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Travel medicine and ID: Partners in an era of frequent global movement
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Travel history has a profound and essential role for the infectious disease clinician and for promoting public health priorities. The patient’s lifetime of geographic exposures, and especially those in the most recent few months, will determine what potential diagnoses are included in the differential diagnosis, whether caring for a patient with a fever, a skin lesion, a pulmonary infiltrate, focal neurologic lesion or other problem. A person’s geographic exposure profile must be combined with the clinician’s knowledge (or access to information) about clinical presentations, incubation periods, frequency of occurrence, and geographic distribution of dozens of common and a few hundred uncommon infections.
Today, complex geographic exposure histories are commonplace — and infectious disease clinicians must be prepared to interpret their relevance for a current illness. We are witnessing a continued growth in the volume of international travelers and migratory populations who have the potential to carry pathogens from their point of origin to distant locations and home again. Travelers can also pick up myriad organisms en route and share them along their journeys. Migration, tourism, commerce, research and education weave a dense network of connections between and among different world regions. High-impact infectious disease outbreaks such as Ebola and Zika have surfaced unexpectedly, disseminated rapidly and challenged our health systems to control them. “Old” disease threats such as yellow fever and malaria have demonstrated their ability to resurge or evolve. The emergence and international spread of multiply resistant microbes has also become an urgent worldwide concern.
Fortunately, we have much better tools at our disposal today than in past decades. The GeoSentinel Surveillance network for over 20 years has systematically collected data on ill travelers, which allows the linking of specific places with specific diseases. The International Society of Travel Medicine, through its activities (regular conferences and courses, support of research activities, dissemination of knowledge and discoveries through its journal, webinars, guidelines and other activities), has helped to establish an evidence base for travel medicine. What are the risks? What preventive strategies work? How can we recognize, diagnose and treat common and unusual infections related to travel? Which individuals or groups are most vulnerable? What is the potential impact of these risks on public health and how can we help to mitigate the impact? Regularly updated information is also available through the CDC’s Travelers’ Health website and in the Yellow Book (www.cdc.gov/travel and https://wwwnc.cdc.gov/travel/yellowbook/2018/table-of-contents).
Prevention of travel-associated diseases can modify the microbial burden that moves and returns with travelers. For instance, it has been shown that travelers who experience diarrhea and use antibiotics are more likely to develop carriage of multidrug-resistant organisms. If we can lower antibiotic use by reducing the occurrence of travelers’ diarrhea and by curtailing unnecessary treatment, we may potentially minimize the spread of resistant microbes and resistance genes. Similarly, a traveler who receives treatment or is hospitalized abroad may become infected or colonized with multiply resistant microbes — or they may share personal microbial flora with the local environment. Hence, infectious disease clinicians and public health professionals must recognize the history of health care abroad as a risk for acquiring multiply resistant microbes that may differ from the home environment.
Knowledge of travel medicine and vaccines and malaria chemoprophylaxis used to protect travelers is essential for infectious disease clinicians who need to have (or know where to find) updated information, including the global distribution of infections. Infectious disease clinicians are an integral part of the first-line response in identifying infections of public health importance — from measles to Ebola — and notifying the appropriate entity to allow prompt diagnosis and response, to prevent spread, or to identify contacts. Knowledge of travel medicine provides crucial background on the translocation of infectious diseases and its impact on the individual traveler and on the public health system.
- For more information:
- Lin H. Chen, MD, FACP, FASTMH, FISTM, is director of the Travel Medicine Center at Mount Auburn Hospital and an associate professor of medicine at Harvard Medical School.
- Mary Elizabeth Wilson, MD, FIDSA, FACP, FASTMH, FISTM, is adjunct professor of global health and population at the Harvard T.H. Chan School of Public Health, and a clinical professor of epidemiology and biostatistics at the University of California, San Francisco.
Disclosures: Chen and Wilson report no relevant financial disclosures.