Sources of Information

The Centers for Disease Control and Prevention (CDC) publishes several authoritative sources of information on travel medicine. Health Information for International Travel (the “yellow book”) is updated annually. Two other periodicals, the weekly Morbidity and Mortality Weekly Report (MMWR) and Summary of Health Information for International Travel (the “blue sheet,” published biweekly), provide updated information on the status of immunization recommendations, worldwide disease outbreaks, and changes in health conditions. A reliable way to obtain current travel health information, including vaccine requirements, malaria chemoprophylaxis, and disease outbreaks for various regions of the world, is to consult the CDC Travelers’ Health website at http://wwwnc.cdc.gov/travel/. See Chapter 49 for more information on immunizations for travel. For nonmedical information of interest to the traveler, the U.S. State Department can be accessed at http://travel.state.gov/. Additional resources for travel medicine information are listed at the end of the chapter.

Aside from traveler’s diarrhea (see Chapter 44), traffic-related accidents, and purified protein derivative conversion, the major travel-acquired illnesses in descending order from most to least common are as follows:

These disorders are often preventable if the traveler takes specific precautions or prophylactic agents. Influenza, acute HIV infection, Legionella, and poliomyelitis are not discussed in this chapter because they are generally preventable with standard immunizations, or their medical management is similar to that in developed countries. Travelers at risk for HIV exposure should consider bringing 72 hours of postexposure prophylaxis medication, because many developing countries do not have access to HIV drugs.

Malaria

See Chapter 47.

Dengue Fever

Dengue virus is a single-stranded ribonucleic acid (RNA) flavivirus that is transmitted by the day-biting urban mosquito Aedes aegypti or the jungle mosquito Aedes albopictus. A. aegypti is the principal vector for dengue viruses worldwide. Viral transmission is maintained through a mosquito-human cycle without a major animal reservoir.

Yellow Fever

Yellow fever is one of the viral hemorrhagic fevers. It is caused by a single-stranded RNA flavivirus that is transmitted by mosquitoes. The liver is the principal target organ. All recent cases of American yellow fever were acquired in the jungle environment; however, urban transmission continues to occur in Africa.

Rabies Exposure

Rabies exists almost everywhere in the world with the exception of Antarctica and a few island nations. Most cases of human disease in the developing world result from multiple, deep bites to the face, scalp, or upper extremities from an unimmunized canine. In more developed countries, however, the majority of rabies transmission occurs from wild animal carriers (see Chapter 42). Travelers who plan on spending more than 1 month in regions at high risk for rabies should consider preexposure rabies immunization. CDC recommendations for rabies prophylaxis can be found at http://www.cdc.gov/diseases/rabies.html. Rabies is almost universally fatal within a few weeks of symptom onset. If a potential rabies exposure occurs, immunized patients will require only two subsequent rabies immunization boosters on days 0 and 3 post exposure with close follow up. Patients without preexposure immunizations should receive rabies immune globulin and rabies immunization as outlined in Chapter 43.

Hepatitis Viruses

The causes of hepatitis may be divided into two groups. First, the lettered viruses now include hepatitis A to G. These are associated with defined clinical syndromes and elevated liver function test results. Second, other organisms that cause hepatitis as part of a more systemic infection include Epstein-Barr virus, cytomegalovirus, toxoplasmosis, and leptospirosis.