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Chapter 2 The Pre-Travel Consultation Counseling & Advice for Travelers

Food & Water Precautions

John C. Watson, Michele C. Hlavsa, Patricia M. Griffin

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 and a variety of conditions caused by protozoan and helminthic parasites. Many of the infectious diseases associated with contaminated food and water are caused by pathogens transmitted via the fecal-oral route. Swallowing, inhaling aerosols of, or coming in contact with contaminated water, including natural saltwater or freshwater or the water in inadequately treated swimming pools, interactive fountains (splash parks or splash pads), or hot tubs or spas can transmit these and other pathogens that can cause diarrhea, vomiting, or infection of the ears, eyes, skin, or the respiratory or nervous system (see Chapter 3 for specific infectious diseases).

FOOD

To avoid illness, travelers should be advised to select food with care. All raw food is subject to contamination. Raw or undercooked meat, fish, and shellfish can carry various intestinal pathogens. In areas where hygiene and sanitation are inadequate or unknown, travelers should be advised to avoid eating salads, uncooked vegetables, unpasteurized fruit juices, and unpasteurized milk and milk products, such as cheese and yogurt. In these areas, travelers should be advised to eat only food that is fully cooked and served hot and fruit that has been washed in clean water and then peeled by the traveler. Raw fruits that are eaten unpeeled (such as strawberries) or cut should be avoided, and fruits that are eaten peeled (such as bananas) should be peeled by the person who eats them. Always refrigerate perishable cooked food within 2 hours (1 hour at temperatures >90°F [32°C]). Cooked food that has been stored 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 with soap and water before eating, after using the bathroom or changing diapers, after caring for someone who is ill, and after direct contact with preschool-age children, animals, or feces. If soap and water are not available, use an alcohol-based hand sanitizer (with ≥60% alcohol) and wash hands with soap and water as soon as they become available. Alcohol-based hand sanitizers are not very effective against Cryptosporidium and norovirus and may not work well when hands are heavily soiled.

The safest way to feed an infant aged <6 months is to breastfeed exclusively. If the infant is fed formula prepared from commercial powder, the powder should be reconstituted with hot water at a temperature of ≥158°F (≥70°C). This precaution will kill most pathogens with which the infant formula may have been contaminated during manufacturing or through handling after opening. To ensure that the water is hot enough (≥158°F; ≥70°C), travelers should prepare formula within 30 minutes after boiling the water for ≥1 minute (see the Water Disinfection for Travelers section later in this chapter). The prepared formula should be cooled to a safe temperature for feeding (for example, by placing the bottle upright in a bath of safe water and safe ice [see below], keeping the bath water below the nipple ring) and using within 2 hours of preparation. Bottles and nipples should be washed and then sterilized (in boiling water or in an electric sterilizer). Travelers may wish to pack enough formula for their trip, because manufacturing standards vary widely around the world.

Travelers should be advised not to bring perishable seafood from high-risk areas back to the United States. Cholera has 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, because food and water may be obtained in the country of departure, where hygiene and sanitation may be inadequate.

WATER

Drinking Water and Other Beverages

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, including droplets and aerosols, may also cause illness if inadvertently swallowed or inhaled, as can occur 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 disease-causing organisms (such as Cryptosporidium and Legionella).

Travelers should avoid drinking or otherwise ingesting tap water unless they are 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). Tap water is not sterile and should not be used for sinus or nasal irrigation or rinsing, including use in neti pots and for ritual ablution (see Chapter 4, Saudi Arabia: Hajj Pilgrimage) unless it is disinfected for these purposes (see www.cdc.gov/parasites/naegleria/ritual-ablution.html and www.cdc.gov/parasites/naegleria/sinus-rinsing.html). Tap water should never be used to clean or rinse contact lenses. Water contaminated with fuels or toxic chemicals 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, only commercially bottled water from an unopened, factory-sealed container or water that has been adequately disinfected should be used for drinking, preparing food and beverages, making ice, cooking, and carrying out oral hygiene, including brushing teeth. (See Water Disinfection for Travelers later in this chapter for proper disinfection techniques.)

Beverages made with boiled water and served steaming hot (such as tea and coffee) are generally safe to drink. When served in unopened, factory-sealed cans or bottles, carbonated beverages, commercially prepared fruit drinks, water, alcoholic beverages, and pasteurized drinks generally can be considered safe. 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 might be made from contaminated water, travelers in areas with unsafe tap water should request that beverages be served without ice.

Recreational Water

Pathogens that cause gastrointestinal, respiratory, skin, ear, eye, and neurologic illnesses can be transmitted by contaminated water during swimming, wading, or participating in other activities in saltwater or freshwater or the water in inadequately treated pools, interactive fountains (splash pads or spray parks), or hot tubs and spas. Water contaminated by sewage, animal waste, wastewater runoff, or human feces from swimmers can appear clear but still contain disease-causing pathogens or chemicals. Ingesting even small amounts of such water can cause illness. Pathogens, such as Cryptosporidium, can survive for days even in well-maintained pools and interactive fountains. Travelers should avoid ingesting any water in which they are swimming, wading, or participating in other recreational activities. They also should not swim when they have 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 enter the water to avoid contaminating it.

Maintaining proper chlorine or bromine levels and pH is necessary to prevent transmission of most infectious pathogens in water in pools and interactive fountains. Travelers should avoid pools and interactive fountains if the water is cloudy. Additional pool user tips can be found at www.cdc.gov/healthywater/pdf/swimming/resources/pool-user-tips-factsheet.pdf.

Maintaining proper chlorine or bromine levels in hot tubs and spas may be especially difficult, because the high water temperature depletes their concentration. Pseudomonas, which can cause “hot tub rash” and “swimmer’s ear,” and Legionella (see Chapter 3, Legionellosis) can multiply in hot tubs and spas in which chlorine or bromine levels are not properly maintained. Travelers should avoid hot tubs and spas where bather limits are not enforced or where the water is visibly cloudy. Additional tips can be found at www.cdc.gov/healthywater/pdf/swimming/resources/hot-tub-user-tips-factsheet.pdf. Travelers at increased risk for legionellosis, such as the elderly or those with immunocompromising conditions such as cancer or diabetes, may choose to avoid high-risk areas such hot tubs or spas (see Chapter 3, Legionellosis).

To protect their health in oceans, lakes, and rivers, travelers should try not to swim or wade 1) in water that may be contaminated with sewage, human or animal feces, or wastewater runoff; 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 Chapter 3, Schistosomiasis); 5) in water that may be contaminated with urine from animals infected with Leptospira (see Chapter 3, Leptospirosis); or 6) in warm seawater when they have cuts, abrasions, or other wounds. To help prevent a rare but fatal infection caused by Naegleria fowleri (www.cdc.gov/parasites/naegleria), a parasite found in warm freshwater around the world, travelers should prevent water from entering the nose by holding the nose shut or wearing a nose clip when swimming, diving, or participating in similar activities in warm freshwater (including lakes, rivers, ponds, hot springs, or locations with water warmed by discharge from power plants and industrial complexes), and avoid digging in or stirring up the sediment, especially during periods of high water temperature. Although Naegleria fowleri infection is typically associated with exposure to recreational water, infection has also been associated with use of tap water for sinus and nasal irrigation or rinsing.

BIBLIOGRAPHY

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