Dengue hemorrhagic fever in an adult traveler returning to Japan.

We report the case of a Japanese traveler who developed dengue hemorrhagic fever (DHF) with a probable secondary infection with dengue virus type 2 (DENV-2). DHF usually occurs in children, and rarely in adult travelers. Proper and timely interventions can markedly reduce the mortality rate of DHF patients. The expansion of endemic areas and increased frequency of travel to these areas may suggest increased incidence of DHF in non-endemic areas in the near future. Early recognition of reinfection with dengue virus and warning signs of circulatory failure are crucial to prevent a severe shock state.