Chapter 22 

Guide to the Evaluation of Post-Travel Illness

The evaluation of post-travel illness described below is meant to compliment the traveler's medical history and physical examination.

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Review the Itinerary & Associated Disease Risks

Reviewing the travelers' itinerary suggests possible disease risks—and eliminates others. Malaria, for example, may occur in a traveler returned from Africa—but only if the traveler had visited an endemic area.

The Destination Advisor lists the most common diseases endemic in each country. If outbreaks are occurring, that will also be noted (or found on the Travel Health Service link for that country).

>>>Go to the Destination Advisor map and select the countries visited; review the diseases endemic in those countries.

Disease Incubation Period1

Some diseases become symptomatic a few days after exposure; in others, symptoms appear weeks to months later. Knowing the incubation periods of various illnesses can help determine the diagnosis.

How long after return from an endemic area did the traveler become ill?

>>>Go to Incubation Periods for Select Infections with Fever to select illnesses based on their incubation period.

What are the Traveler's Symptoms?

Review the Traveler's Immunization Status

If the traveler has been fully vaccinated against certain diseases they can probably be eliminated from consideration. Not all vaccines, however, are 100% protective. The typhoid vaccine, e.g., provides about 60% protection.

The Post-Travel Medical Checklist

Travel to a particular country doesn’t necessarily mean exposure to a disease endemic in that country; a knowledge of the traveler's activities in that country is essential.

Questions to ask the traveler include the following:
• What countries did you visit and for how long in each?  What specific geographic areas did you visit in each country? Did you visit disease-endemic areas? (For example, in Thailand, malaria occurs only in certain forested border areas, not in the cities.)

• What were your arrival and departure dates? When did you return home?

• When did you get sick? Date you first noted your symptoms?

• What symptom(s) brought you to the doctor?
• Did you receive any vaccinations prior to departure? Have you been previously immunized against diseases such as hepatitis A or typhoid? Are your routine immunizations up-to-date?

• Please list all the vaccines you received during the past 10 years.
• Did you travel in rural areas of tropical/semitropical countries or did you stay exclusively in urban areas and stay in high-end, air-conditioned hotels. Did you stay exclusively in a resort?

• Were you on a cruise ship?

• Were you visiting friends or family?
• Did you take insect-bite prevention measures (e.g., use DEET skin repellents, sleep under a bednet)?
• Did you adhere to your malaria prophylaxis schedule (if prescribed)?
• Did you adhere to safe food and drink guidelines? Did you eat snails, crabs, prawns, raw fish, or inadequately cooked or raw exotic foods made from beef, pork, bear, walrus, or fish? Did you use a water filter or purifier? Drink only bottled water or beverages?
• Did you get sick during your trip? If you were in a group, did others get sick? Did you self-treat for diarrhea or other illness? Did you have an illness with fever while abroad.
• Were you treated in a clinic, a doctor's office, or in your hotel? Were you hospitalized? Where?
• What was your diagnosis, if any? Were any tests done? Were you treated with medications. Which ones? Did you get any shots? Did the medical personnel use sterile equipment?
• Did you receive any intravenous fluids, IV medications or blood transfusions?

What was the exposure of the traveler to the following:
• Unsafe food and drink—Did you eat undercooked or raw meat or fish (e.g., sushi); cold food and salads from buffets or salad bars; street vendor food not well-cooked? Did you drink tap water or untreated water from lakes, streams or ponds? Did you consume unpasteurized dairy products (e.g., raw milk, cheese)? Did you handle freshly slaughtered animals?

• Camping in rural forested or brushy areas; walking/hiking in brushy, forested areas.

• Insect and animals bites—Were you bitten by mosquitoes, flies, or ticks? Were you bitten by a dog or other animal?
• Walking barefoot on beaches or moist soil.
• Freshwater swimming, wading, or bathing. Canoeing or rafting in lakes, rivers or streams.
• Unprotected sex with a new partner. Did you have same-sex contact?
• Recreational drug use (especially by injection), tattooing, body piercing, or surgical procedures.
• People with infectious diseases. Did you work in a hospital or refugee camp? Did you have contact with sick people with respiratory illnesses, such as tuberculosis?

Laboratory Tests & Imaging Studies

Testing may include microscopy, cultures, biochemical tests, including serology, and polymerase chain reaction. The laboratory tests commonly available to evaluate post-travel illness include:
• Complete blood count to screen for anemia, eosinophilia, elevated or decreased  white blood cell count and/or low platelets. Travel-related infections causing eosinophilia are listed here.
• Thick and thin blood films to screen for malaria (3 times over 24 hours)
• Dip stick malaria assay, if available

• Urinalysis and urine culture

• Blood cultures
• Stool culture. Smear for fecal leukocytes

• Cultures of other body fluid/tissues
• Microscopic examination of stool for ova and parasites
• Liver function tests
• HIV test. Suspect HIV when the WBC count is low, especially low total lymphocyte count
• Serology testing (e.g., dengue, brucellosis, leishmaniasis, amebiasis or other parasites, etc.). PCR testing.
• Imaging studies: Chest x-ray, ultrasound, MRI

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