Dengue Fever is a widespread viral disease carried by the Aedes egyptii mosquito.
This insect "vector" - and efforts to control it - is very important in the spread of this disease. Unlike the Anopheles that spreads malaria, this mosquito reproduces in tiny amounts of water - such as found in an old tin can or tire or roadside ditch, is happy living in urban areas, and bites during the daytime hours. So when Dengue strikes, it tends to strike in epidemic waves.
Areas at risk for Dengue Fever (essentially the entire non-desert tropical region of the earth!):