Introduction

Contaminated food and water pose an infectious disease risk to travelers due to the numerous pathogens and toxins that can be transmitted. Additional information on pathogens and toxins associated with travelers’ diarrhea and treatment options can be found in the Travelers’ Diarrhea and Post-Travel Diarrhea chapters.

Food

Travelers should select food with care. While abroad, travelers should follow food safety practices recommended in the United States. Raw food, including unpasteurized dairy products, is especially likely to be contaminated. Raw or undercooked meat, fish, shellfish, eggs, and produce can be contaminated with pathogens, and some fish harvested from tropical waters can transmit toxins that survive cooking.

In areas where hygiene and sanitation are inadequate or unknown, travelers should take additional food safety precautions, as described in Box 1.7.1.

Box 1.7.1: Safe food practices for travelers in areas with inadequate or unknown hygiene and sanitation

In restaurants, inadequate refrigeration and lack of food safety training among staff can result in transmission of pathogens or their toxins. Consumption of food and beverages obtained from street vendors increases the risk of illness. In general, fully cooked foods that are served hot and foods that travelers carefully prepare themselves are safest.

Travelers should exercise the same caution about food and water served on flights as they do for restaurants. Additionally, travelers should not bring perishable food back to their home country without refrigeration. Travelers can use insulated packaging and materials, such as frozen gel packs, to keep perishable food cold in transit. Perishable food should arrive at least as cold as it would be in a refrigerator (4°C [40°F] or below) and should not sit at room temperature for more than 2 hours. Travelers are prohibited from bringing some food items into the United States from abroad; refer to the United States Department of Agriculture’s Animal and Plant Health Inspection Service guide for travelers for more information.

Feeding infants

Breastfeeding

For infants ages <6 months, the safest way to feed is to breastfeed exclusively. Practicing careful hygiene when using a breast pump and washing pump parts using a safe source of water can reduce the risk of getting pathogens into the milk. For details, see How to Keep Your Breast Pump Kit Clean: The Essentials.

Formula

For infants who are formula-fed, parents should consider using liquid, ready-to-feed formula that is sterile. When preparing formula from commercial powder, mixing it with a safe source of water following the manufacturer’s instructions usually is sufficient. Although no powdered formula is sterile, travelers should consider packing enough for their trip because manufacturing standards vary widely around the world.

For infants ages <3 months and those with weakened immune systems, formula safety can be increased by reconstituting powder using hot water (≥70°C [≥158°F]). Boil water and wait about 5 minutes before mixing with formula powder; after mixing, wait for the prepared formula to cool before feeding the baby. Prepared formula should be used within 2 hours of preparation or refrigerated for a maximum of 24 hours. After feeding, any remaining liquid or prepared formula should be discarded. Once opened, formula containers should be stored in a cool, dry place with the lid tightly closed and used within 1 month.

For more on infant feeding hygiene:

Water

Swallowing, having contact with, or inhaling aerosols of contaminated water can transmit pathogens that cause diarrhea, vomiting, or ear, eye, skin, respiratory, or nervous system infections. Travelers should follow safe water practices recommended in the United States while abroad.

Drinking water and other beverages

In many parts of the world, particularly where water treatment, sanitation, and hygiene are inadequate, tap water can contain disease-causing agents, including bacteria, viruses, parasites, and chemical contaminants. Consequently, tap water might be unsafe for drinking, preparing food and beverages, making ice, cooking, and brushing teeth. Infants, young children, pregnant women, older people, and immunocompromised people (e.g., persons with HIV, on chemotherapy, or who take certain immune-suppressing medications) might be especially susceptible to illness.

Travelers should avoid drinking or putting tap water into their mouths unless they are reasonably certain the water is safe. Similarly, travelers should avoid ice unless they are reasonably certain it was made using safe water. Box 1.7.2 provides tips and recommendations of other safe water and beverage practices for travelers.

Box 1.7.2

Recreational water

Pathogens that cause gastrointestinal, respiratory, skin, ear, eye, and neurologic illnesses can be transmitted via contaminated recreational freshwater or marine water. Water from inadequately treated pools, hot tubs, or splash pads can also be contaminated. Recreational water contaminated by human or animal feces, sewage, or wastewater runoff can appear clear but still contain disease-causing infectious or chemical agents. Ingesting even small amounts of such water can cause illness. Infectious pathogens (e.g., Cryptosporidium) can survive for days, even in properly operated pools, splash pads, and hot tubs.

To protect themselves and other people, travelers should take health and safety precautions before, during, and after entering recreational water, as described in Box 1.7.3. Additional guidance can be found on CDC’s Healthy Swimming website.

Box 1.7.3: Healthy swimming for travelers

Maintaining proper pH and chlorine or bromine concentration is necessary for preventing transmission of most infectious pathogens in pools, splash pads, and hot tubs. If travelers would like to test recreational water before use, the CDC recommends a free chlorine concentration of 3–10 parts per million (ppm) in hot tubs (or 4–8 ppm total bromine) and 1–10 ppm free chlorine in pools and splash pads (2–10 ppm for those using chlorine stabilizer, such as cyanuric acid). Travelers can purchase test strips at most large retail companies, hardware stores, or pool supply stores. When hot tubs are not properly operated and chlorine or bromine concentrations are not adequately maintained, pathogens such as Pseudomonas, which can cause “hot tub rash” or otitis externa, and Legionella, which can cause life-threatening pneumonia, can multiply.

In freshwater recreational areas, there are many naturally occurring pathogens that can cause disease. Naegleria fowleri is a parasite found around the world in warm freshwater, including lakes, rivers, ponds, hot springs, and locations with water warmed by discharge from power plants and industrial complexes. Naegleria fowleri has also been found in inadequately chlorinated water, including in pools, splash pads, and a surf venue. People become infected when water containing Naegleria fowleri goes up their nose, usually while swimming. Healthcare professionals should also inform travelers that Naegleria fowleri infection has been linked to use of contaminated tap water for sinus or nasal irrigation. Even though Naegleria fowleri infection is rare, it is almost always fatal.

In seawater or brackish water, pathogens such as Leptospira and Vibrio vulnificus can infect people through open wounds, potentially causing serious and life-threatening disease. People with underlying health conditions, such as liver disease, cancer, diabetes, and immunocompromising conditions, are at higher risk of V. vulnificus wound infection.

Handwashing

Travelers should follow recommended handwashing practices by washing their hands with soap and water before preparing or eating food, after using the bathroom or changing diapers, before and after caring for someone who is ill, and after contact with animals or animal environments. When soap and water are not available, travelers should use an alcohol-based hand sanitizer containing ≥60% alcohol and then wash hands with soap and water when possible. Hand sanitizer is not as effective as handwashing for removing some pathogens, like Cryptosporidium or norovirus, and does not work well when hands are visibly dirty or greasy.

Acknowledgements

The following authors contributed to the previous version of this chapter: Brigette Gleason and Patricia M. Griffin.