A mosquito-borne viral disease occurring in tropical and subtropical areas. Dengue is a mosquito-borne viral infection causing a severe flu-like illness and, sometimes causing a potentially lethal complication called severe dengue. Dengue is a viral infection transmitted by the bite of an infected female Aedes mosquito. Dengue fever is a mosquito-borne tropical disease caused by the dengue virus. Dengue (pronounced DENgee) fever is a painful, debilitating mosquito-borne disease caused by any one of four closely related dengue. What is dengue? Dengue viruses are spread to people through the bite of an infected Aedes species (Ae.