Introduction
International travel continues to grow substantially with each passing year, including travel to developing areas of the world that once were rarely visited. As air travel has become more affordable, increasing numbers of people from all walks of life are seeing the world, some venturing abroad for the first time. These travelers can range in age from very young infants and small children to octogenarians; they may have pre-existing medical conditions or may be pregnant or contemplating pregnancy. Additionally, the purposes for international travel today are varied and, in addition to tourism, can include business, study, visiting friends and relatives, or responding to an international disaster.
In general, the risk of becoming ill during international travel depends on the region of the world visited, as well as factors such as age, health status, length of stay, and planned activities. Travelers may be at risk for injuries, especially if engaging in risky recreational activities. New or reemerging infectious diseases may pose a danger if a traveler is exposed.
To provide standard recommendations for health maintenance and prevention of illness among US travelers, Health Information for International Travel (“The Yellow Book”) has been a trusted resource over the years for health-care providers and travelers alike. As with previous editions, the 2008 edition of the Yellow Book covers new and updated vaccine guidelines and new developments in the prevention and treatment of malaria and other health risks. With each edition, the scope is broadened to address emerging travel health issues. For example, included in the 2008 edition is a substantially enhanced chapter on influenza that covers avian influenza and the threat of pandemic influenza. Because new vaccines and recommendations have been developed, information about diphtheria, tetanus and pertussis has been separated into three chapters. New chapters of the book include skin and soft tissue infections and deep vein thrombosis/pulmonary embolism; sections have been added on health risks for humanitarian workers and the differing responsibilities that the clinician, traveler, and travel industry each have in providing and obtaining the best information on health risks abroad. As with previous editions, the text has been authored by subject-matter experts both within CDC and outside the agency. The guidelines presented in this book are evidence-based and supported by best practices. References are included for those who would like to obtain more detailed information.
The Yellow Book is produced by the Division of Global Migration and Quarantine, National Center for Preparedness, Control, and Detection of Infectious Diseases, Centers for Disease Control and Prevention (CDC). The 2007-2008 edition is the second edition to be published by Elsevier publishing house, publishers of numerous authoritative texts on infectious diseases and travel medicine.
Although the “Yellow Book” is written primarily for health-care providers, including physicians, nurses, and pharmacists, others (the travel industry, multinational corporations, missionary and volunteer organizations, and individuals and families who vacation abroad) can all find a wealth of information within this text.
Pre-Travel Health Measures
To reduce the risk of illness or injury abroad, a health-care provider should be consulted, ideally 4-6 weeks before international travel. Even if travel is imminent, some vaccine schedules may be accelerated to provide protection, and information to reduce health risk could still be beneficial. In general, an individualized assessment to determine the risk of illness considers any underlying medical problems, previous vaccinations, adverse events and allergies, current prescription and over-the-counter medications, and previous travel. Additionally, children, the elderly, pregnant women, and immunocompromised travelers may be particularly vulnerable to certain problems while traveling and may require more specialized counseling. Adventure travelers may also need additional vaccines and protective measures.
During the pre-travel health visit, the health-care provider should also update the patient on routine vaccinations as needed, such as diphtheria/tetanus and measles, mumps, and rubella. Other vaccines that may be recommended include pertussis, polio, hepatitis A, hepatitis B, varicella, Japanese encephalitis, meningococcal meningitis, rabies, yellow fever, and typhoid. For diseases for which no vaccines are available, such as dengue, specific preventive measures or medications are detailed in this book.
To assess the patient thoroughly, the health-care provider must consider the entire itinerary; the destination city, town, or village; the style of travel; the length of stay; the season of the year; potential exposures; and current outbreaks. Travelers to low-income or developing countries are at greater risk than those who travel to developed countries (e.g., Canada, Australia, New Zealand, Japan, and Western Europe), where health risks are similar to those found in United States. Travelers visiting urban tourist areas and staying in first-class accommodations may have a lower risk for exposure to infectious diseases.
Basic protective measures should also be emphasized during the office visit, such as frequent handwashing, food and water precautions, the use of sunscreen and sun shades where appropriate, and the prevention of insect bites if visiting tropical areas of the world. This advice can be reinforced with brochures or similar printed material that can be given to the patient.
For more complicated travel itineraries or for the traveler with multiple medical problems, referral to a travel health specialist is advisable. In addition, yellow fever vaccine can only be administered by authorized providers.
Travelers should recognize that by protecting their health they are also potentially protecting others from infection. Additionally, by respecting the culture and environment in areas they visit, travelers can contribute to the preservation of both. The goal of CDC’s travel health information is to 1) help individuals enjoy their international travels safely and 2) assist health-care providers in deciding on the vaccines, medications, and other measures necessary to prevent illness and injury in travelers.
Other Sources of Travel Health Information from CDC
- CDC Travelers’ Health website, www.cdc.gov/travel, includes current travel health information about disease outbreaks that might impact travelers; vaccine requirements and recommendations; medications for the prevention and treatment of common travel-related problems; health recommendations for travel by cruise ship and air; and links to information about specific diseases. In addition, there are valuable links to other websites, such as the World Health Organization, the Pan American Health Organization, and the U.S. State Department, as well as state and local health departments.
- Yellow Book online: The searchable online version of the “Yellow Book” can be found on the CDC Internet website at http://wwwn.cdc.gov/travel/contentYellowBook.aspx and also can be accessed through the CDC Travelers’ Health website.
- Travelers’ Health Electronic Mail: E-mail queries, comments, and suggestions for CDC Travelers’ Health, including comments about this book, may be made through the CDC Travelers’ Health website. Urgent health questions from the public should be directed to a health-care provider, and questions from health-care providers should be directed to the local or state health department.
- Malaria Information: CDC’s Malaria Branch publishes a brochure (Preventing Malaria in Travelers), and posters which can be accessed and downloaded from the CDC Travelers’ Health website http://www.cdc.gov/travel/diseases.htm#malaria. In addition, health-care providers needing assistance with the diagnosis or management of suspected cases of malaria can contact CDC’s Malaria Branch Telephone Hotline at 770-488-7788 during business hours. After hours and on weekends, a Malaria Branch clinician may be reached by calling 770-488-7100.
- CDC Yellow Fever Vaccine Registry: http://www2.ncid.cdc.gov/travel/yellowfever/. This on-line registry, which is hosted from the CDC’s Travelers’ Health website, includes a directory of yellow fever vaccination providers throughout the 60 US states, territories and the District of Columbia. State health departments are also able to update their information on the Registry from this site.
- National Immunization Program (NIP): www.cdc.gov/vaccines. CDC’s vaccine program provides information on their website about current Advisory Comittee on Immunization Practices (ACIP)-recommended vaccine schedules for adults and children, and links to the Vaccine Adverse Event Reporting System (VAERS).
Additional Sources of Travel Health Information
- The International Society of Travel Medicine (ISTM): www.istm.org. The ISTM website contains a list of travel health clinics both in the United States and worldwide. The ISTM primarily focuses on pre-travel health education and migration medicine.
- The American Society of Tropical Medicine and Hygiene (ASTM&H): www.astmh.org The ASTMH website includes a directory of clinicians, primarily within the United States, who specialize in clinical tropical medicine and travelers’ health. These health-care providers are available for evaluation of returning travelers who are ill.
- The World Health Organization (WHO): www.who.int. The WHO website provides global health information and links to various other international sites. It also includes WHO’s online travel health information, entitled International Travel and Health. In some instances, travel health recommendations from WHO may vary from CDC guidelines. Variability in access to different vaccines and drugs, as well as some differences in expert opinion regarding the prevention of illness, may contribute to the occasional differences.
- The Pan American Health Organization (PAHO): www.paho.org. PAHO is a regional office of WHO. For travelers visiting countries in the Western Hemisphere, the PAHO website includes information about some outbreaks, disease trends, country-specific health statistics, and disease control efforts in the Americas.
- The U.S. State Department: www.state.gov/travel. This website provides information for Americans overseas, including travel warnings, emergencies, crisis awareness and preparedness, consular information, and special services. Medical information for Americans traveling overseas will be found at www.travel.state.gov/travel/tips/health/health_1185.html. The website also provides a secure online travel registration site for American citizens to record information about their trip abroad so the State Department can provide assistance in the case of an emergency: https://travelregistration.state.gov/ibrs/.
- U.S. Central Intelligence Agency (CIA): The CIA website (www.odci.gov/cia/publications/pubs; select World Factbook) contains useful information for travelers.
- The official US government website for pandemic influenza (http://www.pandemicflu.gov/) provides information about preparedness and response to an influenza pandemic.
- The World Organization for Animal Health (OIE) website (http://www.oie.int/eng/en_index.htm) contains information about disease outbreaks in animals that might impact travelers, such as avian influenza.
In addition to those listed above, a number of reputable commercial travel health information resources may be accessed through health-care providers who subscribe to them.
The WHO International Health Regulations (IHR)
The purpose of the WHO IHR is to ensure maximum security against the international spread of diseases, with minimum interference with world traffic. Epidemics have been catalysts for intensive multilateral cooperation in public health. In 1948, the WHO constitution came into being, and the first International Sanitary Regulations were adopted in 1951. These were renamed the International Health Regulations in 1969; they were modified in 1973 and 1981 and revised in May 2005.
The IHR were originally intended to help monitor and control six serious infectious diseases: cholera, plague, yellow fever, smallpox, relapsing fever, and typhus. Today, only cholera, plague and yellow fever are notifiable diseases. In addition to the three standard diseases, the IHR (2005), which go into effect in 2007, stipulate communication regarding events which constitute a public health risk to other states through the international spread of disease and potentially require a coordinated international response. This definition broadens the scope of the IHR (1969) to cover existing, new and reemerging diseases, including emergencies caused by noninfectious disease agents. As a member state of the WHO, the United States adheres to the IHR and participates in their development.
Most immunizations are not required under the IHR but may be recommended to protect the health of the traveler. However, an International Certificate of Vaccination against yellow fever is required by some countries as a condition for entry, while other countries require vaccination against yellow fever only if travelers arrive from a country where the disease is present. Because requirements can change, current information must be taken into consideration. Although this text includes the most up-to-date information regarding these requirements at publication, the Travelers’ Health website may be accessed for additional information.
