Clinical Pearls & Morning Reports
Fever in the returning traveler is a common clinical scenario that often leads to hospitalization and may be the only symptom of a serious or life-threatening illness. A detailed travel history is central to the assessment of the febrile returning traveler. Its value, however, depends on accurate, up-to-date, and rapidly accessible information about the possible infections acquired in the places visited. A new Review Article explains.
Q: What are some resources that are available to assist with the differential diagnosis of fever in a returning traveler?
A: There are a bewildering number of sources of information concerning the geographic risk of various infectious agents. The Centers for Disease Control and Prevention (CDC) website summarizes the global epidemiologic features of the key travel-related infections and provides essential information on the geographic risks of malaria. Collaborative networks of travel clinics have been developed as a powerful surveillance tool; GeoSentinel is the preeminent example. Established in 1995 by the International Society of Travel Medicine and the CDC, GeoSentinel consists of 63 travel clinics on six continents that contribute Web-based, real-time data on ill travelers to a central database. Ongoing trends are tracked on a month-to-month basis for 60 key diagnoses, with additional syndromic surveillance. Quarterly reports are generated centrally for participating sites, and published scientific articles report longer-term trends. Linked surveillance networks exist in Canada (CanTravNet) and Europe (EuroTravNet).
Q: What is the most common life-threatening cause of fever in a returning traveler?
A: In most case series involving fever in returning travelers, deaths have been uncommon, with overall mortality ranging from 0.2 to 0.5%. Falciparum malaria is the most common serious infection seen in returning travelers and remains the main cause of death. Among 82,825 cases of illness in travelers that were reported to GeoSentinel between 1996 and 2011, a total of 3655 cases (4%) involved acute and potentially life-threatening tropical diseases, and fever was a symptom in 91% of these cases. Falciparum malaria accounted for 77% of the 3655 cases, and enteric fever for 18%. Thirteen patients (0.4%) died: 10 with falciparum malaria, 2 with melioidosis, and 1 with severe dengue. Falciparum malaria was acquired mainly in West Africa, and enteric fever was contracted largely on the Indian subcontinent. For the examining clinician, more widely distributed “cosmopolitan” infections that cause severe febrile illness should not be overlooked, including respiratory and urinary tract infections, meningococcal disease, and tuberculosis. Even among travelers returning from the tropics, “nontropical” causes of fever are common, with a rate of 34% reported in one European case series.
A: Novel surveillance methods provide a valuable additional source of information. Automated news-scanning software can enable early detection of outbreaks. For example, HealthMap successfully tracked the 2009 H1N1 global influenza outbreak using multilingual data from news wires, media websites, RSS (Really Simple Syndication) feeds, mailing lists such as ProMED, and authoritative sources such as the World Health Organization (WHO), the CDC, and the European Centre for Disease Prevention and Control.
A: KABISA, developed by the Institute of Tropical Medicine of Antwerp, Belgium, is another clinical decision-making support system that is available free of charge for the diagnosis of febrile illnesses after tropical travel. In a study involving 205 patients, KABISA performed as well as expert travel physicians in diagnosing febrile illnesses, often providing unconsidered diagnoses. The Global Infectious Diseases and Epidemiology Network (GIDEON) offers a commercial computer software program that uses a Bayesian matrix to generate a differential diagnosis on the basis of a patient’s travel history, the clinical and laboratory findings, and the incubation periods for possible infections. Independent evaluations of the program’s performance suggest that it provides a reasonably accurate differential diagnosis that may alert inexperienced physicians, in particular, to unconsidered infections.