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ESSENTIALS OF DIAGNOSIS
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ESSENTIALS OF DIAGNOSIS
Most infections are common and self-limited.
Identify patients with transmissible diseases that require isolation.
The incubation period may be helpful in diagnosis.
– Less than 3 weeks following exposure may suggest dengue, leptospirosis, and yellow fever.
– More than 3 weeks suggests typhoid fever, malaria, and tuberculosis.
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GENERAL CONSIDERATIONS
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The differential diagnosis of fever in the returning traveler is broad, ranging from self-limited viral infections to life-threatening illness. The evaluation is best done by identifying whether a particular syndrome is present, then refining the differential diagnosis based on an exposure history. The travel history should include directed questions regarding geography (rural versus urban, specific country and region visited), time of year, animal or arthropod contact, unprotected sexual intercourse, ingestion of untreated water or raw foods, historical or pretravel immunizations, and adherence to malaria prophylaxis.
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The most common infectious causes of fever—excluding simple causes such as upper respiratory infections, bacterial pneumonia and UTIs—in returning travelers are malaria (see Chapter 35), diarrhea (see next section), and dengue (see Chapter 32). Others include mononucleosis (associated with Epstein-Barr virus or cytomegalovirus), respiratory infections, including seasonal influenza, influenza A/H1N1 “swine” influenza, and influenza A/H5N1 or A/H7N9 “avian” influenza (see Chapter 32); leptospirosis (see Chapter 34); typhoid fever (see Chapter 33); and rickettsial infections (see Chapter 32). In recent years, coronaviruses have emerged as particularly significant regional and global outbreaks of various sizes (SARS-CoV, MERS-CoV, and the massive global pandemic from SARS-CoV-2). Foreign travel is increasingly recognized as a risk factor for colonization and disease with resistant pathogens, such as ESBL-producing gram-negative organisms. Systemic febrile illnesses without a diagnosis also occur commonly, particularly in travelers returning from sub-Saharan Africa or Southeast Asia.
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Potential etiologies include dengue, Ebola, Chikungunya, and Zika viruses, viral hemorrhagic fever, leptospirosis, meningococcemia, yellow fever, typhus, Salmonella typhi, and acute HIV infection.
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B. Pulmonary Infiltrates
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Tuberculosis, ascaris, Paragonimus, and Strongyloides can all cause pulmonary infiltrates.
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C. Meningoencephalitis
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Etiologies include N meningitidis, leptospirosis, arboviruses, rabies, and (cerebral) malaria.
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Consider hepatitis A, yellow fever, hemorrhagic fever, leptospirosis, and malaria.
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E. Fever Without Localizing Symptoms or Signs
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Malaria, typhoid fever, acute HIV infection, rickettsial illness, visceral leishmaniasis, trypanosomiasis, and dengue are possible etiologies.
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F. Traveler’s Diarrhea
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Fever and rash in the returning traveler should prompt blood cultures and serologic tests based on the exposure history. The workup of a pulmonary infiltrate should include the placement of a PPD or use of an interferon-gamma release assay, ...