As the popularity of international travel, especially to exotic locations, continues to rise, physicians are increasingly encountering febrile patients who have recently visited tropical countries. It has been estimated that 1 5% to 37% of short-term travelers experience a health problem during international travel, and a febrile illness has been reported to occur in up to 11% of returned travelers. There are many possible causes of fever in this population, and the clinician must search for clues during the evaluation to help make the correct diagnosis. In the majority of cases, the cause of the fever is a common illness such as a tracheobronchitis, pneumonia, or urinary tract infection. However, fever in the returned traveler should always raise suspicion of a severe or potentially life-threatening tropical infection. Malaria, in particular, must be considered if there was travel within an endemic area.

The majority of travelers with fever have infections that are common in non-travelers, such as upper respiratory tract infections, urinary tract infections, and community-acquired pneumonias. Once routine infections have been considered, the differential diagnosis should be expanded to include travel-related infections. Malaria is the most important cause of fever in a returned traveler from the tropics. Plasmodium falciparum malaria can be rapidly fatal but is curable with appropriate therapy, so this must be a key diagnostic consideration in such patients. Other important causes of fever in returned travelers include typhoidal and non-typhoidal salmonellosis, dengue fever, viral hepatitis, and rickettsial infections. In rare instances, noninfectious diseases such as malignancies or collagen vascular diseases may appear coincidentally during travel and should be considered in the differential diagnosis.