Chapter 2The Pre-Travel ConsultationCounseling & Advice for Travelers
Food & Water Precautions
Contaminated food and water often pose a risk for travelers. Among the infectious diseases that travelers can acquire from contaminated food and water are Escherichia coli infections, shigellosis or bacillary dysentery, giardiasis, cryptosporidiosis, norovirus infection, hepatitis A, and salmonelloses, including typhoid fever. Contaminated food and water can also pose a risk of cholera, rotavirus infection, and a variety of conditions caused by protozoan and helminthic parasites. Many infectious diseases transmitted through food and water can be acquired directly through the fecal–oral route. Accidental ingestion or contact with recreational water from lakes, rivers, oceans, and inadequately treated swimming pools can also spread many of the above diseases, as well as some infections of the ears, eyes, skin, and respiratory or nervous systems (see Chapter 3 for specific infectious diseases).
To avoid illness, travelers should be advised to select food with care. All raw food is subject to contamination. Particularly in areas where hygiene and sanitation are inadequate, travelers should be advised to avoid salads, uncooked vegetables, and unpasteurized milk and milk products, such as cheese. Travelers should eat only food that has been fully cooked and is still hot, and fruit that has been washed in clean water and then peeled by the traveler. Undercooked and raw meat, fish, and shellfish can carry various intestinal pathogens. Cooked food that has been allowed to stand for several hours at ambient temperature can provide a fertile medium for bacterial growth or be recontaminated by food-handling techniques, so it should be thoroughly reheated before serving. These recommendations also apply to eggs, which should be thoroughly cooked, whether they are served alone or used in sauces. Consumption of food and beverages obtained from street vendors has been associated with an increased risk of illness. Travelers should wash their hands or use alcohol-based hand cleaners (with ≥60% alcohol) before eating, after using the bathroom or changing diapers, and after direct contact with preschool children, animals, or feces.
The easiest way to guarantee a safe food source for an infant aged <6 months is to breastfeed the infant. If the infant has already been weaned, formula prepared from commercial powder and boiled water is the safest and most practical food (see Chapter 7, Travel and Breastfeeding).
Travelers should be advised not to bring perishable seafood from high-risk areas upon their return to the United States. Cholera cases have occurred in people who ate crab that had been brought into the United States from Latin America by travelers. Moreover, travelers should not assume that food and water aboard commercial aircraft are safe, since food and water may be obtained in the country of departure, where items may be contaminated.
In many parts of the world, particularly where water treatment, sanitation, and hygiene are inadequate, tap water may contain disease-causing contaminants, including viruses, bacteria, and parasites. As a result, tap water in some places may be unsafe for drinking, preparing food and beverages, making ice, cooking, and brushing teeth. Contaminated tap water may also cause illness if inadvertently swallowed or inhaled during showering or bathing. Infants, young children, pregnant women, the elderly, and people whose immune systems are compromised because of AIDS, chemotherapy, or transplant medications may be especially susceptible to illness from some contaminants.
Travelers should avoid drinking or otherwise ingesting tap water unless reasonably certain it is not contaminated. Many people choose to disinfect or filter their water when traveling to destinations where safe tap water may not be available (see the Water Disinfection for Travelers section later in this chapter). Water contaminated with fuel or toxic chemicals, however, will not be made safe by boiling or disinfection; travelers should use a different source of water if they suspect this type of contamination.
In areas where tap water may be contaminated, commercially bottled water from an unopened, sealed container, or water that has been adequately disinfected should be used for brushing teeth and other oral hygiene. Travelers who may be at increased risk for legionellosis, such as elderly or immunocompromised people, may choose to avoid areas such as showers or hot tubs where Legionella can be aerosolized and inhaled.
Beverages made with boiled water and served steaming hot (such as tea and coffee) are generally safe to drink. When served in unopened, sealed cans or bottles, carbonated beverages, commercially prepared fruit drinks, water, alcoholic beverages, and pasteurized drinks generally can be considered safe. However, reports exist of apparently sealed bottles or cans from commercial sources that, when opened, contained contaminated products. Because water on the outside of cans and bottles may be contaminated, they should be wiped clean and dried before opening or drinking directly from the container.
Beverages that may not be safe for consumption include fountain drinks, fruit drinks made with tap water, iced tea, and iced coffee. Because ice may be made from contaminated water, travelers should request that beverages be served without ice.
Pathogens that cause a variety of infections (gastrointestinal, respiratory, dermatologic, aural, ocular, and neurologic) can be transmitted by ingesting, inhaling mists or aerosols of, or having contact with contaminated water while swimming, wading, or participating in other recreational water activities in oceans, lakes, rivers, pools, water parks, fountains, and hot tubs. Water contaminated by sewage, animal waste, wastewater runoff, or human feces from swimmers can appear clear and clean but still contain disease-causing pathogens. Ingesting even small amounts of such water can cause illness. Travelers should avoid ingesting any water in which they are swimming, wading, or participating in other recreational water activities. They also should not swim with open cuts, abrasions, or other wounds that could serve as entry points for pathogens. To protect other swimmers, children and adults with diarrhea should not swim or wade in the water to avoid contaminating it.
Travelers should not swim or wade 1) in water that may be contaminated with human or animal feces or sewage; 2) near storm drains; 3) after heavy rainfall; 4) in freshwater streams, canals, and lakes in schistosomiasis-endemic areas of the Caribbean, South America, Africa, and Asia (see Map 3–14); 5) in bodies of water that may be contaminated with urine from animals infected with Leptospira; or 6) in seawater, with an open wound or abrasion. When swimming, diving, or participating in similar activities in warm freshwater (including lakes, rivers, ponds, hot springs, or thermally polluted water near power plants and industrial complexes), travelers should prevent water from entering the nose by wearing a nose clip or by not submerging the face or head. Naegleria fowleri is found in warm freshwater around the world; infections are rare but often fatal (www.cdc.gov/parasites/naegleria).
Maintaining proper disinfectant (such as chlorine and bromine) and pH levels is necessary to prevent transmission of pathogens in treated recreational water venues such as pools, water parks, fountains, and hot tubs. Travelers should avoid such locations if the water is cloudy. If the water is clear, travelers may choose to use test strips to check chlorine and pH levels. Even if recreational water has been properly disinfected, travelers still should avoid ingesting any water in which they are swimming, wading, or participating in other recreational water activities. Because some pathogens, such as Cryptosporidium, can survive even in well-maintained pools, people with diarrhea should not swim or enter treated recreational water.
Maintaining disinfectant levels in hot tubs is difficult because the high water temperature depletes disinfectants. Legionella (see Chapter 3, Legionellosis) and Pseudomonas, which can cause “hot tub rash” and “swimmer’s ear,” can multiply in recreational water venues in which disinfectant levels are not properly maintained. Travelers can use test strips to check chlorine and pH levels, and may choose to avoid hot tubs where bather limits are not enforced or where the water is visibly cloudy.
- Backer H. Water disinfection for international and wilderness travelers. Clin Infect Dis. 2002 Feb 1;34(3):355–64.
- Cartwright R, Colbourne J. Cryptosporidiosis and hotel swimming pools—a multifaceted challenge. Water Science and Technology: Water Supply. 2002;2(3):47–54.
- CDC. Drinking water: camping, hiking, travel. Atlanta: CDC; 2010 [cited 2010 Nov 8]. Available from: http://www.cdc.gov/healthywater/drinking/travel/index.html.
- CDC. For swimmers and hot tub users. Atlanta: CDC; 2010 [cited 2010 Nov 8]. Available from: http://www.cdc.gov/healthywater/swimming/pools/for-swimmers-hot-tub-users.html.
- CDC. Healthy swimming/recreational water. Atlanta: CDC; 2010 [cited 2010 Nov 8]. Available from: http://www.cdc.gov/healthywater/swimming/index.html.
- CDC. Legionellosis resource site. Atlanta: CDC; 2009 [cited 2010 Nov 8]. Available from: http://www.cdc.gov/legionella/.
- CDC. Parasites—Naegleria. Atlanta: CDC; 2008 [cited 2010 Nov 8]. Available from: http://www.cdc.gov/parasites/naegleria/.
- CDC. Vibrio vulnificus. Atlanta: CDC National Center for Zoonotic, Vector-Borne, and Enteric Diseases; 2009 [updated 2009 Nov 12; cited 2010 Nov 23]. Available from: http://www.cdc.gov/nczved/divisions/dfbmd/diseases/vibriov/.
- Eberhart-Phillips J, Besser RE, Tormey MP, Koo D, Feikin D, Araneta MR, et al. An outbreak of cholera from food served on an international aircraft. Epidemiol Infect. 1996 Feb;116(1):9–13.
- Finelli L, Swerdlow D, Mertz K, Ragazzoni H, Spitalny K. Outbreak of cholera associated with crab brought from an area with epidemic disease. J Infect Dis. 1992 Dec;166(6):1433–5.