31). Similarly, despite an overall increase in the incidence of laboratory-positive cases per 108 US travelers from 53.5 to 121.3 from 1996 to 2005, there was no significant linear trend (p = 0.36) (Figure 2). Dengue virus serotype was successfully identified in 36 (9%) of the 393 acute samples submitted; 5 were positive by RT-PCR, 27 by viral culture, and 4 by both. Of these 36 samples, 10 cases of DENV-1, 11 cases of DENV-2, 7 cases of DENV-3, and 8 cases of DENV-4 were identified.

Just over half (52%) of the 334 laboratory-positive cases were reported from four states: New York, Massachusetts, Texas, and Hawaii (Figure 3). Of all laboratory-positive cases, travel destinations were documented for 240 (72%). The most commonly visited regions were the Caribbean (23%), Mexico and selleck inhibitor Central America find more (20%), and southeast Asia (17%) (Table 1). The most commonly visited destinations within each region were Puerto Rico (n = 25), Mexico (n = 36), and Thailand (n = 20), respectively. The

median age of all laboratory-positive cases was 37 years (range: <1 to 75 y); 166 (50%) were male. Among the 334 laboratory-positive patients, 30 (9%) had primary infections and 55 (16%) had secondary infections. The most commonly reported symptoms were fever (55%), headache (35%), myalgia (30%), and rash (28%). Other reported symptoms included chills (26%), nausea or vomiting (17%), arthralgia Branched chain aminotransferase (14%), diarrhea (14%), and retro-orbital pain (10%). Some travelers had severe illness: 41 (12%) were hospitalized, 41 (12%) had at least one hemorrhagic manifestation (most common: petechiae, n = 25), 31 (9%) had platelet counts ≤100,000/mm3, and 4 (1%) had evidence of capillary leakage. Of the laboratory-positive

cases, 119 (36%) met WHO criteria for DF, 2 (1%) met criteria for DHF, and none met criteria for DSS. Two (1%) fatal cases occurred in previously healthy young adults who had traveled to Mexico and acquired secondary dengue infections. This review of 10 years of dengue surveillance data among travelers from the 50 US states and the District of Columbia provides an important measure of the frequency and severity of travel-associated dengue illness. An average of 120 suspected travel-associated dengue infections were reported annually to the PDSS, and there was no significant increase in the incidence of laboratory-positive cases in travelers. Most reported infections were mild; relatively few cases were hospitalized. However, the data underscore the risk of dengue infection for travelers to dengue-endemic areas. Although 12% of laboratory-positive dengue cases were hospitalized, cases of severe dengue illness were uncommon among US travelers. Over the 10-year analysis period, few cases were reported as having hemorrhagic manifestations, and even fewer met WHO criteria for DHF. These findings are consistent with previous research on travel-associated dengue.