General Approach to the Returned Traveler

As with any medical evaluation, the chief complaint and associated clinical factors are the first things to consider when approaching an ill returned traveler. Within this context, the severity of illness is not only important for patient triage but can help clinicians distinguish certain infections from one other. Is the traveler hemodynamically stable? Is the infection potentially life-threatening, such as malaria? Does the traveler have a severe respiratory syndrome or signs of hemorrhagic fever? Some suspected illnesses may also necessitate prompt involvement of public health authorities. See “Management” below for more details.

The itinerary and activities in which the traveler participated are crucial to formulating a differential diagnosis, because potential exposures differ depending on the region of travel and behaviors. A febrile illness with nonspecific symptoms could be malaria, dengue, typhoid fever, or rickettsial disease, among others. Being able to exclude certain infections will avoid unnecessary testing. A 2013 study from the GeoSentinel Surveillance Network found that the frequency of certain diseases varied depending on the region of the world visited; among travelers with fevers, malaria was diagnosed most frequently among travelers returning from Africa, while dengue was diagnosed most frequently among travelers from Asia. The duration of travel is also important, since the risk of a travel-related illness increases with the length of the trip. A tropical medicine specialist can assist with the differential diagnosis and may be aware of outbreaks or the current prevalence of an infectious disease in an area. The 2014–2015 Ebola virus epidemic in West Africa highlighted the importance of epidemiologic factors and travel itineraries in managing patients and protecting staff and the community.

Because most common travel-related infections have short incubation periods, a majority of ill travelers will seek medical attention within 1 month of return from their destination. Travelers’ diarrhea, dengue, other arboviral infections, and influenza are examples of infections with shorter incubation periods (<2 weeks). Those with slightly longer incubation periods, up to 4–6 weeks, include malaria, typhoid fever, acute HIV, viral hepatitis, and leishmaniasis, among others. Occasionally, however, infections such as malaria, schistosomiasis, leishmaniasis, or tuberculosis can manifest months or even years later. In particular, malaria should be considered in the differential diagnosis of any traveler who traveled to a malaria-endemic area within a year of presentation. Therefore, a detailed history that extends beyond a few months before presentation can be helpful. The most common travel-related infections by incubation period are listed in Table 11-1.

Comorbidities can affect the susceptibility to infection, as well as the clinical manifestations and severity of illness. An increasing number of immunosuppressed people (due to organ transplants, immune-modulating medications, HIV infection, or other primary or acquired immunodeficiencies) are international travelers (see Chapter 8, Immunocompromised Travelers). In addition, a number of factors associated with travel can increase the likelihood of exacerbations of chronic conditions during or following travel such as ischemic heart disease, inflammatory bowel disease, or chronic lung disease.

The history of vaccinations and malaria prophylaxis should be reviewed when evaluating an ill returned traveler. Fewer than half of US travelers to developing countries seek pretravel medical advice and may not have received vaccines or taken antimalarial drugs. Although adherence to malaria prophylaxis does not rule out the possibility of malaria, it reduces the risk and increases the likelihood of an alternative diagnosis. Fever and a rash in a traveler without measles vaccination would raise concern about measles. The most common vaccine-preventable diseases among returned travelers seeking care at a GeoSentinel clinic between 1997 and 2010 included typhoid fever, hepatitis A, hepatitis B, and influenza. More than half of these patients with vaccine-preventable diseases were hospitalized.

Knowledge of the patient’s exposures during travel, including insect bites, contaminated food or water, or freshwater swimming, can also assist with the differential diagnosis. In addition to malarial parasites, mosquitoes transmit viruses (such as dengue, yellow fever, chikungunya, and Zika) and filarial parasites (such as Wuchereria bancrofti ). Depending on the clinical syndrome, a history of a tick bite could suggest a diagnosis of tickborne encephalitis, African tick-bite fever, or other rickettsial infections. Tsetse flies are large, and their bites are painful and often recalled by the patient. They can carry Trypanosoma brucei , the protozoan that causes African sleeping sickness. Freshwater swimming or other water contact can put the patient at risk for schistosomiasis, leptospirosis, and other diseases.

Types of accommodations and activities can also influence the risk for acquiring certain diseases while abroad. Travelers who visit friends and relatives are at higher risk of malaria, typhoid fever, and certain other diseases, often because they stay longer, travel to more remote destinations, have more contact with local water sources, and do not seek pretravel advice (see Chapter 9, Visiting Friends & Relatives: VFR Travel). Travelers backpacking and camping in rural areas will also have a higher risk of certain diseases than those staying in luxury, air-conditioned hotels.