The risk of illness or injury increases with duration of travel, so special consideration should be given to travelers who are planning long-term visits (≥6 months is a common definition) to low- or middle-income countries, whether they are expatriates with definite plans or adventurers with open itineraries. Points to discuss in the pretravel consultation include accessing care at the destination, vaccines, infectious diseases not prevented by vaccines, injury prevention, and psychological and cultural issues that long-term travelers may encounter.
Before departure, all long-term travelers should undergo complete medical and dental examinations. For expatriates, it also may be beneficial to have a psychological evaluation, as early repatriation is often due to psychological issues that could be addressed prior to travel. Travelers should anticipate that they will need care at some point during their stay, and they should plan where they will obtain it and how they will pay for it. Those traveling for work or with an organization (such as a university, the Peace Corps, or a nongovernmental organization) may have a predetermined source of care and some may access advice from the international expatriate community. By contrast, other travelers should identify a source in advance (see Chapter 6, Obtaining Health Care Abroad). Long-term travelers should also determine if they will need supplemental travel health insurance and evacuation insurance (see Chapter 6, Travel Insurance, Travel Health Insurance & Medical Evacuation Insurance).
In some countries, travelers are likely to encounter poor-quality (substandard, falsified, counterfeit, or expired) medications. Because the pills and packaging may be nearly indistinguishable from their legitimate counterparts, travelers should bring a sufficient supply of their routine medications (such as antihypertensive or antihyperlipidemic drugs) from the United States (see Chapter 6, Perspectives : Avoiding Poorly Regulated Medicines and Medical Products during Travel). Options for obtaining sufficient medications include 1) requesting an override from the insurance company to dispense the entire quantity of medication; 2) paying out of pocket for the full amount of medication needed and then submitting to the insurance company for reimbursement; 3) refilling prescriptions during trips home; or 4) relying on friends or family members who visit to bring refilled medication supplies.
Routine vaccines, including influenza vaccine, should be updated. In addition, long-term travelers should be aware of any vaccine requirements at their destination for employment, schooling, or entry. A number of travel-related vaccines warrant consideration:
In addition to the intended destination, consider disease risk in surrounding areas, since long-term travelers may be likely to travel locally. For example, a short-term traveler to Seoul would not be considered at risk for Japanese encephalitis, but an expatriate living in Seoul may have opportunities to visit the Korean countryside or other areas in Asia where he or she could be exposed. Similarly, yellow fever vaccination needs consideration as the location of posting may not be in an endemic area, but the traveler may journey to these areas when posted abroad.
Data suggest that the incidence of malaria increases and the use of preventive measures decreases with increasing length of stay. For instance, malaria incidence in British travelers returning from West Africa after a stay of 6–12 months was 80 times that of the incidence in travelers who had stayed only 1 week. Among expatriate corporate employees in Ghana, adherence to malaria prophylaxis deteriorated with increasing duration of stay, and all those who had been on the site for >1 year had abandoned prophylaxis. About half of the cohort used insect repellent only intermittently, and more than one-third never used repellent. Even though most British expatriates from the UK Foreign and Commonwealth Office had good knowledge about malaria and its prevention strategies, they adhered to malaria prophylaxis <25% of the time; only 25% reported rigorous compliance, and 13% reported having contracted malaria. A recent GeoSentinel Global Surveillance Network analysis found that Plasmodium falciparum malaria was the most frequent diagnosis among ill returned expatriate workers, occurring in 6%, and was most commonly acquired in sub-Saharan Africa. Given the high relative risk of malaria for travelers in Africa, these data on long-term travelers and expatriates highlight worrisome risks and practices.
A traveler residing in an area of continuous malaria transmission should continue to use malaria prophylaxis for the entire stay. It is important to reassure the traveler that the drugs are safe and effective. Doxycycline has been well-tolerated for long-term malaria prophylaxis in the military, and CDC has no recommended limits on its duration of use for malaria prophylaxis. Peace Corps volunteers frequently use mefloquine during prolonged stays, with a discontinuation rate of 0.9%. Mefloquine may be appropriate for long-term prophylaxis in chloroquine-resistant areas because of its convenient weekly dosing, but concern has increased regarding its neuropsychiatric side-effect profile, especially with the Food and Drug Administration label indicating that neurologic side effects may persist.
Atovaquone-proguanil has shown good long-term tolerability in postmarketing surveillance, with a discontinuation rate of only 1% because of diarrhea. Peace Corps Volunteers prescribed atovaquone-proguanil adhered to prophylaxis best, when compared to those given doxycycline and mefloquine. If long-term use (>5 years) of chloroquine is planned, a baseline ophthalmic examination with biannual follow-up is recommended to screen for potential retinal toxicity.
The possibility of pregnancy requires careful consideration for travelers to areas where malaria is endemic (see Chapter 7, Pregnant Travelers). Malaria infection during pregnancy can result in severe complications to both mother and fetus. When pregnancy is anticipated, prophylaxis options may need to be adjusted. Ideally, this possibility should be explored before travel with all female long-term travelers of childbearing age. For women who are pregnant or plan to become pregnant during long-term travel, mefloquine is considered safe in all trimesters. Data from published studies in pregnant women have shown no increase in the risk of teratogenic effects or adverse pregnancy outcomes after mefloquine prophylaxis during pregnancy. Chloroquine has also been used long-term without ill effect on pregnancy. If a woman traveling long-term is taking atovaquone-proguanil, doxycycline, or primaquine, she should discontinue her medication and begin weekly mefloquine (or chloroquine in those areas where it remains efficacious), and then wait at least 3–4 weeks to conceive so that a therapeutic blood level of mefloquine can build up.
Women who become pregnant while taking antimalarial drugs do not need a therapeutic abortion but should be advised during the pretravel consultation of potential risks. The effect of atovaquone-proguanil on the fetus is unknown, but doxycycline is associated with fetal toxicity in animals and is contraindicated in pregnant women. Primaquine and tafenoquine may harm a G6PD-deficient fetus, so should not be used in pregnancy.
French service members deployed to the Central African Republic for 4 months in 2013 experienced malaria at a rate of 150 cases/1,000 person-years. A survey found that prophylaxis compliance correlated positively with use of other prophylactic measures against malaria (bed net use, insecticide on clothing, taking prophylaxis at the same time every day), correct perception of malaria risk, favorable perception of prophylaxis effectiveness, and peer-to-peer reinforcement.
For long-term travelers, the need for adjuncts to prophylaxis should be stressed, such as personal protection measures to avoid mosquito bites (see Chapter 3, Mosquitoes, Ticks & Other Arthropods). Even with urging to adhere to personal protective measures and reassurance that long-term prophylaxis is safe and effective, adherence is likely to decline over time. Consequently, the pretravel consultation for a long-term traveler to areas where malaria is present should stress the severity of the disease, its signs and symptoms, and the need to seek care immediately if they develop. Travelers could consider bringing a reliable supply of drugs to treat malaria if they are diagnosed with the disease.
Because diarrhea and gastrointestinal diseases occur commonly, long-term travelers should be educated about their management (see Chapter 2, Travelers’ Diarrhea). Measures include rehydration, use of antimotility agents, empiric antimicrobial therapy, and knowing when to seek care.
Tuberculosis risk in a traveler may rise to that of the local population if the traveler or expatriate has a longer stay and intimate contact with the local population. A baseline interferon-γ release assay or a tuberculin skin test, followed by the same test after travel, should be considered for long-term travelers. Tuberculosis screening is particularly important for health care workers or those who may be working in hospitals, refugee camps, or in prisons.
Likewise, dengue seroconversion occurred at a rate of 3.4/1,000 workers per month of stay in endemic areas. Other mosquitoborne viral illnesses (such as chikungunya and Zika) also pose potential risk, so advise long-term travelers and expatriates to protect themselves from mosquito vectors. Chapter 4 provides disease-specific information on dengue, chikungunya, and Zika virus infections.
Risk for HIV and sexually transmitted infections are increased in travelers and expatriates, and the consistent use of condoms in expatriates is low (approximately 20%). Long-term travelers should be educated about the risk of HIV and sexually transmitted infections at their destination, as well as preventive measures. The potential for occupational exposure to HIV is important to consider in health care workers; postexposure prophylaxis with antiretroviral therapy and risk avoidance should be included in the pretravel consultation (see the Health Care Workers section in this chapter).
Transfusion is a potential source of hepatitis C infection in expatriates. The risk of hepatitis E, spread by the fecal–oral route, is highest in Asia, although it has been transmitted in many different tropical locations. Pregnant women are at highest risk of fulminant disease.
Other infections vary with location and include giardiasis, amebiasis, strongyloidiasis, schistosomiasis, cutaneous leishmaniasis, and filariasis. Travelers can prevent Strongyloides stercoralis infections by not walking barefoot through soil and schistosomiasis by not swimming or wading in fresh water. This latter risk is difficult to communicate to long-term travelers who, for example, may be living in sub-Saharan Africa and who look forward to river rafting or vacationing at a lake. The risks of strongyloidiasis and schistosomiasis increase with long-term travel, so screening on return (and also during long-term expatriate assignments for those with access to health care) should also be discussed. Cutaneous leishmaniasis and filariasis should be reviewed if a traveler has the potential geographic exposure risk. Compared with short-term travelers, long-term travelers experience more chronic diarrhea and postinfectious irritable bowel syndrome (possibly because some become less adherent to food and water precautions over time) and should be advised to continue food and water precautions in order to reduce the risk for these conditions (see Chapter 2, Food & Water Precautions).
Since injuries are the leading cause of preventable death in travelers, educate long-term travelers about safety (see Chapter 8, Road & Traffic Safety). Stress the importance of road and vehicle safety and emphasize that travelers should choose the safest vehicle options available. Roads are often poorly constructed and maintained, traffic laws may not be enforced, vehicles may not have seatbelts or be properly maintained, and drivers may be reckless and poorly trained. See Chapter 3, Injury & Trauma, for strategies to reduce the risk of traffic and other injuries.
Culture shock and the stress of long-term travel can trigger or exacerbate psychiatric reactions. A long-term traveler should be assessed for preexisting psychiatric diagnosis, depressed mood, recent major life stressors, and use of medications that may have psychiatric effects. Any of these conditions suggest a need for further screening. All long-term travelers should be warned about illicit drug use and urged to take care of their physical and mental health by exercising regularly and eating healthfully. They should be able to recognize signs of anxiety and depression and have a plan for coping with them. Having photographs or other mementos of friends and family at hand and staying in close contact with loved ones at home can alleviate the stress of long-term travel. For more information, see Chapter 3, Mental Health.
Offering pretravel care to long-term travelers, especially those with no itinerary or those who present with only vague travel plans, presents unique challenges. These travelers benefit from broad immunization coverage for all potential exposures to vaccine-preventable diseases. Because their plans are unclear, these travelers must understand that they may need to diagnose and treat themselves for common ailments, including travelers’ diarrhea, upper respiratory tract infections, urinary tract infections, vaginitis, skin disorders, and musculoskeletal problems. For travelers such as backpackers who may go in and out of malarious areas, a sensible approach is to provide a supply of atovaquone-proguanil with instructions on how to take it when they do visit risk areas. In addition to strategies to prevent health problems and injuries during their long sojourns, traveler education is imperative regarding health resources, signs and symptoms that require urgent medical evaluation, and medical evacuation.
After returning to their country of origin, long-term travelers (expatriate workers, Peace Corps volunteers, or highly adventurous travelers) will ideally have a thorough medical interview to assess potential infectious exposures. A careful itinerary-specific history with detailed questioning about potential high-risk exposures including food, water, animal, and human contact is the foundation of the posttravel evaluation. Returning travelers should have a physical examination focused on specific signs and symptoms and a selected array of tests. These tests include a complete blood count with differential, hepatic transaminases, and serologic markers depending on types of exposure (but most importantly for strongyloidiasis and schistosomiasis). Serologic testing can detect subclinical infections and determine whether seroconversion to the more common pathogens (where treatment would be advised) has occurred (see Chapter 11, Screening Asymptomatic Returned Travelers). A benefit of the posttravel evaluation is preventive counseling for potential future travel.
Lin H. Chen, Davidson H. Hamer