Eliot C. Heher, MD
Global travel can be extremely enjoyable, but it also creates some health risks for the traveler, including most commonly Travelers’ Diarrhea, or TD for short. (This is a condition with many other names, such as Montezuma’s Revenge, for example). This column will focus on basic information about TD and the food and water precautions you should follow to avoid this scourge. Next time I’ll focus on the treatment of TD.
TD is extremely common–striking 30-70% of travelers to developing countries–and the best evidence is that nearly all cases are caused by infectious agents, such as viruses, bacteria, and protozoa. The two most common symptoms are diarrhea and abdominal cramping. Nausea and vomiting, bloating, malaise, fever and blood in the stool also occur. TD usually strikes quickly, typically during the first week of your trip, but can occur upon return home. Most cases last 3-4 days, untreated, and 90% resolve within a week. According to the CDC, the risk of acquiring TD is highest when you travel to developing countries in Latin America, Africa, the Middle East and Asia. Intermediate risk destinations include countries in Southern Europe and several Caribbean islands. Low-risk destinations include Canada, Northern Europe, Australia, New Zealand, the United States and many of the more developed Caribbean Islands.
TD is spread through fecally contaminated food, primarily, and water. Obviously the risk of contamination occurring is highest in places without adequate sanitation facilities. High risk foods include raw and undercooked meats, seafood, raw fruits and vegetables. Tap water, ice and unpasteurized milk and dairy products such as cheese may be associated with increased risk of TD. Where you eat also seems to matter. Highest risk: street vendors: Lowest risk: food prepared in private homes.
If you are pregnant or traveling with small children, you will need to be extra careful. Please discuss your situation with a physician prior to leaving home.
Here are some specific suggestions on avoiding TD:
Research your destination to better understand the risk of TD there. Sources of destination information on the Web include the Centers for Disease Control (www.cdc.gov) and Shoreland, Inc. (www.tripprep.com)
Select food carefully. If you are traveling in an area where sanitation may be inadequate, avoid raw food, salads, uncooked vegetables, unpasteurized milk and milk products such as cheese.
Food that is steaming hot (above 59 degrees Celsius) is safe but must not be allowed to sit at room temperature for extended periods prior to consumption. Some physicians recommend that travelers use a thermometer to test food–and send food that has not achieved this temperature back to the kitchen for additional heating. Peeled fruits, especially those containing Vitamin C (ascobic acid) are safe as long as you do the peeling. Dry foods such as breads are safe—as are foods with high sugar content. A useful phrase to remember: “Cook it, peel it, boil it, or forget it”.
Water that has been adequately chlorinated will kill most bacteria and viruses but not all potential pathogens. Check with your local contacts about the purity of the tap water in your destination. Safe beverages include those made with boiled water (such as coffee and tea), canned or bottled carbonated beverages, especially those with flavorings such as soft drinks (carbonation makes the drink acidic, which kills bacteria and other organisms); and beer and wine. Of course, there are other good reasons not to drink exclusively beer and wine during your trip, and adding alcohol to an otherwise contaminated drink will not sterilize it.
Drinking directly from the can or bottle is ok as long as you clean and dry the outside of the container first.
Non-carbonated bottled water may be contaminated–again, check with your local contacts to see what bottled water, if any, is safe. Say “no” to ice cubes because freezing does not kill these organisms–and make sure not to brush your teeth with contaminated water.
To purify your own water, boiling is best though you must do so vigorously (some sources recommend that you boil for at least one minute, and that at higher altitudes you also use chemical disinfection). Alternatives to boiling include chemical disinfection (with iodine or various commercially available agents– use these as a short term solution only) or filtration. These two options are topics in and of themselves and will require some research on your part to understand the procedures and precautions. Many camping stores carry a large selection of filters and chemical agents for water purification. Some filters remove protozoa such as Giardia and others don’t, so you’ll have to investigate.
Wash your hands frequently with soap and water–but remember that the person who prepared your lunch may not extend you the same courtesy.