General Approach to the Returned Traveler
The Post-Travel Evaluation
Travel-related health problems have been reported in as many as 22%–64% of travelers to developing countries. Although most of these illnesses are mild, up to 8% of travelers are ill enough to seek care from a health care provider. Most post-travel infections become apparent soon after travel, but incubation periods vary, and some syndromes can present months to years after initial infection. When evaluating a patient with a probable travel-related illness, the clinician should consider the items summarized in Box 5-1.
Box 5-1. Important elements of a medical history in an ill returned traveler
- Severity of illness
- Travel itinerary and duration of travel
- Timing of onset of illness in relation to international travel
- Past medical history and medications
- History of a pretravel consultation
- Travel immunizations
- Adherence to malaria chemoprophylaxis
- Individual exposures
- Type of accommodations
- Insect precautions taken (such as repellent, bed nets)
- Source of drinking water
- Ingestion of raw meat or seafood or unpasteurized dairy products
- Insect or arthropod bites
- Freshwater exposure (such as swimming, rafting)
- Animal bites and scratches
- Body fluid exposure (such as tattoos, sexual activity)
- Medical care while overseas (such as injections, transfusions)
The Severity of Illness
The severity of illness is not only important in order to triage the patient but also can distinguish certain infections from each other. Is this a potentially life-threatening infection, such as malaria? A severe respiratory syndrome or signs of hemorrhagic fever are examples of cases that 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 a distinct pattern of diagnoses depending on the region of the world visited. In travelers to sub-Saharan Africa presenting with fever, malaria was the most common specific diagnosis. On the other hand, febrile patients after travel to Latin America or Southeast Asia were much more likely to have dengue. 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.
Timing of Illness in Relation to Travel
Most ill travelers will seek medical attention within 1 month of return from their destination, because most common travel-related infections have short incubation periods. Occasionally, however, infections such as schistosomiasis, leishmaniasis, or tuberculosis can manifest months or even years later. Therefore, in unusual cases, a detailed history that extends beyond a few months before presentation can be helpful. The most common travel-related infections with short incubation periods are listed in Table 5-1.
|Systemic febrile illness with initial nonspecific symptoms|
|Fever with central nervous system involvement|
|Fever with respiratory symptoms|
|Fever and skin rash|
Underlying Medical Illness
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).
Vaccines Received and Prophylaxis Used
The history of vaccinations and malaria chemoprophylaxis should be reviewed when evaluating an ill returned traveler. Less 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 chemoprophylaxis 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 found in a large 2010 GeoSentinel study of returned travelers included enteric fever (typhoid and paratyphoid), viral hepatitis, and influenza. More than half of these patients with vaccine-preventable diseases were hospitalized.
Individual Exposure History
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 can transmit viruses (such as dengue virus, yellow fever virus, chikungunya virus, and Zika virus) 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.
The activities during a trip and the type of accommodations can also influence the risk for acquiring certain diseases. 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 8, Immigrants Returning Home to Visit Friends & Relatives [VFRs]). Someone backpacking and camping in rural areas will also have a higher risk of certain diseases than those staying in luxury, air-conditioned hotels.
The most common clinical presentations after travel to developing countries include systemic febrile illness, diarrheal illness, and dermatologic conditions. These are described in more detail in the following sections of this chapter (Fever in Returned Travelers, Persistent Travelers’ Diarrhea, and Skin & Soft Tissue Infections in Returned Travelers). Fever in a traveler returning from a malaria-endemic country needs to be evaluated immediately.
Respiratory complaints are frequent among returned travelers and are typically associated with common respiratory viruses (see Chapter 2, Respiratory Infections). Influenza is among the most common vaccine-preventable diseases associated with international travel. Severe respiratory symptoms—especially associated with fever—in a returned traveler should alert the physician to common infectious diseases such as seasonal influenza, bacterial pneumonia, and malaria but could also suggest more unusual entities, such as Legionnaires’ disease. Emerging respiratory infections such as Middle East respiratory syndrome (MERS) and H7N9 avian influenza from China should be in the differential if the travel history is appropriate and respiratory symptoms do not have a clear alternative diagnosis. In these suspected cases, local public health authorities and CDC should be alerted immediately. See relevant sections in Chapter 3 for more information on these emerging infections.
Delayed onset and chronic cough after travel could be tuberculosis, especially in a long-term traveler or health care worker. Other uncommon infections causing respiratory illness after travel to specific regions are histoplasmosis, coccidioidomycosis, Q fever, plague, tularemia, and melioidosis. Helminth infections that produce pulmonary disease include strongyloidiasis, paragonimiasis, and schistosomiasis.
Eosinophilia in a returning traveler suggests a possible helminth infection. Allergic diseases, hematologic disorders, and a few other viral, fungal, and protozoan infections can also cause eosinophilia. Fever and eosinophilia can be present during pulmonary migration of parasites, such as hookworm, Ascaris , and Strongyloides . Acute schistosomiasis, or Katayama syndrome, is also a cause of fever and eosinophilia and can be associated with pulmonary infiltrates. Other parasitic infections associated with eosinophilia include chronic strongyloidiasis, visceral larval migrans, lymphatic filariasis, and acute trichinellosis. Findings in an outbreak of sarcocystosis in travelers returning from Tioman Island, Malaysia, included myalgia and eosinophilia. The affected travelers had eosinophilic myositis on muscle biopsy.
Most post-travel illnesses can be managed on an outpatient basis, but some patients, especially those with systemic febrile illnesses, may need to be hospitalized. Furthermore, potentially severe, transmissible infections such as Ebola or MERS require enhanced infection control measures and may require higher levels of care. Severe presentations, such as acute respiratory distress, mental status change, and hemodynamic instability, require inpatient care. Clinicians should have a low threshold for admitting febrile patients if malaria is suspected. Confirmation of diagnosis can be delayed, and complications can occur rapidly. Management in an inpatient setting is especially important if the patient may not reliably follow up or when no one is at home to assist if symptoms worsen quickly. Consultation with an infectious diseases physician is recommended in severe travel-related infections, when management is complicated, or when the diagnosis remains unclear. A tropical medicine or infectious disease specialist should be involved in cases that require specialized treatment, such as neurocysticercosis, severe malaria, and leishmaniasis, among others. Public health authorities may need to be involved for transmissible, high-consequence infections. CDC provides on-call assistance with the diagnosis and management of parasitic infections at 404-718-4745 for parasitic infections other than malaria or 770-488-7788 (toll-free at 855-856-4713) for malaria, during business hours. After business hours, call the CDC Emergency Operations Center at 770-488-7100.
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Jessica K. Fairley