products and all beverages that contain water of questionable quality.

Antimicrobial drugs such as doxycycline, and trimethoprim/sulfamethoxazole (Bactrim®, Septra®), and fluoroquinolones (Cipro®, Noroxin®) may shorten the length of illness and may especially benefit persons with severe abdominal cramping, fever, and/or bloody diarrhea. Notably, high levels of resistance in many parts of the developing world to doxycycline and trimethoprim-sulfamethoxazole now limit the utility of these drugs for persons traveling to such areas. Consult your physician for prescription and dose schedules. Antidiarrheals, such as Lomotil®* or Immodium®*, can decrease the number of diarrheal stools, but can cause complication for persons with serious infections.

It is important for the traveler to consult a physician about treatment of diarrhea in children and infants because some of the drugs mentioned are not recommended for them. The greatest risk for children, and especially for infants, is dehydration. Prevention of dehydration through administration of soups, thin porridges, and other safe beverages is advised. Infants with diarrhea who exhibit signs of mild dehydration, such as thirst and restlessness, should be given an oral rehydration solution (ORS) to drink. This is a packet of salt and carbohydrates that should be prepared following the package instructions and using boiled or treated water. It is widely available abroad. If bloody diarrhea, dehydration, fever in excess of 102° F, or persistent vomiting occurs, seek immediate medical help.

Most episodes of TD resolve in a few days. As with all diseases it is best to consult a physician rather than attempt self-medication, especially for pregnant women and children. Travelers should seek medical help if diarrhea is severe, bloody, or does not resolve within a few days or if it is accompanied by fever and chills or if the traveler is unable to keep fluids intake up and becomes dehydrated.