1. 
   

   What infections should be considered?

   
   
2. 
   

   What questions should be asked in the travel history?

   
   
3. 
   

   What diagnostic tests should be conducted?

   
   
4. 
   

   Which patients should be hospitalized?

   
   
5. 
   

   What clinical factors put patients at risk for serious complications?

   
   
6. 
   

   When should an infectious disease physician be consulted?

International travelers are commonly plagued by medical problems, particularly after travel to a resource-poor setting. About 8% of travelers to developing countries seek medical care while they are away or after they return. Although fever in the traveler may be caused by mild illnesses, it may also be a harbinger of potentially lethal infection. The evaluation of the febrile traveler is complicated by the wide array of possible etiologies. It is critical to consider which infections are endemic to the area visited, potential exposures, the time between exposure and the onset of symptoms, and associated clinical findings. This chapter reviews the common causes of fever in returning travelers and the appropriate initial diagnostic evaluation.

GeoSentinel, a worldwide network of travel and tropical medicine clinics, provides the largest database for travel-related infections. From 1996 to 2004, the five most common diagnoses for patients with systemic febrile illnesses presenting to GeoSentinel clinics from the developing world were malaria, dengue, mononucleosis due to Epstein-Barr virus or cytomegalovirus, rickettsial infection, and typhoid fever.

In the GeoSentinel database, malaria was the predominant cause of systemic febrile illnesses overall, and it was one of the three top causes from each of the six regions of the developing world. Malaria was the leading cause of systemic febrile illness in travelers returning from Sub-Saharan Africa and Central America. In the United States, more than 50% of cases of imported malaria occurred among immigrant families who had made recent visits to their country of origin. Dengue was the second most likely cause of systemic febrile illnesses overall and the leading cause for fever in travelers to Southeast and South Central Asia, the Caribbean, and South America. Rickettsial infections were an important cause of fever in travelers to Sub-Saharan Africa, and they were often infected with Rickettsia africae (African tick-bite fever). Typhoid fever was especially common in travelers to South Central Asia, but it also occurred in travelers to other regions.

In a later GeoSentinel study of returning travelers with fever, 35% presented with a systemic febrile illness, 15% with acute diarrheal disease, and 14% with respiratory symptoms. Among those with systemic febrile illnesses, 59% were diagnosed with malaria, 18% with dengue, 6% with typhoid or paratyphoid fever, and 5% with rickettsial illness. Additional causes of febrile syndromes included mononucleosis syndromes (Epstein-Barr virus, cytomegalovirus, acute HIV infection, or toxoplasmosis), leptospirosis, amebic liver abscess, viral meningitis, and relapsing fever.

Among patients with fever and diarrhea, the most common diagnoses were traveler’s diarrhea, Campylobacter, nontyphoidal Salmonella species, and shigellosis. In those with fever and respiratory symptoms, nearly half were diagnosed with bronchitis or an acute unspecified respiratory infection. Other common diagnoses were bacterial pneumonia, tonsillitis, influenza or an influenza-like illness, and sinusitis.

It is critical to identify all regions that the traveler has visited in the past year, including layovers or short stops. The Centers for Disease Control and Prevention (CDC) Web site (www.cdc.gov) has a travel site that lists common infections by each country and region, as well as reports on disease outbreaks. The World Health Organization Web site (www.who.int) also has information about disease outbreaks. It is particularly important to identify regions of travel where malaria and dengue are endemic.

It is also necessary to define the dates of travel and the timing of symptom onset, which may permit the estimation of the approximate incubation period. Table 190-1 lists the incubation periods for several bacteria, viruses, fungi, and parasites that cause fever in returning travelers. Some infections can be excluded based on an incubation period that is inconsistent with the timing of fever. For example, a traveler presenting with a systemic febrile infection three weeks after returning would be very unlikely to have dengue, which nearly always presents within 14 days. The duration of the trip can also be helpful. Malaria is more often reported in long-term (> 6 months) than short-term travelers, though 5% of patients with malaria in the GeoSentinel database had traveled for less than one week. Some infections are seasonal, but some seasonal infections (such as influenza) may present at unusual times given that peak seasons may differ in tropical climes.