INTRODUCTION

Becoming ill far from home is a risk shared by all participants in expeditions. Even though it is impossible to completely eliminate the occurrence of illness, the risk can be reduced through a combination of behavior modification, immunization against vaccine-preventable diseases, and pharmacologic disease prophylaxis. Immunizations are a safe, reliable, and cost-effective component of this three-part approach. With proper preexpedition evaluation and planning, appropriate immunization is often easier and more reliable than behavior modification or pharmacologic disease prophylaxis. Immunizations fall into three categories: routine, required, and recommended.

Routine immunizations are those administered in childhood and/or at regular intervals during adulthood. Measles vaccine and tetanus vaccine are common examples. There is some variation in routine immunizations among countries: as an example, while Bacille Calmette- Guerin (BCG) may be included in the routine immunization schedule in certain areas of the world, it is not in the United States. Similarly, varicella immunization has become part of the routine immunization schedule in the United States but not in other areas of the world. Routine immunizations are listed in Table 4.1.

Required immunizations are those that are necessary for entry into certain countries. Yellow fever vaccine is required for entry into many countries. Meningococcal vaccine is required for entry into Saudi Arabia during the annual Hajj and Umrah pilgrimages. Prior to any expedition, it is important to check updated information about required immunizations for the country or countries of the expedition and those entered in transit.