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Journal of Occupational & Environmental Medicine:
doi: 10.1097/JOM.0b013e318180804f
Special Section on Health and the Corporate Traveler

Overview of Selected Infectious Disease Risks for the Corporate Traveler

Hudson, T Warner MD, FACOEM, FAAFP; Fortuna, Joseph MD

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Author Information

From DST Output (Dr Hudson), El Dorado Hills, CA; Department of Family and Community Medicine (Dr Hudson), University of California Davis Medical Center, Sacramento, CA; and Delphi E&C Division (Dr Fortuna)

The content of this supplement was discussed and guided during a roundtable meeting attended by Dr. Bradley A. Connor, William B. Bunn, Douglas Patron, T. Warner Hudson, Joseph A. Fortuna and Pamela Hymel. The authors did not receive financial compensation for writing these manuscripts.

Address correspondence to: T. Warner Hudson, MD, FACOEM, FAAFP, DST Output, 5220 Robert J Mathews Pkwy, El Dorado Hills, CA 95762; E-mail:

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International business travel to under-developed and developing countries has increased considerably over the past two decades. Most of these destinations are endemic to a variety of infectious diseases, many of which are associated with considerable morbidity, mortality, or both and the nonimmune, unprepared corporate traveler is at risk. Comprehensive pretravel consultation is essential to prevent travel-related illness. This review addresses some of the infectious diseases that can be acquired during international travel, including regions of endemicity, assessment of risk, and available means of prevention. In addition, we discuss data concerning current practices and attitudes of travelers, along with some of the issues surrounding the counseling of corporate travelers.

One of the most common unwelcome events associated with travel to under-developed and developing countries is illness. Over the past two decades, significant increases in international travel have been observed, including travel to developing countries where a variety of infectious diseases are endemic. Between 1990 and 2000, overseas international travel increased 70%, including marked rises in travel between the United States and South America, Africa, and Asia.1 Although noticeable declines in international travel occurred after September 11, 2001, travel numbers have rebounded, but have not yet reached 2000 travel levels. In 2005, there were almost 29 million overseas departures from the United States, a 23% increase from 2002.2 An increase in air travel from the United States to Asia, the Caribbean, and South and Central America was observed between 2005 and 2006, whereas there was a decrease in travel to Africa and the Middle East.3

Increased international business travel has also been reported. In 1990, there were 60.4 million international business travelers worldwide, which made up 13.8% of all international travelers; this rose to 119.3 million (15.6% of travelers) in 2004, nearly doubling the number of business travelers compared to 19904 (Fig. 1). During 2005, there were almost eight million overseas US business travelers—the major destinations being Western Europe (43%) and Asia (32%).5

Fig. 1
Fig. 1
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Travel may pose health risks that can result in illnesses ranging from jet lag to thrombophlebitis to life-threatening infectious diseases. Approximately 42% to 75% of people traveling to developing countries have some travel-related health impairment, which is defined by the use of any therapeutic medication or subjective illness.6–8 In addition, a total of 10% to 20% of people traveling to developing countries have consulted a physician due to travel-related illness, either abroad or after returning home.7,8

Infectious diseases contracted abroad during business travel have both a medical and financial impact on society. The financial impact has many levels, including corporate (eg, lost productivity and workers' compensation) and personal (eg, medical expenses and lost wages). In addition, international business travelers file a greater number of health insurance claims compared to their nontraveling coworkers; 80% higher for men and 18% higher for women. It is noteworthy that a significant proportion of these claims were related to infectious diseases.9 Therefore, it is important to understand the knowledge and behaviors of international business travelers, along with their actual travel health risks, to properly advise and prevent the acquisition of potentially debilitating illnesses.

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Knowledge, Attitudes, and Practices of International Travelers

International travelers can significantly reduce their risk of acquiring an illness by seeking and following accurate, up-to-date travel health advice, such as appropriate vaccinations, chemoprophylaxis, and/or dietary restrictions. Nevertheless, studies of the knowledge, attitudes, and practices of international travelers are limited. Assessments of international travelers' knowledge, attitudes, and practices were conducted in North American, Australian, and European airport surveys10–14 among those seeking pretravel health consultations,6 and through other venues.15

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In general, international travelers' knowledge of actual disease risks while traveling abroad is low, whereas awareness of recommended prevention measures is higher. In US airport survey, with the majority of individuals traveling to Latin America and Asia, less than 20% correctly consider hepatitis A, hepatitis B, or typhoid fever to be high risk.10 Meanwhile, 73% of travelers to high-risk malaria-endemic regions can accurately assess their risk of disease, whereas 12% are not aware of the risk of contracting malaria.10 Of those traveling to high-risk malaria-endemic regions, many believe that antimalaria medication will be available at their destination.10 A similar level of malaria risk awareness was observed in a European airport survey.11,12

A general lack of traveler's knowledge is also reported for hepatitis. Only 17% to 28% of travelers correctly recognize hepatitis A as one of the highest risks among travel-related vaccine-preventable diseases.10,11 Also, many travelers do not realize the modes of transmission for both hepatitis A and B. For example, more than 60% of Canadian travelers do not know hepatitis A can be contracted by eating contaminated food or through sexual contact, and only 42% identify sexual activity as a mode of transmission for hepatitis B.14

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Among surveyed travelers in Europe and the United States, only 15% to 26% intend to completely restrict their consumption of potentially dangerous foods (tap water, ice cubes, ice cream, unpeeled or uncooked fruit, salads, and shellfish), whereas a greater proportion (60% to 90%) plan to partially restrict consumption and the majority (59% to 70%) do not plan to drink local tap water.10–12 Interestingly, most (74% to 83%) international travelers consider vaccines to be protective.10,11

Regarding malaria attitudes, up to 90% of travelers to malaria-endemic areas have intentions to utilize at least one physical or chemical protective measure to prevent infection with malaria.10,11 These measures include using mosquito repellent, wearing long pants and long sleeves, sleeping in an air-conditioned room with all windows and doors tightly shut or sleeping under a mosquito bed net, and using insecticides indoors. Moreover, among those traveling to high-risk malaria regions, 46% to 84% plan to use chemoprophylaxis.6,10,11 In contrast, close to half of the surveyed US travelers to malaria-endemic regions not carrying chemoprophylaxis say they do not like taking medication when they are healthy.10 Similarly, some travelers fear the side effects associated with various antimalaria drugs.6,10

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In 2005, according to the US Department of Commerce, Office of Travel and Tourism Industries, the average time between the decision to travel and the departure date for US international business travelers is 51.7 days. Only 69% of international business travelers book lodging in advance, and 79% stay in a hotel for an average of 8.4 nights. The average number of nights spent outside of the United States is 14.0.5 Other sources, particularly survey results, indicate shorter preparation time; approximately one fourth of international travelers make travel plans within 2 weeks of departure, and 19% to 70% do not seek travel health advice.10–14 Travel medicine and corporate clinicians may have to advise travelers who have only a couple of days to prepare for their trip.

Among travelers who do not seek medical advice, approximately 20% do not know that pretravel consultation is recommended.10,11 Travel health advice is obtained from a variety of sources, including family physicians, travel health clinics, company doctors (business travelers), travel agents, the Internet, books and pamphlets, and family and friends. Unfortunately, not all of these sources, particularly those coming from nonmedical sources, provide accurate, up-to-date travel health advice.16 For 60% to 72% of travelers, family physicians are the most common source of information.10–12

Only 16% of business travelers report fully comply with antimalaria regimens, which include chemoprophylaxis and mosquito bite protection.15 In addition, business travelers are less likely than tourists to carry antimalaria medication.11 Furthermore, whereas hepatitis A is correctly recognized as one of the greatest risks among the vaccine-preventable diseases and most travelers recognize the protective effect of vaccines, less than 24% are vaccinated against hepatitis A. Similarly, less than 29% are immunized for hepatitis B.10,11,13

In addition to lacking proper immunization, further risk is incurred when international travelers have unexpected exposure to the blood and body fluids of those residing in high-risk areas through unanticipated medical treatment or casual sexual activity.17 Up to 55% of international travelers have unanticipated casual sex, particularly with local residents, and a significant percentage (30% to 65%) do not use condoms.18–22 Other high-risk activities include tattooing, body piercing, and sharing razor blades or toothbrushes.17,23

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Nonvaccine-Preventable Diseases

Travelers' Diarrhea

Travelers' diarrhea (TD) is the most common adverse health issue that affects international travelers.8,14,24 On an average, 20% to 70% of travelers to high-risk areas will develop TD during a 1- or 2-week stay. Worldwide, approximately 50,000 cases of TD occur each day.25,26 Countries with the highest risk for TD are in Central America, tropical South America, the Caribbean, most of Africa (with the exception of South Africa), the Middle East, and South and Southeast Asia25 (Table 1).

Table 1
Table 1
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Classic TD is characterized by three or more unformed stools per 24 hours, with at least one accompanying symptom, such as urgency, abdominal cramps, nausea, vomiting, or fever.8 A total of 85% of TD cases are due to bacterial infections, 10% are due to parasites, and 5% are due to viral infections.25 Among the bacterial causes, enterotoxigenic Escherichia coli (E. coli) is the most common cause of TD.8,25 Other bacteria responsible for TD are enteropathogenic, enteroaggregative, enteroadhesive, and enteroinvasive E. coli, Campylobacter jejuni, Aeromonas hydrophila, Plesiomonas shigelloides, Salmonella spp., Shigella spp., and Vibrio spp.8,25,26 Approximately 30% to 40% of TD cases remain unexplained, but presumed to be bacterial in origin because patients respond to antibiotics.8,26

The famous pretravel advice of “boil it, cook it, peel it, or forget it” clearly describes dietary restrictions that need to be used to lessen the risk of TD. Dietary restrictions include: 1) Drink only tap water that has been boiled for at least 3 to 5 minutes. Avoid ice cubes made from tap water that has not been boiled. Coffee or tea made from boiled tap water should be consumed while still very hot. Bottled beverages are generally safe. 2) Avoid raw or rare-cooked meat and fish, as well as dairy products. Well-cooked foods and baked goods are usually safe. 3) Fresh fruits and vegetables should be avoided unless carefully washed and peeled by the traveler.26

A number of antibiotics can be used as chemoprophylaxis for bacterial TD. Effectiveness varies depending upon the traveler's destination and which antibiotic is prescribed (predominant causative strains and the degree of antibiotic-resistance)26; however, the use of antibiotics for chemoprophylaxis is not generally preferred because of the risk of adverse effects, the development of drug resistance, cost, and the promotion of a false sense of safety for the traveler, which could lead to risky behavior. Preventive antibiotic use is usually recommended for high-risk travelers, such as those with autoimmune disorders or human immunodeficiency virus (HIV).26,27 Bismuth subsalicylate is an effective, albeit cumbersome, preventive measure, whereas the use of probiotics prophylactically has not been proven effective and is not recommended27 (Table 1).

Early treatment of TD is essential to shorten duration, reduce discomfort and incapacitation, and prevent the development of severe complications, particularly dehydration and electrolyte imbalance. Treatment measures include oral rehydration, symptomatic, and antimicrobial therapies. Oral rehydration ideally involves the use of adequate amounts of commercially available rehydration solutions that contain optimal concentrations of glucose, sodium, and potassium to facilitate the absorption of water and sodium.26,27 Symptomatic therapy includes the use of bismuth subsalicylate and loperamide, which decrease the number of unformed stools. Loperamide acts rapidly by inhibiting intestinal motility.

Antimicrobial treatments such as fluoroquinolones, azithromycin, and rifamixin are sometimes prescribed to facilitate recovery.26,27 Increasing resistance to fluoroquinolones is a concern and fluoroquinolone use has resulted in antibiotic-induced diarrhea caused by Clostidium difficile, which can be considerably more severe than untreated TD, with a longer duration of symptoms and greater toxicity.

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Malaria is one of the leading causes of death due to illnesses contracted while traveling, and is the most common cause of febrile illness among international travelers, particularly those who have been to Africa8,24,28 (Table 1). In 2005, there were 1528 cases of malaria reported to the Centers for Disease Control and Prevention (CDC), a 15.4% increase from 2004.29 The majority, 70.2%, of imported cases among US civilians were acquired in Africa. In total, 11.5% of civilians contracted the disease in Asia and the Middle East, and 9.4% contracted it in Central America and the Caribbean.29

Malaria infection occurs when a mosquito carrying the Plasmodium parasite feeds on a human, transferring the infection via its saliva. This ultimately leads to infection of red blood cells and hemolysis.30 Symptoms range from fever, chills, nausea, and vomiting, to anemia, kidney failure, and seizures. Complications of malaria can be fatal.30,31 International travelers to malaria-endemic areas are advised to take chemoprophylaxis and protect themselves from mosquito bites (Table 1). For more on malaria and its prevention, please see the accompanying article on malaria in this supplement.

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Dengue Fever and Dengue Hemorrhagic Fever

Dengue fever and dengue hemorrhagic fever are among the most rapidly expanding diseases in most tropical and subtropical regions of the world, and the most common mosquito-borne viral disease.25 More than 2.5 billion people live in high-risk areas. Attack rates during epidemics are 1/100 to 1/1000 people. Infection rates, which encompass the infected population, including those with less severe or unreported symptoms, are estimated to be 5- to 10-fold higher than the attack rates (25, 2007 #35). Epidemics have been progressively more frequent and larger over the past 25 years,25 coinciding with the geographic spread of mosquitoes (Aedes spp.) and the causal viruses.32 As of 2005, dengue fever was endemic in most tropical countries of the South Pacific, Asia, the Caribbean, the Americas, and Africa, and the estimated risk to travelers to these regions is 1/1000 travelers25 (Table 1).

Analysis of data collected from approximately 7000 travelers with febrile illness reported to GeoSentinel sites across the globe from March 1997 through March 2006 revealed that dengue was the most frequent cause of fever in travelers returning from Southeast Asia, South-Central Asia, the Caribbean, Central America, and South America.33 (For more information on GeoSentinel sites visit In 2005, 96 cases of dengue were confirmed by the CDC.34 Nearly as many cases of travel-associated dengue were identified in 2005 as were identified during the previous 5 years combined.34–36

Four immunologically related viruses, DEN-1, -2, -3, and -4 can cause illness. Nevertheless, an immune response to one virus does not provide cross-protection to another.25,32 Multiple serotypes can be circulating in the same geographic region.37

The case-fatality ratio for dengue hemorrhagic fever averages approximately 5% worldwide.25 Consequences of reinfection from any serotype can be very severe and increase one's risk for developing hemorrhagic fever and, therefore, death.36 The best way to avoid contracting dengue is to avoid mosquito bites, as no vaccine is currently available (Table 1).

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Human Immunodeficiency Virus

HIV is globally prevalent (Table 1), with an estimated 40 million persons living with HIV or acquired immune deficiency syndrome worldwide, and approximately 14,000 new infections on a daily basis.25,38 There were 4.3 million new infections in 2006, with 2.8 million (65%) occurring in sub-Saharan Africa.38 Prevalence rates are particularly high in Africa, ranging from 17% to 32%.39 Significant increases in new infections were observed in Eastern Europe and Central Asia.38 As such, risk to the international corporate traveler is determined more by behavioral risk factors than by destination. HIV infections acquired during travel have been reported in more than 160 countries, with sexual transmission as the primary mode of transmission.39

Because HIV is transmitted through blood and semen and vaginal secretions, unprotected sex with an infected individual or the use of contaminated needles are the major sources of infection for travelers, similar to the risk factors associated with hepatitis B. Business travelers, both short- and long-term, are known to have casual sex with local residents, including prostitutes, and condom use is inconsistent.39,40 Exposure through contaminated needles can occur with intravenous drug use, tattooing, body piercing, or acupuncture.25

Further risk is incurred when international travelers have unanticipated medical treatment.17 Injections in health care settings in developing countries that use improper infection-control procedures and unsanitary injection equipment have been identified as major sources of HIV transmission.41 In 2000, in regions of the world with high disease burdens, 39.3% of administered injections involved reused equipment. Overuse of injections is common, and reuse of injection equipment occurs in almost one in three injections in developing and transitional countries.41 This resulted in an estimated 260,000 new HIV infections in 2000.42 Furthermore, HIV infection can be acquired through the receipt of contaminated blood, blood products, or clotting factor concentrates administered in countries where donated blood and plasma are not screened for HIV.25

There is no vaccine available to prevent the acquisition of HIV (Table 1). Consistent condom use and the avoidance of contaminated needles can reduce the risk of infection. The CDC recommends that travelers, men and women, bring their own condoms, because some areas may have limited supply, or available condoms may be of lower quality.25

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Vaccine-Preventable Diseases

Seasonal Influenza

Travelers' risk for influenza depends upon season and destination. A survey of European travelers found influenza to be the most frequent vaccine-preventable infection among travelers to subtropical and tropical countries.43 In tropical regions, influenza can be endemic all year, whereas in temperate regions of the Southern Hemisphere, most cases are contracted between April and September (Table 1). Thus, US travelers can be exposed to influenza in the summer when traveling abroad.25

The Advisory Committee on Immunization Practices and the Infectious Disease Society of America strongly recommend influenza vaccination for individuals traveling to the tropics, those traveling with organized tourist groups any time of year (such as a cruise), or those traveling to the Southern Hemisphere from April through September who were not vaccinated during the previous fall or winter and are at high risk for complications from influenza.44,45 It should be noted that vaccine composition for the Northern and Southern Hemispheres can be different and are available at different times of the year. Just recently, the Advisory Committee on Immunization Practices has further expanded its recommendation to include any traveler who wishes to reduce the risk of influenza infection45 (Table 1).

There are two types of influenza vaccines currently available: live, attenuated influenza vaccines (LAIV), and inactivated influenza vaccines. Both vaccines are effective and designed to be antigenically equivalent to the annually recommended strains.44 They are administered annually to provide optimal protection. LAIV can produce mild symptoms and is recommended only for healthy individuals, aged 5 to 49. Currently, Flumist (MedImmune Vaccines, Inc.; Gaithersburg, MD) is the only LAIV licensed in the US.46 It is administered via a single dose intranasal spray.44,46 Side effects associated with LAIV include nasal congestion, headache, sore throat, tiredness, muscle aches, wheezing, and cough.46 The inactivated vaccines, usually administered as a trivalent vaccine, are recommended for most individuals, including those who cannot receive LAIV, such as persons with chronic disorders, compromised respiratory function, recent hospitalization, pregnant women, and breast-feeding mothers. Three inactivated vaccines are approved for use in the US—Fluarix (GlaxoSmithKline; Rixensart, Belgium), Fluvirin (Novartis Vaccines; Cambridge, MA), Flulaval (ID Biomedical Corporation; Quebec City, QC), Afluria (CSL Limited; Parkville, Victoria), and Fluzone (Sanofi Pasteur; Swiftwater, PA).47–51 They are administered to adults via a single intramuscular injection.44 In addition to pain, redness, and swelling at the injection site, adverse events associated with these vaccines include those reported for LAIV.47–51 In addition, Guillain-Barré syndrome and other acute neurological disorders have been associated with both types of influenza vaccines.46–51

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Yellow Fever

Yellow fever (YF) is a viral infection transmitted through mosquitoes.25,32 Symptoms vary from flu-like illness to severe hepatitis and hemorrhagic fever.25 The case-fatality rate is greater than 20%, and infants and children are at the greatest risk of death.25 YF is only seen in sub-Saharan Africa and tropical South America, where it is endemic and intermittently epidemic25 (Table 1). There are three transmission cycles: sylvatic, intermediate, and urban epidemic. The sylvatic cycle occurs when mosquitoes bite infected monkeys, and then bite a human in the forest, which results in sporadic cases among people who work in the jungle.32 Intermediate cycles cause small-scale epidemics in rural villages when semi-domestic mosquitoes bite monkeys in the humid or subhumid savannahs of Africa and then infect humans in nearby villages.32 Urban epidemics are of the most concern, and occur when domestic mosquitoes transmit the virus from person to person. An infected individual from a rural area introduces the virus into an area with a high human population density and the epidemic spreads rapidly outward from a central starting point.32

Travelers' risk for contracting YF is determined by their immune status, location of travel, season, duration of exposure, occupational and recreational activities while traveling, and local rates of transmission.25 For the US traveler, overall risk of YF is 0.4 to 4.3 per million travelers.25 The risk to travelers is 10 times higher in West Africa than in South America.25 Approximately 2.5 million US travelers visit YF-endemic areas annually, and the number continues to rise.52 In the United States, from 1996 to 2000, only five cases of YF were reported. Four of those five cases were contracted in South America, and all five were fatal. It is important to note that the five individuals were not immunized.25 It is possible that physicians are not recommending vaccination for those traveling to South America, and as a result, acquisition of infection is occurring there.

Table 2 provides a complete list of countries which are endemic for YF, along with a list of countries which require proof of vaccination for entry. More detailed, up-to-date information can be obtained from either the CDC ( or the World Health Organization.53

Table 2
Table 2
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YF-VAX (Aventis Pasteur, Inc.; Swiftwater, Pennsylvania), a live virus vaccine, is the only YF vaccine licensed for use in the United States, and it is the only required vaccination for certain tropical destinations25 (Table 1). The vaccine is supplied to authorized YF vaccination centers, where valid certificates of vaccination can be issued.54 Historically, YF vaccination is very safe, but reports of rare serious adverse effects, including death due to multiple organ system failure, have been reported, and there is an increased risk for side effects among individuals over the age of 60.52,54–56

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Typhoid Fever

Typhoid fever (typhoid) is caused by Salmonellaentericatyphi, and is an acute, febrile, life-threatening illness. The most common cause of transmission is consumption of fecal-contaminated food or drink, and it can be contracted during an international trip lasting less than 1 week.25 The disease typically presents as a persistent, high fever. Other common signs and symptoms include headache, malaise, anorexia, splenomegaly, and relative bradycardia.25,57

Each year, worldwide, there are approximately 22 million typhoid cases and 200,000 deaths due to typhoid.25,58 In the United States, approximately 400 cases of typhoid are reported to the CDC each year.25 Although the number of reported cases of typhoid in the United States in 2004 was the second lowest total since 1972, approximately 75% of all cases occurred in individuals who reported international travel the month prior—this is despite the availability of two effective vaccines and their recommended use for international travelers.59

The risk of acquiring typhoid fever for the traveler is 1 to 10/100,000 travelers, depending upon destination60 (Table 1). Risk is particularly high in the Indian subcontinent; the majority of cases (approximately 75%) reported in Great Britain and the United States were acquired in this region.57,61,62

Clinical diagnosis can be difficult because of nonspecific symptoms, so travel history to areas of endemicity should alert the physician to possible typhoid fever.57 Definitive diagnosis requires isolation of Salmonellatyphi from blood, bone marrow, or another extraintestinal site.57 Effective treatment includes administrating effective antibiotics and carefully monitoring electrolyte and fluid levels.57 It has been reported that increasing numbers of Salmonellatyphi isolates are resistant to multiple drugs commonly used to fight infection, such as ampicillin, chloramphenicol, ciprofloxacin, and trimethoprim-sulfamethoxazole.57,63

Vaccination plus dietary restrictions are the most effective way to avoid typhoid infection (Table 1). Although vaccination is not required for travel, it is recommended for travelers to high-risk regions. These regions include developing countries in Asia, Africa, South America, Central America, the Caribbean, and the Indian subcontinent.25 Two vaccines are currently available. There is an oral, live, attenuated vaccine (Vivotif Berna; Swiss Serum and Vaccine Institute; Berne, Switzerland), which is dosed in four capsules, taken every other day. The regimen should be completed at least 1 week prior to travel. The second vaccine is a Vi capsular polysaccharide vaccine (ViCPS) (Typhim Vi; Aventis Pasteur; Swiftwater, PA). It is administered via a single intramuscular injection, at least 2 weeks before travel. Both types of vaccine provide varying levels of protection, 50% to 80% efficacy, therefore, travelers should still follow dietary restrictions.25,27,57 There are very few reports of serious side effects from typhoid vaccination, and all persons traveling to high-risk destinations, regardless of duration of stay, should be vaccinated.62

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Viral Hepatitis
Hepatitis A.

Hepatitis A is one of the most common vaccine-preventable diseases acquired abroad.25 Travelers' risk is dependent upon the degree of endemicity in regions visited, risk behavior, and previous immune status. In endemic areas, the risk to a traveler increases with the length of their stay and with the potential consumption of contaminated foods or beverages.25 The hepatitis A virus (HAV) is highly prevalent in Africa, Greenland, the Middle East, Asia, Indonesia, and Central and South America64 (Table 1). It is intermediately prevalent in Russia and Eastern Europe.25

The risk to nonimmune travelers is 6 to 28/100,000 person-months abroad.65 In 2005, international travel was identified as the most frequent risk factor for HAV infection, and was associated with 15% of adult cases reported to the CDC that year.66

HAV is transmitted through the fecal-oral route by ingestion of contaminated food or water or by close personal contact with infected individuals. Symptoms of acute HAV infection include jaundice, fatigue, abdominal pain, loss of appetite, nausea, diarrhea, and fever.67 Although no chronic infections occur, approximately 15% of patients experience relapses over a 6- to 9-month period.67

Vaccination is the most effective way to prevent the acquisition of HAV (Table 1). Two monovalent vaccines are available. Havrix (GlaxoSmithKline; Rixensart, Belgium) and VAQTA (Merck; Whitehouse Station, NJ) are both inactivated HAV vaccines licensed to be administered in two intramuscular injections. The initial primary dose is followed by a booster dose 6 to 12 months later (up to 18 months later for VAQTA).68,69 In addition, there is a bivalent hepatitis A and B vaccine, Twinrix (GlaxoSmithKline; Rixensart, Belgium), which is administered in three intramuscular injections at 0, 1, and 6 months, or on an accelerated schedule with dosing at 0, 7 and 21 to 30 days, followed with a 12-month booster.70

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Hepatitis B.

The estimated overall risk to the international traveler of acquiring a symptomatic hepatitis B viral (HBV) infection is 1 in 2500 per journey.71 HBV chronic infection prevalence is highest in Africa, Southeast Asia, the Middle East (with the exception of Israel), South and Western Pacific islands, the interior Amazon River basin, and certain parts of the Caribbean25 (Table 1).

HBV is transmitted through contact with the blood of an infected person. This can occur through unprotected sex, contaminated blood products, shared needles with intravenous drug users, and contaminated sharp instruments or exposure to poorly sterilized needles.72 Because of exposure through unprotected sexual contact with local residents, unanticipated medical treatment in facilities where needles may not be properly sterilized, or a contaminated blood transfusion, any traveler may be at risk when visiting a moderate or highly endemic region. Furthermore, certain activities, such as tattooing, intravenous drug use, and acupuncture, increase one's risk of infection.53

Symptoms of acute hepatitis B include jaundice, fatigue, abdominal pain, loss of appetite, nausea and vomiting, and joint pain, and are indistinguishable from those described above for hepatitis A. Nevertheless, approximately 30% of infected individuals are asymptomatic.25,72 This reinforces the importance of vaccinating whenever possible. Left undetected and untreated, chronic infection develops in 6% of individuals over the age of 5. Chronic HBV infection can lead to cirrhosis, liver cancer, and death.25 Approximately 15% to 25% of chronically infected persons die from chronic liver disease.72

Two HBV recombinant DNA vaccines are available: Engerix-B (GlaxoSmithKline; Rixensart, Belgium) and Recombivax HB (Merck; Whitehouse Station, NJ). Both vaccines are administered in three intramuscular injections at 0, 1, and 6 months, and are highly effective and safe.73,74 In addition, travelers who require both HAV and HBV protection can be vaccinated with Twinrix (GlaxoSmithKline; Rixensart, Belgium), the bivalent vaccine (Table 1). Because the HB in Twinrix is less than in the separate B vaccines, it is not recommended for health care workers and others who need optimal protection. However, it is convenient for travelers on tight schedule.

HAV and HBV risks for travelers, consequences of infection, and prevention are discussed in greater detail in additional hepatitis articles in this supplement.

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Other Infections

Although we highlighted some of the more common and/or severe infectious diseases that can be acquired during international travel, the full list of possible infections is quite long, including rabies, rickettsial infections, cholera, giardiasis, infestations (such as bed bugs or fleas), and leishmaniasis. The CDC ( provides comprehensive, up-to-date discussions on all possible infections, as well as associated risks, morbidities and mortalities, and available preventive methods, for all diseases that international business travelers may be exposed to while abroad.25

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Advising the International Business Traveler

It is important for international business travelers to obtain appropriate medical travel advice, including destination-specific disease risks; relevant preventable measures, including vaccinations, prophylaxis, and dietary restrictions; and guidelines regarding the recognition of symptoms and seeking medical assistance while abroad. This advice should come from a physician who is well educated in travel medicine. There is a wealth of information available on the Internet or on off-line computer databases (professional electronic documents) that can readily provide physicians with accurate, up-to-date information on travel medicine. Professional electronic documents can significantly increase a physician's expertise on travel medicine.75,76 In addition, the Infectious Disease Society of America, in conjunction with the International Society for Travel Medicine, provides extensive guidance on the administration of pretravel consultation and posttravel medical care.27 They also provide a thorough review of many health risks to travelers, including those discussed here, and their prevention. Furthermore, the International Society for Travel Medicine provides a complete list of all the Web sites that physicians can access to expand their travel medicine knowledge.27 The CDC also provides a very comprehensive guide to travelers' health, including destination-specific risks, recommended vaccinations, and other prevention measures, primarily through its “Yellow Book” (CDC Health Information for International Travel 2008) which can be purchased or accessed on-line (

An important part of the pretravel consultation is gauging the specific risk to the corporate traveler, which is dependent on accommodations, length of stay, eating behaviors, and behaviors that may increase exposure, such as a day-long hike in the local jungle. For example, there may be different considerations in preventive medicine or vaccine interventions for an executive's short 2-day stay in a five-star hotel who only eats in the hotel, versus a family going overseas for an extended period of time. Nevertheless, unanticipated behaviors or risks, such as an accident, or even behaviors that the traveler will not admit to, must always be considered. Travelers who must be ready to travel on short notice should be prepared well in advance for all likely exposures.

In addition to understanding risk acquisition and prevention, corporate travelers should be provided with a list of safe health care providers or clinics available at their destination(s). Possession of this information can help ensure that, should unanticipated medical treatment be required, individuals can seek care at facilities that have sterile equipment and needles and will provide appropriate diagnostics and treatments. Lists of approved health care facilities can be obtained through the internet. Two examples of such Web sites are and

The impact of acquiring an infectious disease while abroad is not limited to the infected traveler. The risk of reintroducing a disease into the United States is always present. Childhood vaccination programs for HAV and HBV still leave the older population vulnerable to imported infections contracted by family members. Moreover, all US citizens are susceptible to mosquito-borne illnesses, especially in the warmer regions of the country. Corporate medical directors should be aware of the travel plans of employees to ensure that pretravel consultation can be initiated in a timely manner. This could be accomplished by direct communication between those who make travel arrangements and the corporate physician or nurse. For companies that do not have physicians or nurses, that is the majority of US businesses, the responsibility to alert the business traveler to seek pretravel advice can come from the human resource department, company management, or those responsible for making travel decisions. Many companies are now making such consultations a mandatory step in the airline ticket-issuing process. This practice need not be restricted to large companies with in-house health care providers, but can be companies of all sizes. For example, a medium-sized company with its own travel department can withhold issuing airline tickets until a mandatory preventive travel medicine checklist has been completed and verified by a travel medicine physician. Although this may seem like a major obstacle, providing international business travelers with correct advice and proper protection can save businesses and organizations significant amounts of money, time, and productivity lost to illness. As Bunn77 illustrates, it can cost over one-half million dollars when an expatriate becomes ill, whereas thorough vaccination and health care screening before travel can cost approximately $500. Even for companies where travel length is on the scale of a few days or weeks, the cost-effectiveness of pretravel consultation and adherence to preventative recommendations cannot be disputed.

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