Fever in a Returned Traveler: An “Off the Cuff” Diagnosis

Figure 1. Islands of normal skin surrounded by blanching erythema on the abdomen of a 21-year-old woman who returned from travel in Sri Lanka. Diagnosis: Dengue fever. The most commonly diagnosed tropical infections that cause fever in the returned traveler are malaria, dengue, typhoid, and viral hepatitis [1]. The epidemiology may change with appropriate pretravel vaccination and use of malaria prophylaxis. Dengue fever was diagnosed in our patient because serological testing of an acute-phase serum specimen demonstrated a strongly positive IgM titer of 21.33 (normal, !0.90). The combination of fever, myalgias, retro-orbital pain, and erythroderma with thrombocytopenia and leukopenia in a person returning from an area where dengue is endemic suggests a diagnosis of dengue fever. A " tourniquet sign " (i.e., petechiae originating at sites of pressure, reflecting endotheliitis) may be observed during physical examination (figures 1 and 2). Dengue fever is the most common arboviral illness, and, in 2002, the World Health Organization estimated that there were 50 million infections with dengue virus, 500,000 cases of dengue hem-orrhagic fever, and 15,000 deaths secondary to dengue infection per year [2]. The infection is transmitted most commonly through a human-mosquito-human cycle involving the mosquito Aedes aegypti. The incubation period of dengue virus is generally 4–7 days. The short incubation period is an important epidemiological clue. The diagnosis is confirmed by serological test results, and it is defined by a 4-fold increase in acute-and convalescent-phase IgG titers or detection of a specific IgM response [3]. Dengue hemorrhagic syndrome (DHS) is marked by plasma leakage (hemoconcentration and serous effusions), thrombocytopenia, and bleeding [4]. The risk for DHS increases with subsequent exposure to different serotypes of den-gue virus, which has implications for persons with a history of dengue fever who travel to regions where dengue is endemic. Despite our patient's petechiae and positive tourniquet test result, she did not meet the criteria for DHS, given her lack of increased vascular permeability. A. aegypti is often found in urban settings, so, in contrast to malaria, dengue is still a risk for people traveling only to urban areas. The most important measure for prevention of dengue infection is avoidance of the vector A. aegypti, a mos