International travel exposes people to health risks that they do not encounter in the United States because of a greater number of infectious diseases and diseases that do not exist in this country. A thorough, systematic approach to the needs of the international traveler can prevent illness in the individual and contribute to controlling the spread of nonendemic diseases to the greater population.

Immunizations are so effective that, in what was perhaps the greatest public health initiative the world has ever seen, broad administration of the smallpox vaccine eradicated the disease from the human population. The last reported case of endemic smallpox occurred in Somalia in October 1977. In 1988, the World Health Organization, with similarly high goals, adopted a resolution to eradicate poliomyelitis from the world by the year 2000. Thus far, the last case of wild poliovirus infection reported in the Western Hemisphere was more than 5 years ago.<sup>3 Centers for Disease Control Certification of poliomyelitis eradication—The Americas MMWR 1994 ;  43 : 720-722

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Immunization programs, however, have also proved their vulnerability. In 1983, the United States had the lowest number of measles cases ever reported: fewer than 1500. In 1990, the number of cases reported rose to over 27,700.<sup>5   Centers for Disease Control Immunization Information from the CDC :  (1995). 

Cliquez ici pour aller à la section Références</sup> This breakthrough is blamed on decreased herd immunity owing to decreased childhood immunization rates, as well as a less immunogenic vaccine antigen before 1980.

Although immunizations are important and effective, the overall approach to the international traveler must be a comprehensive travel medical consult, consisting of a complete history, focused physical examination, and traveler education stressing the imperatives of insect avoidance, food and water precautions, diarrhea management, a travel medicine kit, and immunization needs. Specific “wilderness medicine” advice regarding high altitude, diving, or hostile environments should be addressed as appropriate. Many of the illnesses that affect travelers, such as travelers' diarrhea, are not prevented by “shots,” but immunizations can and do protect people from many potentially life-threatening illnesses.

There is an understanding, particularly in travel medicine, that a balance must be reached between the risks and benefits of immunizations; in the grander scheme, the cost could also be added to the assessment. A prime example is the use of typhoid vaccines: the risk to travelers is estimated to be 1 in 10 million in travelers to Europe and up to 1 in 10,000 if visiting family, friends, or relatives in India, Pakistan, or Peru.<sup>18 Kozarsky P. Maximum immunization for travel: Con Journal of Travel Medicine 1995 ;  2 : 186-191

Cliquez ici pour aller à la section Références</sup> Currently, it costs approximately $300,000 to prevent one case of typhoid illness in US travelers.<sup>1 Behrens R., Roberts J. Is travel prophylaxis worthwhile? Economic appraisal of prophylactic measures against malaria, hepatitis A and typhoid in travelers BMJ 1994 ;  309 : 918-922

Cliquez ici pour aller à la section Références</sup> Thus, the health care provider should use discretion and consider carefully the actual benefit of protection versus cost and the risk of potential side effects when recommending immunizations.

The travel medicine consult and the delivery of vaccines should ideally begin 4 to 8 weeks before departure. A systematic six-step approach, as outlined in this article, will help the provider identify the immunization needs of the individual traveler. Immunization indications can be divided into the six categories listed below (Figure 1).

A comprehensive list of immunizations for travelers is included in Table 3.