Dengue fever is a benign, acute febrile syndrome occurring in tropical regions. Nausea, vomiting, and loss of appetite are common Dengue fever symptoms. Dengue fever is caused by one of four different but related viruses; it is spread by the bite of mosquitoes, most commonly the mosquito Aedes aegypti, which is found in tropical and subtropical regions. Infection with Dengue viruses produces a spectrum of clinical illness ranging from a nonspecific viral syndrome to severe and fatal hemorrhagic disease. The disease is characterized by sudden onset of fever (at or over 38°C during the first 3 to 5 days), headache, general malaise, bone and muscular pain, vomiting or diarrhea, a generalized rash and in some persons, hemorrhagic manifestations that are usually mild. Some patients may develop low platelets, low blood pressure and severe bleeding requiring hospital care (Dengue hemorrhagic fever). Dengue hemorrhagic fever usually results from a second infection from a different Dengue virus. The cause of death from Dengue hemorrhagic fever is dehydration from loss of plasma volume, not the hemorrhage itself. The risk of dying with adequate treatment is less than 1%, regardless of age group.