Chapter 5Post-Travel Evaluation
Asymptomatic Post-Travel Screening
CDC has no official guidelines or recommendations for screening asymptomatic international travelers, except in special populations such as refugees (see Chapter 9, After Arrival in the United States). Cost-effectiveness studies of routine screening in asymptomatic international travelers have not shown a significant benefit to this approach on a population basis. Therefore, a clinic visit or any nondirected laboratory screening for most travelers is not indicated. Exceptions would be for those with known high-risk exposures that are linked to the transmission of certain agents or for people who have lived abroad.
The decision to screen for particular pathogens will depend on the type of travel, itinerary, and exposure history. Travelers who have engaged in casual unprotected sex or have received an injection, a body piercing, or a tattoo may be screened for HIV, hepatitis B and C, and other potential sexually transmitted diseases (such as gonorrhea) with nucleic acid hybridization tests in urine, and for Chlamydia infections with nucleic acid amplification tests in urine. When travelers with high-risk factors present with a febrile illness, sometimes testing for hepatitis B DNA, hepatitis C RNA viral load, and HIV RNA viral load is recommended, in order to rule out the possibility of acute hepatitis B or C or an acute HIV syndrome.
Eosinophilia in a returned traveler suggests the possibility of a helminth infection, of which the most important is strongyloidiasis. Travelers with eosinophilia who have been exposed to freshwater in areas endemic for schistosomiasis should be screened for this infection. Travelers exposed to soil should be screened for strongyloidiasis and possibly other intestinal parasites. If left untreated, this infection may last for the lifetime of the host, and in an immunocompromised person, it has the potential to disseminate.
Travelers who received blood products in highly endemic areas for American trypanosomiasis (Chagas disease) should be serologically screened for latent Trypanosoma cruzi infection. Asymptomatic international travelers who have been abroad for many months or longer, particularly in developing countries, should be screened for certain diseases by using tests such as hepatitis B serology, HIV serology, syphilis serology, Mantoux intradermal skin test for latent tuberculosis infection (predeparture baseline skin testing should be considered in extended-stay travelers to developing countries or those who will have high-risk exposures), stool examination for ova and parasites, and complete blood count, including a peripheral eosinophil count and red blood cell parameters.
Asymptomatic screening is encouraged in special populations such as refugees and international adoptees. Some of the frequently recommended tests to conduct in these patient groups include the following:
- Hepatitis B serologic panel
- HIV serology
- Syphilis serology
- Complete blood count, including a peripheral eosinophil count and red blood cell parameters
Screening for latent tuberculosis infection can be performed by using one of the following modalities: 1) the Mantoux tuberculin skin test or 2) a blood assay for Mycobacterium tuberculosis infection. Currently, the QuantiFERON-TB Gold In-tube Test is approved for screening adults in the United States. Chest radiograph and sputum studies for mycobacterial staining should be performed for those with positive screening results.
CDC has published guidelines for evaluating refugees for intestinal parasites and tissue-invading parasites during domestic medical evaluations. Screening modalities vary according to predeparture presumptive parasitic therapy:
- Screening for parasitic infection among asymptomatic refugees who had no documented predeparture presumptive antiparasitic therapy should include 2 morning stool samples for ova and parasite examination by the concentration method.
- Screening for parasitic infection among asymptomatic refugees who received single-dose predeparture treatment with albendazole should include the following:
- An eosinophil count should be performed in every refugee.
- Refugees from sub-Saharan Africa with persistent eosinophilia should undergo serologic testing for strongyloidiasis and schistosomiasis.
- Screening for parasitic infections in asymptomatic refugees who received high-dose predeparture albendazole (7-day therapy) or ivermectin, with or without praziquantel, should include a follow-up eosinophil count 3–6 months after completion of antiparasitic treatment. Additional treatment is suggested for those identified with residual eosinophilia at the initial evaluation.
Refugee health guidelines are available on the CDC website (www.cdc.gov/immigrantrefugeehealth/guidelines/refugee-guidelines.html).
- Carroll B, Dow C, Snashall D, Marshall T, Chiodini PL. Post-tropical screening: how useful is it? BMJ. 1993 Aug 28;307(6903):541.
- CDC. Guidelines for evaluation of refugees for intestinal and tissue-invasive parasitic infections during domestic medical examination. Atlanta: CDC; 2010 [cited 2008 Nov 26]. Available from: http://www.cdc.gov/immigrantrefugeehealth/guidelines/domestic/intestinal-parasites-domestic.html.
- Stauffer WM, Kamat D, Walker PF. Screening of international immigrants, refugees, and adoptees. Prim Care. 2002 Dec;29(4):879–905.