TRAVEL AND HEALTH OVERVIEW

More individuals are traveling internationally now than ever before. International travel can lead to wonderful new experiences and lasting memories. Unfortunately, travel can also lead to health problems that range in severity from unpleasant to life threatening.

Travel-related health problems arise from a variety of factors, including exposure to infectious organisms, the use of certain types of transportation, and participation in certain activities, such as diving and high-altitude hiking during travel. Travel-related health problems can also arise when a preexisting medical condition worsens during travel.

Fortunately, most travel-related health problems can be prevented with a combination of pre-travel planning, immunizations, and safety precautions during travel. If you are planning travel outside of your home country, consult your healthcare provider at least one month prior to traveling. The provider can give immunizations, travel medications, and tips for staying healthy during the trip, or may recommend a specialized travel medicine provider for some or all of these immunizations, medications, and advice.

A general overview of advice related to travel and health will be reviewed here. Immunizations for travel are discussed separately. (See "Patient information: Immunizations for travel".)

PRE-TRAVEL EVALUATION

Individuals planning international travel should visit their healthcare provider and/or specialized travel medicine clinic. The visit also provides an opportunity to discuss the specific details of travel. This information is necessary to formulate individualized travel-related medical advice:

• Duration of travel
• Season of travel
• Countries and regions that will be visited
• Planned activities during travel
• Place of residence during travel (for example, a modern hotel, rural home, campground)

TRAVEL-RELATED MEDICAL ADVICE

Once a clinician has assessed your travel plans and overall health, he or she can provide information about the health risks that could be encountered and can give advice for minimizing these risks.

Vaccines — Vaccines recommended for travel are discussed in detail in a separate topic review. (See "Patient information: Immunizations for travel".)

Food and water precautions — Several infections can be acquired by ingesting contaminated food and water, including infectious diarrhea (travelers' diarrhea), hepatitis A, and, less commonly, trichinellosis. (See "Patient information: Food poisoning (food-borne illness)".)

In areas where sanitation and personal hygiene are poor, food and water precautions are essential for reducing the risk of these infections. These precautions will be most effective when they are used on a daily basis.

Tap water that looks safe to drink can carry infection-causing organisms, but boiling the water for three minutes, followed by cooling, can kill these organisms. Alternately, two drops of 5 percent bleach or five drops of tincture of iodine in 2 quarts of water kills most organisms within 30 minutes.

Travelers can reduce the risk of infection by using the following precautions:

• Do not drink or brush the teeth with unboiled tap water
• Do not drink beverages that contain ice made from unboiled tap water
• Drink only boiled tap water, drinks made from boiled tap water, carbonated beverages, beer, and wine
• Be wary of locally bottled water, because safety and bottling conditions might not be adequate. Other drinks are probably safer.

Food can also contain infection-causing organisms. Reduce the risk of infection by following several food precautions:

• Do not eat unpeeled fruit. Peel any fruit yourself before eating it.
• Do not eat raw vegetables
• Do not eat or drink unpasteurized ("raw") dairy products
• Do not eat raw or rare meat, fish, or shellfish (including ceviche)

Insect and tick bites — In certain areas of the world, insects (mosquitoes, flies, fleas, bugs, and lice) and arthropods (ticks and mites) can transmit a number of potentially serious infections, including malaria.

Before you leave, you should buy insect repellants to bring with you. The best ones are DEET, permethrin, and picaridin; you can find these at sporting goods stores in the United States.

You can lower your risk of infection by following these precautions every day while you are traveling:

• Whenever possible, avoid insect-infested and tick/mite-infested areas
• Wear protective clothing, including long-sleeved shirts and pants; if you can, treat your clothing with permethrin
• Use insect and tick/mite repellents that contain DEET or picaridin
• Use mosquito netting over your bed; treat the netting with permethrin
• Check your skin regularly and remove any insects or ticks/mites
• Whenever possible, minimize time spent outdoors after dark

Malaria prevention — Malaria is a serious infection that is spread by the bite of an infected mosquito. The above suggestions can reduce the risk of being bitten. Antimalaria medications are also recommended to people who travel to certain areas. These medications should be taken exactly as prescribed, starting before traveling to affected areas and continuing for up to four weeks after returning. The dosage and schedule depends upon which antimalarial medication is used.

Infection-causing organisms — Open water, soil, and sand can harbor infection-causing organisms in some areas of the world.

In countries where schistosomiasis (a water-borne parasitic infection) is common, travelers should avoid swimming in fresh water. Even brief exposure to infested water (for example, during rafting) can result in infection. In contrast, swimming in salt water or chlorinated water in these countries is safe.

When you are traveling, don't walk barefoot on soil or sand that could be contaminated with dog or human feces. This can lead to hookworm or strongyloidiasis infections (worms that can penetrate the skin and cause itching, stomach symptoms, and other problems).

Sexually transmitted diseases — Studies of travelers' behaviors indicate that many people are more sexually active during travels. The hepatitis B virus, the human immunodeficiency virus (HIV, the virus that causes AIDS), as well as more common infections, such as gonorrhea, chlamydia, and syphilis, are all transmitted by sexual contact, and are often more prevalent in developing countries.

Avoiding sexual contact eliminates the risk of acquiring sexually transmitted disease during travel. Use of barrier methods, such as a latex condom or diaphragm, reduces the risk of disease transmission, although they do not eliminate the risk. (See "Patient information: Hepatitis B" and "Patient information: Symptoms of HIV infection".)

Personal medications — Medications available in the United States may not be available in other countries. Therefore, travelers who must take medication regularly should bring enough medication with them for the duration of their trip. Medications should be taken on the plane in a purse or other carry-on bag, rather than packed in luggage, to avoid loss or theft. Travelers who require syringes to administer medication should carry those syringes along with a letter from a healthcare provider documenting a medical need for the syringes.

Avoiding accidents — Accidents, especially motor vehicle accidents, account for about 25 percent of deaths in American travelers. The risk of accidents, injury, and death may be reduced by taking several precautions:

• Avoid driving at night, which can minimize exposure to alcohol-impaired drivers
• Familiarize yourself with the local driving conditions
• Wear a seat belt at all times
• Avoid drinking alcoholic beverages and driving
• If using motorized cycles, wear helmets and be especially cautious

Tuberculosis testing — Travelers who are planning travel to regions where tuberculosis (TB) is common may be advised to have a tuberculosis skin test before and after their trip. (See "Patient information: Tuberculosis".)

Anyone who is exposed to or becomes infected with tuberculosis will need treatment if skin testing becomes positive. The risk is higher for traveling healthcare workers compared with other types of travelers. However, the risk of tuberculosis exposure may be reduced by avoiding close contact with people who are coughing or sneezing, although this is not always possible.

TRANSPORTATION ADVICE

Travel-related health problems can be related to the type of transportation used during travel.

Ships — The Centers for Disease Control and Prevention (CDC) inspects all cruise ships that dock at ports in the United States. This ensures that ships meet strict sanitation guidelines. Information about the past record of a specific cruise ship can be obtained from travel agents, state health departments, or the CDC (www.cdc.gov/travel/cruiships.htm).

Air travel — Air travel can be associated with several problems.

Lower-oxygen environment — Aircraft that fly at low altitudes may not pressurize the cabin. Jet aircraft that fly at higher altitudes pressurize the cabin, although the pressure is less than that on the ground. Under both conditions, the air in the cabin contains less oxygen than the air on the ground, which reduces the amount of oxygen in the blood.

Exposure to a lower-oxygen environment can lead to problems in people with certain medical conditions, including chronic obstructive pulmonary disease (COPD) and some heart conditions. A patient may feel short of breath, which could require the use of supplemental oxygen. (See "Patient information: Supplemental oxygen on commercial airlines".)

A lower-oxygen environment can also be a problem for people who experience a heart attack while abroad. Such individuals can usually make a return flight home two to three weeks after the heart attack, as long as a healthcare provider accompanies them.

Ear and sinus symptoms — The change in air pressure during flight may cause ear and sinus symptoms, especially for travelers with upper respiratory tract infections. These symptoms may include difficulty hearing and pain in the ears or sinuses. In most individuals, the symptoms can be prevented by taking an oral (pseudoephedrine) or nasal (oxymetazoline) spray, decongestants, or antihistamines (diphenhydramine).

Blood clots — Sitting for prolonged periods during air travel causes blood to pool in the legs, which can increase the risk of forming blood clots in the legs, especially in individuals who have clotting or vein disorders. People with these conditions may be advised to take certain medications, to stretch frequently, and/or to wear compression stockings during long flights to reduce the risk of blood clots. (See "Patient information: Deep vein thrombosis (DVT)".)

All travelers should consider the following recommendations for flights longer than six to eight hours (table 1).

Motion sickness — Individuals who suffer with motion sickness can take a medication before a flight (or before sailing if on a cruise ship) to prevent this condition. Over-the-counter drugs work for most individuals; a clinician can recommend a prescription-strength medication if needed.

Jet lag — Travelers who cross several time zones may experience jet lag. In general, it takes longer to recover from jet lag after flying west to east than east to west. Adult travelers crossing five or more time zones are likely to benefit from melatonin, especially if they have experienced jet lag on previous journeys. It is also reasonable for people making such a journey for the first time to take melatonin, if jet lag might seriously interfere with work or leisure activities at their destination. Travelers crossing two to four time zones may also try melatonin.

The recommended dose of melatonin is 2 or 3 mg about 30 minutes before bedtime on the day of travel and for up to four days after arrival; a dose of 0.5 mg has less effect on sleep but can help the person to adapt to the new time zone. A test dose taken at home before travel may help determine which dose is most appropriate. Alcohol should be avoided with melatonin.

TRAVELING WITH MEDICAL CONDITIONS

Additional travel considerations are necessary for pregnant women, people with HIV infection, and people with diabetes. More information about traveling with a medical condition is available on the CDC Web site, www.cdc.gov/travel/spec_needs.htm.

Pregnant women — Most women can travel safely during pregnancy, although the type of travel and possible health hazards must be considered on an individual basis. Air travel does not have any known negative effects on a pregnant woman or the baby. Women who have had complicated pregnancies in the past (premature delivery, late-term miscarriage, high blood pressure, or other complications) should avoid extensive travel during their current pregnancy. In addition, pregnant women should be sure to follow precautions to avoid blood clots since pregnancy increases the risk of clotting. (See 'Blood clots' above.)

Pregnant women may not be able to receive certain immunizations and antibiotics. Pregnant women who travel to regions where malaria is common need to understand that exposure to malaria increases her and her baby's risk of complications. Not all antimalarial medications have been studied to determine their safety in pregnancy. Expert advice about the wisdom of traveling in regions where malaria is present, the safety of various antimalarial drugs, and the risks of malaria in pregnancy should be considered prior to travel. (See "Patient information: Avoiding infections in pregnancy".)

The Center for Disease Control and Prevention provides reliable information about travel during pregnancy, available online at www.cdc.gov/travel/yellowBookCh9-PregnancyTraveling.aspx.

HIV infection — HIV infection can pose several problems during travel.

• People with HIV may not be allowed to enter some countries; check with consular offices when planning international travel. In addition, people with HIV should try to locate adequate medical facilities in the planned destinations.
• People with HIV will not be able to receive certain travel immunizations. HIV-infected travelers should carry all necessary medications with them.

Diabetes — Travelers with diabetes who take insulin should seek expert advice on modifying timing of insulin doses if traveling over many time zones.

Syringes, blood glucose testing supplies, insulin and glucagon or oral medications, and snacks should be packed in a carry-on bag and available at all times. People who require syringes should carry a note from their healthcare provider, explaining the need for diabetes-related supplies. In addition, the person should wear a necklace or bracelet that lists their medical condition and a phone number to locate additional emergency contact information.

SPECIAL ACTIVITIES

A few activities have specific recommendations to ensure the safety of the traveler during and after the activity.

Scuba diving — Individuals who scuba dive while traveling should wait 12 to 48 hours (depending on the length of dives) before boarding a jet airplane. This measure is important for avoiding decompression sickness (also called "the bends").

High-altitude exposure — Individuals who will be traveling to mountainous or other high-altitude regions should talk with their healthcare provider about preventing and treating high-altitude illnesses. These illnesses include mountain sickness, high-altitude pulmonary edema, and high-altitude cerebral edema. (See "Patient information: High altitude illness (including mountain sickness)".)

Wilderness travel — Individuals who plan travel to remote areas that lack medical facilities should discuss precautionary measures with their clinician, especially if they will be exposed to extreme climates or exercise-related stress (for example, mountain climbing or long-distance bicycle tours).

RETURNING TRAVELERS

Anyone who experiences symptoms of fever, diarrhea, or rash following their return from international travel should consult their healthcare provider immediately.

WHERE TO GET MORE INFORMATION

Your healthcare provider is the best source of information for questions and concerns related to your medical problem.

This article will be updated as needed every four months on our Web site (www.uptodate.com/patients).

Related topics for patients, as well as selected articles written for healthcare professionals, are also available. Some of the most relevant are listed below.

Patient level information

Patient information: Immunizations for travel
Patient information: Food poisoning (food-borne illness)
Patient information: Hepatitis B
Patient information: Symptoms of HIV infection
Patient information: Tuberculosis
Patient information: Supplemental oxygen on commercial airlines
Patient information: Deep vein thrombosis (DVT)
Patient information: Avoiding infections in pregnancy
Patient information: High altitude illness (including mountain sickness)

Professional level information

Clinical manifestations of malaria
Diseases potentially acquired by travel to Central and South America
Diseases potentially acquired by travel to East Asia
Diseases potentially acquired by travel to Southeast Asia
Diseases potentially acquired by travel to sub-Saharan Africa
Epidemiology, prevention and control of malaria in endemic areas
Immunizations for travel
Management of Crotalinae (rattlesnake, water moccasin [cottonmouth], or copperhead) bites in the United States
Management of Elapidae (coral snake) bites in the United States
Pathogenesis of malaria
Potential health hazards in travelers to Australia, New Zealand, and the southwestern Pacific (Oceania)
Prevention of malaria infection in travelers
Principles of snake bite management worldwide
Rabies immune globulin and vaccine
Travel advice
Travelers' diarrhea

The following organizations also provide reliable health information:

• Centers for Disease Control and Prevention (CDC) travel page

      (www.cdc.gov/travel/)

      Toll-free: (800) 232-4636

• World Health Organization page on international travel and health

      (www.who.int/ith/)

• National Library of Medicine

      (www.nlm.nih.gov/medlineplus/healthtopics.html)

• Infectious Diseases Society of America

      (www.idsociety.org)

• American Society of Tropical Medicine and Hygiene - clinical consultative service in Tropical Medicine, Medical Parasitology and Travelers' Health

      (www.astmh.org/source/ClinicalDirectory/)

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