Travel advice

INTRODUCTION — Medical advice for travelers should include evaluation of the risk for adverse outcomes depending on the traveler's medical conditions, the itinerary, anticipated activities, and potential exposures [1]. Risks of illness associated with travel include:

●Development of illness while in transit [2]

●Exposure to infections endemic to areas visited

●Environmental exposures associated with travel

The pretravel evaluation should provide advice about the risks for vaccine-preventable infections, the appropriate immunizations, and prophylaxis against travelers' diarrhea and malaria [3]. It should also include advice about behavioral precautions and environmental exposures.

Many travelers to high-risk regions are not aware of their need for pre-travel health advice, and many clinicians are not aware of the most appropriate advice regarding preventive measures [4,5]. In addition, travelers returning to their country of origin to visit friends and relatives are less likely to seek advice since they may not realize they are at risk for illness associated with travel [6-9]. As a result, preventable systemic illnesses such as malaria and typhoid fever occur more commonly in this risk group than among other travelers [10].

Issues related to advice for travelers will be reviewed here. Further information can also be obtained at the United States Centers for Disease Control and Prevention (CDC) website. This site includes an online version of Health Information for International Travel and updates on travel-related infections [11]. Guidance may also be found via GlobalTravEpiNet, which has web-based tools for providers and patients based on CDC recommendations. Websites with travel information maintained in the United Kingdom include the United Kingdom National Travel Health Network and Centre (NaTHNaC), and the related site Travel Health Pro.

Issues related to travel advice for immunocompromised hosts are discussed in detail separately. (See "Travel advice for immunocompromised hosts".)

TRAVEL-RELATED INFECTIONS — Travel-associated infections may be acquired via enteral, respiratory, vector-borne, and/or sexual exposures [1,12,13]. According to GeoSentinel (a network of clinical sites that perform surveillance of illnesses among ill travelers), the most common syndromic diagnoses include gastrointestinal, febrile, and dermatologic illnesses [14]. Asia and sub-Saharan Africa were the most common regions where illnesses were acquired (32 and 25 percent). Approximately 40 percent of ill travelers reported pretravel medical visits. Travelers visiting friends and relatives in their country of origin had a disproportionately high burden of serious febrile illness and very low rate of advice prior to travel.

In addition to variability of health risks according to destination, travel duration, type of travel, activities undertaken, specific traveler characteristics, and other factors influence the chances of presenting for healthcare with various infections. For example, women are proportionately more likely than men to present after travel with diarrhea, upper respiratory tract infections, urinary tract infections, or adverse reactions to medication, whereas they are proportionately less likely to present following travel with vector-borne diseases or sexually transmitted infections [15].

PRETRAVEL EVALUATION — Medical consultation should be obtained at least one month before travel to allow time for thorough evaluation and for immunizations (see "Immunizations for travel"). A general medical history should include:

●Pertinent underlying medical conditions (including immune compromise due to transplantation or HIV infection) and current medications [16]

●History of allergies to antimicrobial agents or to components of vaccines (eggs, gelatin)

●Whether the patient is pregnant

Understanding the itinerary, duration, and purpose of a trip can help to estimate the risks of exposure to endemic diseases. Stays at major resorts and first-class hotels are associated with less risk than visits to less-established facilities or rural dwellings or encampments.

Patients should take sufficient supplies of current medications; equivalent drugs may not be available in travel destinations. Medications required for daily use should be carried and not left in baggage that might become lost.

Patients should also consider travelers insurance, including evacuation insurance.

TRAVEL ADVICE

Vaccinations and prophylaxis

Immunizations — Immunization for travelers can be divided into three categories: routine prevention, required for travel, and recommended based on the risk of exposure to vaccine-preventable diseases. These issues are discussed in detail separately. (See "Immunizations for travel".)

Malaria prevention — Issues related to malaria prevention include mosquito avoidance and chemoprophylaxis. These are discussed in detail separately. (See "Prevention of malaria infection in travelers".)

Travelers' diarrhea — Risk of travelers' diarrhea should be reviewed and medication offered for presumptive self-treatment if indicated [17]. This is discussed in detail separately. (See "Travelers' diarrhea: Treatment and prevention".)

Behavioral precautions

Food and water — It is prudent to be careful of food and water in areas where sanitation and personal hygiene may be poor. Hands should always be washed before eating. Infections transmissible by contaminated food and water include travelers' diarrhea and hepatitis A and E. Transmission of parasitic infections can also occur.

In such circumstances, travelers should avoid consuming tap water, ice made from tap water, and raw foods rinsed with tap water. Chlorination kills most bacterial and viral pathogens, but protozoal cysts of Giardia lamblia and Entamoeba histolytica and oocysts of Cryptosporidium may survive.

Boiled, treated, or bottled water may be consumed. Carbonated beverages, beer, wine, and drinks made with boiled water are safe. Produce that is peeled by the traveler may be eaten. Food should be eaten well-cooked and while still hot. Unpasteurized dairy products and undercooked fish or meat should be avoided.

Vector avoidance — Travelers to areas with malaria, dengue, chikungunya, Zika, and other vector-borne diseases should receive instructions regarding methods to prevent bites from mosquitoes. These measures are also generally effective for reducing risks of bites from sandflies, ticks, and other insects. Measures include:

●Avoiding outdoor exposure during mosquito feeding time (for malaria, Japanese encephalitis, and West Nile virus, this is between dusk and dawn; for dengue, chikungunya, Zika, and yellow fever, this is during the daytime)

●Wearing clothing that reduces the amount of exposed skin

●Using an insect repellant

●Treating fabrics (including clothes) with insecticides

Other factors and details of appropriate repellants and insecticides are discussed separately. (See "Prevention of arthropod and insect bites: Repellents and other measures".)

Respiratory infections — Respiratory infections such as influenza, severe acute respiratory syndrome coronavirus 2, and other respiratory viruses are common in travelers. The importance of good hand hygiene should be emphasized and appropriate vaccinations considered. Tuberculosis is also an important respiratory pathogen among travelers to endemic areas. (See "Epidemiology of tuberculosis".)

Swimming and beaches — Swimming in fresh water should be avoided in areas where schistosomiasis is prevalent. Even short exposures to infested water during rafting or swimming are sufficient for transmission [18-20]. Swimming in chlorinated or salt water is safe. Rafting and other water-related activities, including exposure to flood waters, can also result in exposure to leptospirosis.

Travelers also should be cautioned about the risks of walking barefoot or in loose-fitting footwear on beaches, on soil, or in water that may be contaminated with human or canine feces. Such exposure may lead to contact with hookworm or Strongyloides larvae. Acquisition of the larvae can cause cutaneous larva migrans, hookworm, or strongyloidiasis. (See "Hookworm-related cutaneous larva migrans" and "Hookworm infection" and "Strongyloidiasis".)

Travelers should also wear sunglasses and sun blocking agents with ultraviolet A and B protection.

Animal avoidance — Travelers should be warned against approaching animals and should be advised regarding potential risks from animal bites and scratches, including rabies [21-23]. (See "Clinical manifestations and diagnosis of rabies" and "Immunizations for travel".)

For patients travelling to areas where rabies is endemic, counseling should include the following [24]:

●Dogs are the main source of rabies among travelers. Activities that confer risk for rabies infection include camping, spelunking, and working with animals (veterinarians, animal handlers, field biologists)

●Children should be supervised closely around animals.

●Individuals with a bite or scratch should washed the area immediately with soap and water, then seek immediate medical care including postexposure vaccination as soon as possible (even if previously vaccinated). If vaccination is not locally available, be prepared to travel to another area or return home to receive treatment.

Injury — Unintentional injuries, especially road traffic accidents, are estimated to cause nearly 25 percent of death among travelers [25]. Travelers should be reminded to diminish risks by avoiding driving at night, using seat belts, becoming familiar with local driving conditions, and avoiding alcohol consumption while driving.

Sexually transmitted diseases — Travelers should be cautioned about sexual contacts, especially in areas with high prevalence of HIV, hepatitis B, and other sexually transmitted infections and should be advised to use condoms [26-29].

TRANSPORTATION

Air travel — Prolonged immobilization during flight may cause venous thrombosis in individuals with preexisting thrombotic or venous disease. (See "Overview of the causes of venous thrombosis", section on 'Extended travel' and "Assessment of adult patients for air travel", section on 'Venous thromboembolism'.)

Jet aircraft are not pressurized to sea level, so passengers are exposed to high-altitude environments, resulting in diminished arterial oxygen tension (PaO₂) [30,31]. For patients with impaired cardiopulmonary function or other health problems (eg, sickle cell disease), supplemental oxygen may be needed. (See "Evaluation of patients for supplemental oxygen during air travel".)

In travelers with upper respiratory tract infections, differential air pressures between blocked eustachian tubes or sinuses and the cabin may develop on ascent or descent and impair hearing or cause pain in the ears or sinuses. Symptoms can be relieved by the use of decongestants. (See "Ear barotrauma".)

Jet lag may result when travel extends over several time zones. Issues related to the prevention and treatment of jet lag are discussed separately. (See "Jet lag".)

Cruise ships — Cruise ships that dock at ports in the United States are inspected for sanitation by United States Centers for Disease Control and Prevention (CDC) officials to minimize the potential for gastrointestinal disease outbreaks on board. Travelers may obtain information on whether specific cruise ships meet sanitation standards from travel agents, state health departments, or the CDC website.

SPECIFIC MEDICAL CONDITIONS — Several conditions warrant special consideration before travel.

Pregnancy — Air travel in pregnancy is discussed in detail separately. (See "Prenatal care: Patient education, health promotion, and safety of commonly used drugs", section on 'Airline travel'.)

Issues related to pretravel immunizations in pregnancy are discussed separately. (See "Immunizations for travel".)

Careful attention to the need for malaria prophylaxis is important since malaria infection can be a life-threatening infection for both mother and fetus [32-35]. (See "Prevention of malaria infection in travelers", section on 'Pregnant patients'.)

Zika virus infection has also been associated with congenital microcephaly and fetal losses among women infected during pregnancy; it has been advised that pregnant women consider postponing travel to any area where Zika virus transmission is ongoing. (See "Zika virus infection: An overview".)

For presumptive self-treatment of severe travelers' diarrhea in pregnancy, azithromycin is the preferred antibiotic choice. A third-generation cephalosporin is an acceptable alternative.

HIV infection — There are several issues related to international travel by HIV-infected patients to consider. If possible, competent medical facilities should be identified in destination countries, and all medications should be carried with the traveler. Some countries will not allow entry to individuals with HIV or those found to be carrying antiretroviral medications; consular offices for countries should be checked prior to travel. Issues related to travel immunizations for HIV patients are discussed separately. (See "Immunizations for travel".)

In addition to routine causes of opportunistic infection, infectious risks related to travel include parasitic opportunistic infections (eg, Cyclospora, cryptosporidiosis, Isospora belli, and visceral leishmaniasis) and fungal infections (eg, cryptococcosis and histoplasmosis). (See "Cyclospora infection" and "Epidemiology, clinical manifestations, and diagnosis of Cystoisospora (Isospora) infections" and "Visceral leishmaniasis: Clinical manifestations and diagnosis", section on 'HIV-VL coinfection'.)

Diabetes mellitus — East–west travel across times zones often requires adjustments in insulin dosing. Travelers need to carry their syringes, medications, and snacks in carry-on bags.

ENVIRONMENTAL EXPOSURES — Travelers may plan specific activities during travel that raise additional issues for evaluation and counseling.

Diving — Scuba divers should wait 12 to 48 hours before boarding a commercial aircraft to avoid developing decompression sickness, commonly known as the bends [36]. There are a number of issues that merit consideration for travelers planning to engage in underwater diving; these are discussed separately [36]. (See "Complications of SCUBA diving" and "Air embolism".)

High altitude — Specific pretravel advice and medication related to altitude illnesses, including acute mountain sickness, high-altitude pulmonary edema, and high-altitude cerebral edema, should be provided for travelers to high altitudes [37]. (See "High-altitude illness: Physiology, risk factors, and general prevention".)

Patients with cardiac disease should be evaluated and counseled as outlined separately. (See "Approach to patients with heart disease who wish to travel by air or to high altitude".)

Wilderness travel — For those planning travel in outlying areas away from medical access and who are subject to potential environmental and exercise-related stresses, specific advice and planning should be offered based upon the traveler's health and planned activities [38-41].

SOCIETY GUIDELINE LINKS — Links to society and government-sponsored guidelines from selected countries and regions around the world are provided separately. (See "Society guideline links: Travel medicine".)

INFORMATION FOR PATIENTS — UpToDate offers two types of patient education materials, "The Basics" and "Beyond the Basics." The Basics patient education pieces are written in plain language, at the 5^th to 6^th grade reading level, and they answer the four or five key questions a patient might have about a given condition. These articles are best for patients who want a general overview and who prefer short, easy-to-read materials. Beyond the Basics patient education pieces are longer, more sophisticated, and more detailed. These articles are written at the 10^th to 12^th grade reading level and are best for patients who want in-depth information and are comfortable with some medical jargon.

Here are the patient education articles that are relevant to this topic. We encourage you to print or email these topics to your patients. (You can also locate patient education articles on a variety of subjects by searching on "patient info" and the keyword(s) of interest.)

●Basics topics (see "Patient education: Staying healthy when you travel (The Basics)" and "Patient education: Vaccines for travel (The Basics)" and "Patient education: Travelers' diarrhea (The Basics)")

●Beyond the Basics topics (see "Patient education: General travel advice (Beyond the Basics)")

SUMMARY

●Risks of illness associated with travel include exposure to endemic infections, development of illness while in transit, and environmental exposures associated with travel. Medical advice for travelers should include evaluation of the risk for adverse outcomes depending on the traveler's medical conditions, the itinerary, anticipated activities, and potential exposures. (See 'Introduction' above.)

●The pretravel evaluation should include underlying medical conditions, current medications, and history of allergy to antimicrobial agents or vaccine components. Issues related to specific conditions including pregnancy, HIV infection, and diabetes warrant special consideration. (See 'Pretravel evaluation' above and 'Specific medical conditions' above.)

●The pretravel evaluation should provide advice about the risks for vaccine-preventable infections, appropriate immunizations, and prevention of travelers' diarrhea and malaria (if warranted). It should also include behavioral precautions including issues related to food and water in areas with poor sanitation, caution regarding swimming and beaches in areas with high risk for parasitic infection, measures to reduce risk of traffic accidents, and caution regarding sexually transmitted infections. (See 'Travel advice' above.)

●Air travel is associated with risks including venous thrombosis, diminished oxygen tension, changes in cabin pressure affecting ears or sinuses, and jet lag. Cruise ship travel has been associated with gastrointestinal disease outbreaks. Environmental exposures warranting additional counseling include diving and high-altitude travel. (See 'Transportation' above and 'Environmental exposures' above.)