CDC Yellow Book 2018: Health Information for International Travel

As the number of international travelers and their range of itineraries increases, protecting the health of those travelers and of the communities to which they return has become increasingly challenging. Reliable evidence-based resources to guide decisions around these issues are difficult to find. Further layers of complexity are added by ongoing changes in travel trends, global disease epidemiology, and the tools available to prevent, diagnose, and treat those diseases. The Centers for Disease Control and Prevention Yellow Book 2018: Health Information for International Travel is a comprehensive volume on health issues that international travelers, particularly those departing from and returning to the United States, may encounter. It is published by the US Centers for Disease Control and Prevention (CDC) every 2 years, and it is also available for free online (https://wwwnc.cdc.gov/travel/page/yellowbook-home) and as a mobile app. The chief editors are international leaders in the field of travel medicine; Dr Gary Brunette is the Branch Chief of Travelers’ Health within the CDC, and Dr Phyllis Kozarsky is an infectious disease specialist who has been instrumental in developing international standards in travel medicine knowledge. The long list of contributors includes subject-matter experts from within and outside the CDC. The book is intended for clinicians, including physicians, nurses, and pharmacists, but the editors also suggest its use for the travel industry, volunteer organizations, and individual travelers. This book is divided into 8 chapters consisting largely of text that succinctly summarizes a vast amount of information in a style that is both academic and readable. The text is supplemented by country-specific and disease-specific maps, and by easily interpretable tables and figures that summarize guidelines and recommendations. The 2018 edition differs from the 2016 edition in its inclusion of emerging diseases such as Ebola, Middle East respiratory syndrome, and Zika; new sections on Cuba and Myanmar; and expanded information for specific groups of travelers such as wilderness adventurers, travelers with disabilities, and travelers returning to their home countries. The introduction provides a brief history of the book and useful resources such as the CDC contact information for clinicians and links to the CDC online resources. It also contains the first of several informative and thought-provoking “perspective” pieces, which are essays on a range of topics from “prioritizing care for the resource-limited traveler” to “a history of polio eradication efforts.” The second chapter provides an excellent outline of the key components of a pretravel consultation, with consideration of both the utility and the limitations of such an evaluation. This chapter is a critical component of the book’s appropriate emphasis on preventive medicine. It will be useful in both its specificity and range, including topics such as insect repellant efficacy, water disinfection techniques, medications for altitude sickness, and risks associated with medical tourism. While some of the sections on noninfectious clinical topics, such as deep vein thrombosis and drug interactions, are likely too technical for travelers but too basic for clinicians, they serve as important reminders of issues that may arise. For each of the 76 infectious diseases discussed in chapter 3, there are sections on transmission, epidemiology, clinical presentation, diagnosis, treatment, and prevention of infection. The information is a good overview that is as detailed as space allows. The tables with specific drug and vaccine recommendations are useful references, and clinicians wanting more specific information will find a short bibliography of key references on each infection. The section on country-specific recommendations for yellow fever vaccination and malaria prophylaxis is an excellent resource. The country maps have sufficient resolution to show regional differences in disease risk, and they thus provide actionable information for healthcare practitioners and travelers. Chapter 4 features perspectives on several popular destinations such as the Kilimanjaro region of Tanzania, Machu Picchu, and the Hajj, as well as on a handful of countries that receive high volumes of travelers. The information on the specific sites is useful given the health considerations unique to each one, but the sections on individual countries contain health information that is largely covered in other chapters. Given current world events, readers might instead welcome perspectives on topics such as ways to reduce the risk of harm in areas of political strife, or ways to reduce the heavy footprint of tourism on the environment, or ways to promote the health of impoverished communities that may be encountered while traveling. The brief but excellent chapter 5 is devoted to the post-travel evaluation. Tables on disease incubation periods and on common clinical findings and associated infections are presented. Of particular utility to clinicians evaluating post-travel patients will be the sections on fever, diarrhea, and skin infections. If anything, this chapter could be expanded to include a wider range of clinical syndromes. The section on screening asymptomatic returned travelers, a commonly encountered yet challenging and relatively guideline-free aspect of travel medicine, is outstanding. It offers excellent perspective on the questionable cost-effectiveness of screening such patients, the suboptimal performance of many diagnostic tests, and the unclear benefits of treatment based on certain test results. Chapter 6 addresses transportation issues that are common (health concerns around air travel) and rare (death during travel). Chapter 7 covers many of the same topics covered in earlier chapters but with respect to children. Chapter 8 considers travelers with special needs, such as immunocompromised persons, healthcare workers, and long-term expatriates. This chapter is especially salient as the range of people able and willing to travel expands, and because the health risks that face each population are distinct. Unfortunately, the exclusion of female travelers and elderly travelers from this chapter is an oversight. This book is most suitable for clinicians, who will find it an invaluable resource that addresses most major health risks associated with different types of travel for a wide variety of travelers. It is heavily based on official guidelines and recommendations, evidence in the literature, and expert opinion, and it is remarkably up-to-date. While future editions could rework some of the sections as described above, this is nevertheless an impressively accessible compendium of information that is unparalleled in the travel medicine literature. Potential conflict of interest. Both authors: No reported conflicts. Both authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.