Introduction to Travel Health & the Yellow Book

Travel Health

The number of people traveling internationally has continued to grow substantially in the past decade. According to the World Tourism Organization, there were 1.2 billion worldwide international tourist arrivals in 2015, an increase of 4% from 2013; 50 million more people spent a night at an international destination than in 2014. In 2015, US residents made more than 73 million trips with at least 1 night outside the United States. The importance of protecting the health of individual travelers, as well as safeguarding the health of the communities to which they return, cannot be overstated. 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 preexisting 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. 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 2 primary avenues of communicating CDC’s travel health recommendations.

History and Roles of the Yellow Book

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. 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 at the time of printing, requirements can change. The CDC Travelers’ Health website ( may be checked for regularly updated information to ensure that requirements for international travel are known and met.

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 2018 edition. In addition to the printed copy, a searchable, online version of the Yellow Book can be found on the CDC Travelers’ Health website (

Contact Information for CDC

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 Time (Monday–Friday, closed on holidays) or by visiting to submit your question through an online form.

Pretravel or Post-travel Clinical Questions

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

Because of the complexity of some travel-related diseases, Box 1-1 lists contact information for providers needing clinical assistance.

Box 1-1. CDC contact information for clinicians

CDC-INFO National Contact Center

All topics for clinicians and general public (English and Spanish)

  • 8 am to 8 pm Eastern, M–F: toll-free at 800-CDC-INFO (800-232-4636)
  • E-mail form:

CDC Emergency Operations Center

Emergency or urgent patient care assistance (Note:This line is not intended for use by the general public.)

  • Available 24 hours per day, 7 days per week: 770-488-7100

CDC Drug Service

Distribution of special biologic agents and drugs

Chikungunya, Japanese Encephalitis, Tickborne Encephalitis, and Yellow Fever

Assistance with diagnostic testing for these diseases and for questions about antibody response to yellow fever vaccination

  • Division of Vectorborne Diseases, 8 am to 4:30 pm Mountain, M–F: 970-221-6400
  • Viral Special Pathogens Branch can also assist for tickborne encephalitis, 8:30 am to 5:30 pm Eastern, M–F: 404-639-1115
  • After hours/weekends/holidays: 770-488-7100
  • State or local health departments may be able to assist:


Dengue diagnostic testing assistance

Malaria Hotline

Assistance with diagnosis or management of suspected cases of malaria

  • 9 am to 5 pm Eastern, M–F: 770-488-7788 or toll-free at 855-856-4713
  • Emergency consultation after hours/weekends/holidays: 770-488-7100, ask for a Malaria Branch clinician

Parasitic Diseases (other than malaria)


Assistance with evaluation and treatment of patients suspected to have a parasitic disease

  • 8 am to 4 pm Eastern, M–F: 404-718-4745
  • Emergency consultation after hours/weekends/holidays: 770-488-7100, ask for an on-call clinician in Parasitic Diseases
  • E-mail:


Online parasitic diseases diagnostic assistance service for laboratorians, pathologists, and other health professionals

Rickettsial Diseases

Diagnostic and treatment assistance

  • 8 am to 4:30 pm Eastern, M–F: 404-639-1075
  • Emergency consultation after hours/weekends/holidays: 770-488-7100, ask for an on-call clinician in Rickettsial Diseases

Viral Hemorrhagic Fevers


Consultation for diagnosis and reporting suspected cases in or requiring evacuation to the United States

  • 8:30 am to 5:30 pm Eastern, M–F: 404-639-1115
  • Emergency consultation after hours/weekends/holidays: 770-488-7100


Requests for ribavirin through the Food and Drug Administration (FDA) from Valeant Pharmaceuticals

  • Providers should request through FDA at 301-736-3400
  • Simultaneously notify Valeant at 800-548-5100, ext. 5 (domestic) or 949-461-6971 (international)


  1. United Nations World Tourism Organization. UNWTO World Tourism Barometer, Vol. 14 (March). Madrid: United Nations World Tourism Organization; 2016 [cited 2016 Mar. 2]; Available from:
  2. US Department of Commerce, Office of Travel and Tourism Industries. 2015 Monthly US Outbound Air Travel to International Regions. Washington, DC: US Department of Commerce; 2016 [cited 2016 Mar. 21]; Available from:
  3. World Health Organization. International Health Regulations (2005). Geneva: World Health Organization; 2008 [cited 2016 Apr. 11]; 2nd: Available from:


Phyllis E. Kozarsky