Chapter 156

The popularity of transcontinental travel allows even exotic destinations to be reached within 36 hours. Greater numbers of immunologically naïve travelers venture abroad each year, and many travelers visit tropical nations where illness burden is largely due to poverty, civil unrest, poor environmental hygiene, malnutrition, and tropical illnesses.1 Many returning travelers have neither serious nor exotic illnesses. The likely causes of acute symptoms are common problems such as upper respiratory infections, diarrheal illnesses, or reactions to stress, fatigue, or new medications. The ED physician often does not confirm the final diagnosis, but rather protects the health of the public from potentially communicable diseases, begins diagnostic and therapeutic interventions, and provides appropriate referral. Local or regional international health clinics are good resources for referral of patients who need more advanced evaluation, serologic testing, and long-term follow-up (see http://www.travelersvaccines.com/en/clinics/clinic_locator.cfm).

### Individuals at Risk

Sixty-four percent of travelers report one or more illnesses during travel, 26% are ill upon return, and 56% of those ill upon return develop symptoms after arrival in the U.S.2 Many disease incubation times are longer than the transit times of most modern travelers.

Travelers are at risk for certain infectious diseases based on the duration of travel, endemic exposure, and preexisting immunity. Most travelers on vacation or business are abroad for <20 days, and <5% spend extended time overseas. Some travelers originate from disease-endemic nations, as tourists or newly arrived immigrants seeking U.S. domicile. Such visitors and foreign nationals are at risk for typical infectious diseases and newly emerging infections. Others at risk include nonvoluntary travelers, such as refugees and displaced persons, as well as landed immigrants with permanent U.S. residence who are returning from visiting their homeland. A high degree of clinical suspicion is warranted for this latter group because many presume they still have acquired immunity for diseases such as malaria, but remain susceptible to endemic illnesses. Western travelers also have an increasing risk of tropical illness as a result of increasing exotic adventure-type travel to remote locales that were previously inaccessible (Table 156-1).

Table 156-1 Overall Risk of Exposure to Infectious Agents

Many travelers are exposed to diseases such as Plasmodium falciparum (malaria) that are uncommon in the U.S., but which are leading causes of mortality overseas. Other parasitic agents, such as helminths and rickettsia, also occur with increased frequency and severity in the tropics (see Chapter 153, Malaria, and Chapter 155, Zoonotic Infections). Diagnosis of a tropical infection requires a unique set of tests, and therapy is organism specific. Also, suspect the potential for a bioterrorist agent as a cause of disease, when plausible. Factors suggesting intentional releases include divergence of the disease presentation from the typical epidemiology of the community and an atypical number of patients presenting with similar clinical syndromes. Examples of diseases that could be weaponized include anthrax, plague, viral hemorrhagic fevers, and tularemia (see Chapter 10, Bioterrorism Recognition and Response: Implications for the Emergency Clinician, and Chapter 155, Zoonotic Infections).

### History

Suspect imported disease in ...

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