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Chapter 1 Introduction

Introduction to Travel Health & the Yellow Book

Amanda Whatley Lee, Phyllis E. Kozarsky


The number of people traveling internationally has continued to grow substantially in the past decade. According to the World Tourism Organization (WTO), there were an estimated 990 million international tourist arrivals in 2011 throughout the world. In 2010, US residents made nearly 60 million trips with at least 1 night outside the United States. International travel takes on many forms, including tourism, business, study abroad, research, visiting friends and relatives, ecotourism, adventure, medical tourism, mission work, and responding to international disasters. Travelers are as unique as their itineraries, covering all age ranges and having a variety of health concerns and conditions. The infectious disease risks that travelers face are dynamic—some travel destinations have become safer, while in other areas, new diseases have emerged and other diseases have reemerged.

The risk of becoming ill or injured during international travel depends on many factors, such as the region of the world visited, a traveler’s age and health status, the length of the trip, and the diversity of planned activities. The Centers for Disease Control and Prevention (CDC) provides international travel health information to address the range of health risks a traveler may face, with the aim of assisting travelers and clinicians to better understand the measures necessary to prevent illness and injury during international travel. This publication and the CDC Travelers’ Health website ( are the 2 primary avenues of communicating CDC’s travel health recommendations.


CDC Health Information for International Travel (“The Yellow Book”) has been a trusted resource since 1967. Originally, it was a small pamphlet published to satisfy the International Sanitary Regulations’ requirements and the International Health Regulations (IHR), adopted by the World Health Organization (WHO) in 1951 and 1969, respectively; the IHR were completely revised in 2005. The purpose of the IHR is to ensure maximum security against the international spread of diseases, with minimum interference with world travel and commerce. A copy of the current IHR and supporting information can be found on the WHO website (

In addition to reporting public health events of international concern, the United States must also inform the public about health requirements for entering other countries, such as the necessity of being vaccinated against yellow fever. Some countries require all travelers to have an International Certificate of Vaccination or Prophylaxis (ICVP) documenting yellow fever vaccine administration as a condition for entry, while other countries require vaccination against yellow fever only if travelers arrive from a country where the yellow fever virus is known to circulate. The Yellow Book and the CDC Travelers’ Health website aim to communicate these requirements under the IHR (2005). Although this publication includes the most current available information, requirements can change. Current information must be accessed to ensure that these requirements are met; the CDC Travelers’ Health website ( may be checked for regularly updated information.

The Yellow Book is written primarily for clinicians, including physicians, nurses, and pharmacists. Others, such as people in the travel industry, multinational corporations, missionary and volunteer organizations, and individual travelers, can also find a wealth of information here.

This text is authored by subject-matter experts from within CDC and outside the agency. The guidelines presented in this book are evidence-based and supported by best practices. Internal text citations have not been included; however, a bibliography is included at the end of each section for those who would like to obtain more detailed information. The CDC Travelers’ Health program and the CDC Foundation are pleased to partner with Oxford University Press, Inc., to publish the 2014 edition. In addition to the printed copy, a searchable, online version of the Yellow Book can be found on the CDC Travelers’ Health website (


The Yellow Book reflects the ever-changing nature of travel medicine. Each new edition notes the changes in global disease distribution, vaccine and medication guidelines, and new developments in preventing travel health risks.

Some new sections in this edition include sections covering Travel Medicine Data Collection: GeoSentinel & Global TravEpiNet (later in this chapter) and Last-Minute Travelers (Chapter 8). In addition, sections such as Escherichia coli, Fascioliasis, and Salmonellosis (Nontyphoidal) have been added to the diseases covered in Chapter 3, while Cambodia: Angkor Wat, Thailand, and Vietnam have been added to the select destinations included in Chapter 4.

In addition to the country-specific yellow fever vaccine requirements and recommendations and malaria transmission information and prophylaxis recommendations, other country-specific vaccine recommendations have been added to the section located at the end of Chapter 3.

Perspectives Editorial Sections

A continuing feature from previous editions is the incorporation of editorial sections entitled Perspectives. Some new Perspectives sections include Prioritizing Care for the Resource-Limited Traveler (Chapter 2), Terrorism (Chapter 2), and Malaria in Long-Term Travelers & Expatriates (Chapter 8). Although the body of evidence-based knowledge in the field of travel medicine is growing, there is recognition that the practice of this specialty involves not only science, but art as well. Thus, readers will notice a few sections that contain editorial discussions aiming to add depth and clinical perspective, as well as to discuss some controversies or differences in opinions and practice. Perspectives sections reflect the views and opinions of the authors and do not necessarily represent official CDC recommendations.

Historical Editorial Sections

Four new sections encompass the 2014 debut of a new category of historical editorial sections, entitled For the Record. Learning the background of certain clinical practices can give readers a better understanding of the health topic and prevention or treatment recommendations. Beyond the practical reasons, these sections are included because the editorial team thought they would be interesting for inquisitive readers.


Questions, comments, and suggestions for CDC Travelers’ Health, including comments about this publication, may be made through the CDC-INFO contact center, toll-free at 800-CDC-INFO (800-232-4636) 8 am to 8 pm Eastern (Monday–Friday, closed holidays) or by visiting and clicking on “Contact CDC-INFO” to submit your question through an online e-mail form.

Pre-Travel or Post-Travel Clinical Questions

Since CDC is not a medical facility, clinicians needing assistance with patients who are preparing for travel should consider referral to a travel clinic or a clinic listed on the International Society of Travel Medicine website (

Clinicians with post-travel health questions regarding their patients may consider referral to a clinic listed on the ISTM website, the American Society of Tropical Medicine and Hygiene website (, or a medical university with specialists in infectious diseases.

Malaria: Because of the clinical complexity of malaria, the CDC Malaria Branch offers clinicians assistance with the diagnosis or management of suspected cases of malaria. Clinicians can contact CDC’s Malaria Branch telephone hotline during business hours at 770-488-7788 or toll-free at 855–856-4713. After hours and on weekends and holidays, a Malaria Branch clinician may be reached by calling 770-488-7100.

Other parasitic diseases: CDC has an online diagnostic assistance service, called DPDx, for laboratorians, pathologists, and other health professionals (see Additionally, clinicians may consult with CDC about evaluation and treatment of patients suspected to have a parasitic disease (404-718-4745;

Yellow fever: Clinicians should contact their state or local health department or call 970-221-6400 for assistance with diagnostic testing for yellow fever infections and for questions about antibody response to vaccination.

CDC Emergency Operations Center: CDC maintains an Emergency Operations Center to assist local, state, and federal agencies (770-488-7100) 24 hours per day, 7 days per week. Assistance can also be given to health care providers with questions on emergency or urgent patient care. Note: this line is not intended for the general public.

All other questions for CDC may be directed to the CDC INFO contact center, toll-free at 800-CDC-INFO (800-232-4636) 8 am to 8 pm Eastern (Monday–Friday, closed holidays) or


  1. United Nations World Tourism Organization. UNWTO World Tourism Barometer, Vol. 10 (September). Madrid: United Nations World Tourism Organization; 2012 [cited 2012 Sep 25]. Available from:
  2. US Department of Commerce, Office of Travel and Tourism Industries. 2011 United States resident travel abroad. Washington, DC: US Department of Commerce; 2012 [cited 2012 Sep 25]. Available from:
  3. World Health Organization. International Health Regulations (2005). 2nd ed. Geneva: World Health Organization; 2008 [cited 2012 Sep 25]. Available from: