Rationale:

• Probabilities of specific disease are affected by geographic area visited, type of travel, time of travel, type of food and water ingested, and vaccination history.
• Yellow fever is not prevalent in Asia or India.
• Adventure travelers to the Rift Valley are more likely to acquire schistosomiasis or leptospirosis from fresh water contact than are visitors to Nairobi, Kenya.
• Dengue is less likely to be acquired during the dry season, when mosquito transmission is markedly reduced.
• Enteric fever relatively unlikely in persons eating only cooked food and bottled water.
• The efficacy of yellow fever, hepatitis A and B vaccines makes these diseases unlikely if patient is vaccinated.

Evidence:

• Consensus.

Comments:

• Rapid diagnostic tests for several diseases are often limited or not available.
• Malaria should always lead the list in the differential diagnoses of fever in travelers or immigrants who have been in an endemic area within the previous 3 months. Although these persons often present with common ailments, physicians must be alert to recognize and treat malaria to avoid a tragic outcome.
• Like malaria, several diseases are unlikely to be considered by physicians not well-acquainted with tropical diseases; are seen with appreciable frequency among U.S. travelers returning from malarious areas; can present clinically within 2 months of exposure; and may be serious or life-threatening if not treated with specific antibiotic drugs.
• Definitive diagnoses often rely on nonroutine methods of pathogen isolation or serologic testing that relies on serologic comparisons of acute and convalescent (2 to 4 weeks later) antibody titers. For example, the diagnosis of dengue virus infection in the U.S. requires that acute and convalescent serum samples be sent through state health departments to the CDC's Dengue Branch.