Dengue fever is caused by the Dengue Virus (DENV). It is a single-stranded RNA virus belonging to the Flaviviridae family and the Flavivirus genus. There are four distinct but closely related dengue virus serotypes: DENV-1, DENV-2, DENV-3, and DENV-4. Humans are infected with dengue virus mainly by the bite of an infected female mosquito, mainly Aedes aegypti.