Approach

Classic traveler's diarrhea (TD) is ≥3 unformed stools in 24 hours with at least one of the following symptoms in a traveler visiting a higher-risk destination: nausea, vomiting, cramps, fever, dysentery.

Key risk factors include age <30 years, adventure travel, itineraries with high exposure to food and beverages from unhygienic sources, travelers with prior residence in a higher-risk destination visiting friends and relatives, military personnel deployed to high-risk destinations, and travel during seasons of hot and wet climates.[2][4][9]​​[11][12]​​​[21]​​​​

Traveler's diarrhea diagnosis during travel

Self-diagnosis while still traveling is the usual approach.[1] Travelers should be informed that TD is the sudden onset of abnormally loose or liquid, frequent stools. To tailor appropriate therapy, it is important that the traveler understands how to assess the severity of their illness:[1]

  • Tolerable (mild): not distressing, does not interfere with planned activities

  • Distressing (moderate): interferes with planned activities

  • Incapacitating (severe): completely prevents planned activities.

A subset of patients may develop dysentery (bloody diarrhea) and/or high fever >101°F (38.5°C), which indicates a more invasive, more serious infection. Persistent diarrhea (>14 days' duration) warrants further medical investigation.

Traveler's diarrhea diagnosis post-travel

Returning travelers with diarrhea may warrant stool exam for detection and identification; however, clinical evidence supporting a cost-effective and pragmatic approach is lacking.[1] For acute TD in which appropriate empiric antibiotic therapy has not been tried, therapy should be initiated depending on disease severity.

Microbiologic testing may be considered in the returning traveler with severe or persistent symptoms, and in the returning traveler who continues to be ill despite appropriate empiric therapy for bacterial etiologies.[7][28][29] Diarrheal stool is the preferred specimen over formed stool or swab to detect diarrheal sickness, except in children where swab is acceptable when there is sufficient feces on the swab.[30]​​​​​​

If a decision to test is made, testing strategies may involve multiple methods including culture, immunoassays, microscopy and/or multiplex polymerase chain reaction, due to the myriad of potential etiologies (i.e., bacterial, viral, parasitic).[11][28]​​ Molecular testing using one or more of the multipathogen platforms may be of more clinical utility when rapid results are needed, or when traditional microbiological methods have failed to establish an etiology.

Because of the high sensitivity of molecular diagnostics, it is common to identify multiple pathogens.[4][30]​​ Results will need to be interpreted alongside epidemiologic, clinical, and pre-test history in order to guide reasonable treatment decisions.

Stool cultures usually take a longer time to process and may fail to detect the causative agent.[30]​ Negative stool workups are very likely, and in the acute TD clinical scenario, a course of empiric therapy should be tried. In the case of persistent or chronic diarrhea after travel, the differential diagnosis includes infectious causes (usually protozoal), and postinfectious processes (e.g., secondary lactose intolerance, small intestinal bacterial overgrowth, functional bowel disorder, tropical sprue). Structural organic disease (e.g., celiac disease, inflammatory bowel disease, colon cancer, microscopic colitis) should also be considered, and will require a targeted diagnostic approach for the individual patient.[6][7][29]​​​​​​​

The Infectious Diseases Society of America (IDSA) and the American Society for Microbiology (ASM) guidelines suggest considering testing for parasites in patients having persistent diarrhea for >7 days.[30] Do not order a comprehensive stool ova and parasite microscopic exam on patients presenting with diarrhea of <7 days’ duration who have no immunodeficiency or no history of living in or traveling​ to endemic areas where gastrointestinal parasitic infections are prevalent.[31] This exam often requires submission of multiple stool samples. It is labor intensive, requires expertise to perform, and typically has lower sensitivity when compared to other available tests.[31]​​

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