9. Health Care of the International Traveler - David N. Spees
Health care of the international traveler starts with pretravel education and prevention and ends with posttravel evaluation for exposures to diseases not normally encountered in the country of origin.
The goals of the pretravel visit are (1) education of the traveler, (2) assessment of the risk of exposure to preventable diseases, and (3) provision of preventive and prophylactic care. The travel history is the most important component for assessing risk. Critical elements include the type and purpose of the trip, departure date, itinerary, duration and degree of risk, climate and altitude, mode of travel, and place of sleep. This additional information complements the standard medical history and evaluation. Figure 9.1 is a sample history form.
The risk of encountering health problems during travel correlates directly with the type of trip. Exposure increases in about the following order of trip type: Cruises are the least hazardous, as passengers spend the nights aboard, limiting exposure to indigenous diseases and arthropods. Pleasure and adventure seekers require special attention depending on their definition of "pleasure" or "adventure"; some are only sightseers, whereas others are seeking sexual encounters. Business trips can be lonely and prolonged. This isolation from family and familiar mores can result in behaviors or pleasures not normally risked. The most hazardous common trip for travelers is a safari, typically to East Africa. Most safaris are physically comfortable, but exposure to insect-borne disease, local water, and native food is frequent. Of higher risk are visits to family and friends or others living on the local economy of developing countries, such as teachers, students, and missionaries. These visitors often travel with children, feel pressure to conform to local customs, do not want to offend local hosts and relatives with their Western differences, are in close contact with indigenous people, and have high exposure to insect-borne disease. Many immigrants return to their native countries having lost their previous partial immunities (e.g., against malaria and diarrhea) and underestimate their risk and that of their children. Travelers at the highest risk are trekkers, campers, bikers, and rafters. Although they are usually better prepared by more pretravel self-education and are more aware of their risks, they are also more adventuresome, more medically compromising, and often financially unwilling to purchase expensive medications and vaccines.
Certain factors in the medical history have special significance to travel medicine. The medical history form in Figure 9.1 highlights these key factors. The existence of any of these conditions or allergies may preclude trips of certain types and may be contraindications to vaccines and medications, such as antimalarial drugs, specifically prescribed for travelers. Implications of a positive reply are covered in the sections Prevention and Preexisting Diseases, below.
The purpose of the patient's pretravel visit is to obtain preventive services. Elements of prevention should include education, immunizations, prophylaxis for malaria and high altitude illness, and medication for traveler's diarrhea.
Education is central to the travel visit. Its role is risk reduction and preparedness for possible problems or aggravation of existing problems. A checklist of those education items (Fig. 9.2) can be used as a prompt for the patient visit.
Water and Food Safety
The maxim is, "Cook it, boil it, peel it, or forget it." Boiling clean water for 3 minutes at any altitude is sufficient. A 1-minute boil will pasteurize water for most situations. Bottled water is generally safe, if the sealed cap is removed only in the tourist's presence. Chlorine and iodine tablets are available in camping stores and sufficiently kill organisms for the immunocompetent; iodine is more efficacious. Water filters are not recommended because of insufficient testing or inadequate filtering of viruses. Avoid all tap water and ice cubes, even if mixed in alcoholic beverages. Milk is often unpasteurized, as are dairy products. All meats and vegetables should be thoroughly cooked and served steaming hot. Avoid all cold buffets, chilled desserts, and salads. Peeling the intact skins of fruits before eating is safe.
Insect Avoidance
The traveler cannot contract certain diseases, fortunately, unless bitten by the vector. Bites of the mosquito, tick, tsetse fly, sandfly, or flea are avoided by applying a repellant containing 20% to 50% diethyltoluamide (DEET) (Sawyer, Repel, Cutter, others) on all exposed skin surfaces. Prolonged or excessive applications of high concentrations can be toxic to young children. Long-sleeve shirts and long pants are essential wear in malarious or dengue areas. Spraying or soaking clothes, mosquito nets, and tents with permethrin (Duranon, Sawyer, others) significantly reduces the number of bites and incidence of malaria.
First-Aid Kit
Inclusion of an antipyretic/analgesic, a topical antibiotic, an insect repellent with 20% to 50% DEET, a sunscreen with an ultraviolet A (UVA) and B (UVB) with sun protection factor (SPF) of 15 or more, an antihistamine, and possibly ipecac and an antifungal gynecologic cream are advisable. It is also the logical place to put any medical records and abnormal electrocardiograms (ECGs).
General Safety Advice
A seatbelt is always used in a taxi, or one should sit in the back seat; it is advisable to be assertive with unsafe drivers. Display of any valuables and money should be avoided. Travelers should never travel with anything they cannot afford to have stolen. In a closed space with a gas heater, a window should be cracked open. The lower stories in hotels are safest, and the nearest operative fire exit should be identified. Antimalarial, chlorine, and iodine tablets in proximity to bored traveling children are a hazardous combination, perhaps warranting ipecac in the cabin bag.
Jet Lag
The best method to entrain circadian rhythms is unknown, although certain measures are helpful. Before travel, adjusting to the new time zone by 1 hour per 24-hour period is helpful. At the destination, taking 5 mg of melatonin at bedtime for the first few days shortens the duration. In the mornings at the destination, bright light is helpful, as is a high-protein breakfast with a caffeinated beverage. Alcohol should be avoided and liberal hydration employed. A prescription hypnotic such as zolpidem (Ambien) also promotes sleep at night.
Motion Sickness
Effective agents for prophylaxis of motion sickness in adults include transdermal scopolamine (Transderm SCOP) applied 8 hours before motion or dimenhydrinate (Dramamine) 50 to 100 mg taken 1 hour before motion and then every 4 to 6 hours. Either may impair performance or produce unacceptable anticholinergic side effects, particularly in the elderly.
Local Practitioners and Pharmacies
Developing-world pharmacies frequently allow the purchase of most medications over the counter. However, wishing to be certain of "curing the problem" and pleasing the patient, local practitioners and pharmacists often overprescribe. For example, traveler's diarrhea might be treated for bacterial causes with chloramphenicol in addition to one or more antiparasitic drugs. The U.S. embassy can provide names of reputable practitioners and hospitals.
Freshwater and Schistosomiasis
All freshwater must be assumed to be fecally contaminated. After any accidental tropical or semitropical freshwater exposure, one should towel off quickly to minimize the risk of schistosomiasis and other waterborne diseases.
Sexually Transmitted Diseases
The anonymity of travel combined with open prostitution places many travelers at risk of sexually transmitted diseases (STDs), including human immunodeficiency virus (HIV) infection. Some individuals travel explicitly for sexual encounters. Openly addressing this possibility with travelers can promote defensive behaviors and encourage safe sex.
Commonsense Advice
(1) Hand-carry all medications in original containers. (2) The first-aid kit should include a copy of any abnormal or unusual ECG, radiologic report, and recent hospital discharge summary. (3) The traveler should verify insurance policy coverage and consider the purchase of medical evacuation insurance. (4) Nasal/sinus congestion should be treated early and aggressively before flying. (5) An injection is never accepted without personally observing the unbroken seals of the sterile needle, syringe, and medication.
Travel vaccines fall into two categories: required and recommended. Unless otherwise stated, most vaccines can be administered simultaneously. A notable exception to coincident administration is immune serum globulin with measles vaccine.
Required Immunizations
The only World Health Organization (WHO) regulated vaccine currently required by countries is yellow fever vaccine. These countries are listed in Health Information for International Travel (HIIT) with updates in Summary of HIIT (Table 9.1). Both cholera and meningococcal vaccines have been required in the past. Until a better cholera vaccine is available, cholera vaccine is unlikely to become officially required even in epidemic conditions. Meningococcal vaccine has been required by Saudi Arabia 10 days before the annual hajji to Mecca.
Only an approved yellow fever vaccination center can administer this vaccine. Some public health departments allow individual practitioners to be a designated center. It is a fastidious live viral vaccine that requires careful handling and use within 1 hour of reconstitution. Serious reactions are uncommon in those less than 65 years old.
Recommended Immunizations
Physicians are familiar with the routine vaccines: tetanus/diphtheria, influenza, and pneumococcal vaccines. The most frequently recommended additional prophylactic agents are immune serum globulin or hepatitis A vaccine, a polio booster, a measles booster, and typhoid vaccines. Special situations might require meningococcal, hepatitis B, Japanese encephalitis, or rabies vaccines. Most authorities are uncertain as to what duration of travel justifies the risk of prophylactic vaccination.
On occasion, elderly patients or persons reared in the developing world and who later immigrated to the United States are found who either never received a primary vaccination series, or their immunization status is unknown. These patients should complete the primary series before traveling. If they are starting their journey before adequate completion of the primary series, they should be informed of the possible inadequacy of their vaccine status. The primary series should be completed on return or continued overseas if safely available.
Recommended vaccines are discussed below in order of approximate frequency of administration to travelers. See Table 9.2 for dosage and frequency.
Hepatitis A or Immune Serum Globulin. Hepatitis A vaccine or the prophylactic agent immune serum globulin (ISG) before each trip is recommended for every traveler to the developing world unless there is evidence of immunity. The vaccine is preferable in most situations. If departure is shorter than the 2 to 4 weeks it takes for adequate efficacy of the vaccine, ISG and the vaccine may be administered together with little effect on subsequent protection by the vaccine. A booster dose of hepatitis A vaccine 6 to 18 months later will probably give lifetime immunity.
Tetanus/Diphtheria. A tetanus/diphtheria booster dose is given every 10 years. Consider a booster after a 5-year interval in high-risk situations. Those situations include trips with likelihood of a cut or puncture wound where sterile needles or properly stored vaccine may be unavailable.
Typhoid. Typhoid vaccination is recommended when the risk of exposure during the protective duration of the vaccine totals more than 5 to 6 weeks. Ty21a, a four-dose oral vaccine, replaces injectable vaccine for routine use in travelers age 6 years and older. The efficacy (>60%) of Ty21a is equal to that of injectable vaccine. Its protection lasts 5 years, and side effects are unusual and mild. Ty21a capsules contain live, attenuated bacteria and should be kept refrigerated and taken on an empty stomach with a cool or tepid beverage. The capsules are taken every other day and separated by several days from antibiotics, mefloquine, and Malarone. Injectable typhoid vaccine, Typhim Vi, is useful for those 2 to 6 years old; it has few side effects and needs only one dose as a primary series, but lasts only 2 years.
Poliomyelitis. Injectable enhanced polio vaccine (eIPV) is a safe, effective booster. It is given as a one-time adult booster if traveling to an endemic area. If the patient's primary series is incomplete or unknown and there is not enough time to complete the primary series before travel, a single booster dose of either injectable or oral (OPV) vaccine is recommended. It is not needed for the polio-free Western Hemisphere and some countries of the Western Pacific.
Measles/Rubella. For patients born after 1956, a second booster of measles vaccine is suggested. It is given at least 2 weeks before ISG or its efficacy cannot be ensured. In female travelers, combine it with rubella unless immunity to rubella is known. Pregnancy is contraindicated during the next 3 months. Frequently, the traveler is departing before the 2-week interval needed between ISG and measles vaccine. Use of ISG takes priority, with or without hepatitis A vaccine.
Meningococcus. Meningococcal meningitis is periodically epidemic in parts of Nepal and in a band across sub-Saharan Africa stretching from Mali to Ethiopia and Uganda. It will probably continue to be required by Saudi Arabia for pilgrims on hajji to Mecca. The quadrivalent A,C,Y,W-135 vaccine should be administered at least 10 days before arrival; it has few side effects.
Hepatitis B. Seroconversion is common for those residing in the developing world.1 Therefore, hepatitis B is recommended for (1) travelers staying 6 months or longer, (2) pleasure seekers who might be sexually exposed, and (3) medical personnel. The primary series takes 6 months to complete, but a schedule with Engerix-B given at 0, 1, and 2 months produces excellent seroprotection,2 with an additional booster suggested at 12 months if exposure continues. A more accelerated schedule of the same vaccine given on days 0, 7, and 21 or 28 has also resulted in good immunogenicity at 12 months3 (see Chapter 90).
Influenza. Influenza may spread throughout an airliner.4 Therefore, influenza vaccine use is encouraged during the usual influenza season in the Northern Hemisphere and during the spring and early summer for travelers to the Southern Hemisphere (see Chapter 39).
Rabies. Many countries are highly endemic for rabies. Travelers are not at high risk, but the expensive vaccine and rabies immune globulin are not available in most countries. Long-term travelers, children, cyclists, and pet adopters should consider preexposure vaccination.
Cholera. The injectable cholera vaccine is no longer produced. The rare risk of this disease to travelers makes this vaccine rarely indicated, even during epidemics. Oral vaccines are more promising and available in other countries.
Japanese Encephalitis. A mosquito-borne arboviral infection, Japanese encephalitis is the leading cause of viral encephalitis in Asia. The Japanese encephalitis vaccine is indicated for travelers spending more than 30 days in the rural areas of countries on the Pacific Rim from India to China and east to the Philippines and Japan. The greatest risk is during the rainy season, April to October, and is minimal in urban areas. The three-dose primary series is administered over 14 or, preferably, 30 days and must be finished 10 days before travel begins. HIIT has a table of risk by country.
The need for an antimalarial prescription is a common reason for travel consultation. The most important advice is the mosquito avoidance measures described earlier. The second important component is prescribing the best antimalarial prophylaxis. Areas of the world with chloroquine-sensitive malaria, though shrinking, are still found in Mexico, Central America, and the Middle East. For simplicity, one could assume that all malarious areas are chloroquine-resistant. None of the prophylactic and mosquito avoidance measures are 100% effective.
Mefloquine (Lariam)
Probably the most prescribed antimalarial, mefloquine, is effective in both chloroquine-resistant and chloroquine-sensitive areas. It is taken once weekly starting 1 to 2 weeks before arrival in the malarious area, taken once weekly during possible exposure, and continued for 4 weeks after the last possible exposure. Most side effects, which are usually transient and occur during the first two doses, consist of dizziness, strange dreams, and insomnia. It has been reported to cause serious neuropsychiatric adverse effects in 1/10,600 users.5 These effects are seizures, anxiety, depression, or psychotic episodes. Therefore, it should not be used in travelers with epilepsy or serious psychiatric illness. It is relatively contraindicated in those with cardiac conduction abnormalities and the first trimester of pregnancy. Resistance is rare.
Atovaquone/Proguanil (Malarone)
Atovaquone/proguanil (Malarone) is the newest antimalarial and available in adult and pediatric doses. It is very effective prophylaxis for chloroquine-resistant malaria and can be use in children weighing more than 11 kg. Ingested with food or a milky drink, one starts 2 days before exposure, continues daily during exposure and daily for only 7 days after last possible exposure. Its cost is prohibitive for exposures longer than about 7 days. However, side effects are infrequent and the same as a placebo.
Doxycycline
Effective against chloroquine-resistant malaria in lieu of mefloquine, possible phototoxic side effects limit the general use of doxycycline in tropical areas. Start 1 day before possible malaria exposure, continuing daily during exposure and for 4 weeks after the last possible exposure. Its use requires meticulous application of a sunscreen (SPF >15) with UVA-blocking properties; women should carry an antimonilial vaginal cream. Doxycycline is contraindicated in children under 8 years old.
Chloroquine Phosphate (Aralen)
Chloroquine phosphate is useful in chloroquine-sensitive malarious areas. The dosage is one 500 mg tablet (Aralen) in adults and 5.0 mg/kg of the base weekly in children, starting 1 week before possible exposure, weekly during exposure, and for 4 weeks after the last possible exposure. Side effects of chloroquine, which are infrequent, consist of dizziness or gastrointestinal upset, and the drug can precipitate a flare of psoriasis. For children, mixing it in jam lessens its bitter taste. It is toxic in overdose and should be stored in a childproof container.
Primaquine Phosphate
Useful for postexposure elimination of the hepatic forms of Plasmodium vivax and Plasmodium ovale, there is little indication for primaquine in the returning short-term traveler. However, even without symptoms, it should be considered if the exposure period is longer than 6 months. Before administration, a normal glucose-6-phosphate dehydrogenase (G6PD) level should be confirmed.
The incidence of traveler's diarrhea (TD) ranges from 4% to more than 50%; it is the most preventable and easily treatable disease of travelers. For perspective, 4% of European travelers to the United States acquire TD,6 and the attack rate for the developing world ranges from 20% to 56%.7 A National Institute of Health (NIH) consensus conference defined TD as a syndrome characterized by a twofold or greater increase in the frequency of unformed bowel movements. Commonly associated symptoms include abdominal cramps, nausea, bloating, urgency, fever, and malaise. Episodes of TD usually begin abruptly, occur during travel or soon after returning home, and are generally self-limited. TD typically results in four or five loose or watery stools per day. The median duration of diarrhea is 3 to 4 days. Ten percent of the cases persist longer than 1 week, approximately 2% longer than 1 month, and less than 1% longer than 3 months.8 Rapid treatment can shorten the duration to a matter of hours, an important factor for expensive tourist and short business trips. Bacterial etiologies account for 37% to 72+% of cases. The most common bacteria, in approximate order of frequency, are enterotoxigenic Escherichia coli, Shigella, Campylobacter jejuni, Salmonella, and Vibrio spp. The most common viral etiologies (responsible for up to 36% of cases of TD) are rotavirus and Norwalk viruses.7 Parasites, primarily Giardia lamblia and Entamoeba histolytica, cause up to 9% of cases. Frequently more than one pathogen is found during a diarrheal illness, and 20% to 50% of cases of TD remain unexplained.8
Prophylaxis
Generally, antibiotic prophylaxis is avoided. The first line of prevention is food and water safety and vaccination; these points were covered earlier in the chapter (see Prevention). Prophylaxis is justified in special circumstances where the risk of TD must be minimized and requires a short duration of antibiotic exposure. These situations might include an international sporting event, a honeymoon, or an intense, high-level business meeting. Agents with prophylactic efficacy include bismuth subsalicylate (Pepto-Bismol) 2 tablets qid; norfloxacin (Noroxin) 400 mg qd; ciprofloxacin (Cipro) 500 mg qd; ofloxacin (Floxin) 300 mg qd; and perhaps, doxycycline (Vibramycin) 100 mg qd.
Treatment
Rapid treatment of adults can reduce the duration of TD to 1 day or less. The fluoroquinolones provide the broadest coverage against the bacterial etiologies of TD. Their cost limits widespread use in developing countries, resulting in infrequent resistance to this class of antibiotics. If there is no fever or bloody diarrhea, start with two loperamide (Imodium) capsules after the first loose stool and continue at the usual doses of loperamide. If the diarrhea continues after the third loose stool, give two tablets of either ciprofloxacin 500 mg or norfloxacin 400 mg. Most TD stops at this point, but if it still continues give one tablet of the fluoroquinolone bid for 3 days. Rifaximin, a luminal antibiotic dosed at 400 mg tid for three doses appears promising and available in Europe. Distant second-line alternatives are bismuth subsalicylate 30 mL every half-hour for eight doses or doxycycline 100 mg two bid for 3 days. Antidiarrheal agents are not recommended for children. Azithromycin (Zithromax) at usual doses has some efficacy. Oral rehydration solution (ORS) is the best treatment for young children. ORS packets promoted by WHO are available in most developing-world pharmacies or clinics. Mixed in 1 L of safe water, they are safe and effective. Introduce safe foods of the same consistency as the diarrheal stools.
The axiom is "climb high, but sleep low." The incidence of high-altitude illness increases with ascent above 2500 m (8200 feet). The prevalence is 9% at 2850 meters (9350 feet) and 34% at 3650 meters (12,000 feet).9 Common to the syndromes of acute mountain sickness (AMS), high-altitude pulmonary edema (HAPE), and high-altitude cerebral edema (HACE) are rapid ascent and tissue hypoxia. The latter results from the lower partial pressure of oxygen at high altitudes. AMS ranges from a mild illness (headache being the most common symptom, followed by nausea or lassitude) to a severe illness (vomiting, dyspnea at rest, ataxia, mental impairment, or cyanosis). HAPE can develop after several days, usually during sleep, with symptoms of extreme dyspnea, cough, rales, mild fever, and cyanosis. HACE can develop after several days of mild AMS, presenting with progressively severe lassitude, decreasing alertness, psychosis, focal neurologic signs, and eventual coma. Predisposing factors to these syndromes are poorly understood but include more exertion and prior residence at less than 3000 feet.
The best prophylaxis is slow ascent, less than about 300 m (1000 feet) per day. For rapid ascents above 3000 m (9800 feet) lasting more than 12 hours, consider prophylaxis with 125 to 250 mg acetazolamide (Diamox) bid, starting 24 hours before ascent and continuing during the first 2 to 4 days at high altitude. Over-the-counter analgesics are adequate for the headache. Acetazolamide can be reserved to treat mild cases of AMS. Although dexamethasone (Decadron) 4 mg q6h can be used for prophylaxis, it is usually reserved for treatment of severe AMS, HAPE, or HACE. Once dexamethasone is started, high-flow oxygen and descent should begin emergently.
Several diseases noted by the history form require elucidation. Generally, travelers should treat aggravation of a preexisting disease early and aggressively. Travelers must be prepared for the disease exacerbations they can manage.
Patients with chronic obstructive pulmonary disease (COPD) may require arterial blood gas determinations before travel (see Chapter 83). Aircraft maintain cabin pressure equivalent to 2438 m (8000 feet) or less. This altitude results in a fall of partial pressure of arterial oxygen (PaO2) to approximately 60 mm Hg in healthy individuals. Though prediction of hypoxemia in the COPD patient is difficult, patients with a preflight PaO2 of less than 70 mm Hg or oxygen saturation of less than 93% should receive supplemental oxygen from the airline during the flight.10 Individuals with preflight hypercapnia or vital capacity of less than 50% should travel by land or obtain specialty consultation.
Because of the frequency of upper respiratory infections and pollution in the developing world, the traveler should expect to experience an exacerbation of asthma (see Chapter 83). Travelers should follow their peak flow readings and must know how to self-medicate with antibiotics and corticosteroids to the limit of their ability.
Airline travel should be restricted for 4 to 8 weeks after myocardial infarction and supplemental oxygen considered for the following 4 months (see Chapter 76). A general rule is that the cardiac patient should be able to walk 100 yards and climb 12 steps,11 although an exercise treadmill test will give a more precise functional capacity.
Prohibit airline travel for 10 to 14 days after abdominal surgery12 (see Chapter 87). The minimum time after laparoscopy using CO2 inflation is unknown, but airline travel should be safe after 48 hours. As hypochlorhydria and H2-blockers diminish the stomach's natural barrier to traveler's diarrhea and cholera, consider prophylaxis or aggressive treatment and liberalize indications for vaccination.
Special provisions for handicap needs should be made in advance with the airline. Information on travel for the handicapped can be obtained from most organizations for seniors or for the specific handicap. Arthritides should be well controlled with the expectation of some aggravation (see Chapters 112,113).
Most returning short-term travelers do not need evaluation. Arbitrarily, those who have had an exposure of 6 months in the developing world should have a complete blood count to check for anemia and eosinophils and one to three fecal examinations for ova and parasites. A history of other possible exposures guides additional testing.
For the symptomatic traveler the history should focus on symptoms or illnesses during the travel. It should consider sexual and freshwater exposures, prophylactic compliance, and the exact travel itinerary to determine possible exposures. This risk assessment guides the evaluation. Whatever the symptoms, if malaria exposure was possible, start with examination of thick and thin blood smears. If the illness continues or the index of suspicion is high, the malaria smears should be repeated as frequently as every 6 hours. A technologist experienced in reading malaria smears is preferable, as the parasitic load may be light in nonimmune travelers but the patient very ill. Urinalysis, a fresh fecal specimen for culture, and three specimens for ova and parasites often reveal most of the common problems. Otherwise, evaluation of a febrile illness can proceed in an orderly, routine fashion. Tests to consider early in the evaluation would be those for liver function, malaria antibodies, hepatitis serologies, schistosomiasis serology, HIV screen, and rickettsial serologies. A rapid plasma reagin test for syphilis and an intermediate-strength purified protein derivative skin test screen for the great imitators.
Staying healthy abroad is not always easy, but pretravel education with proper prophylaxis and vaccination can prevent the most common maladies. The world is shrinking, and it has never been easier for patients to savor its differences, its mystery, and its excitement. The family physician can take the lead in preventing the resurgence of the old scourges such as malaria and diphtheria and in limiting the spread of emerging diseases.
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