Dengue, or dengue fever, is an epidemic disease in some countries (for example, in Brazil), and its most dangerous form is hemorrhagic dengue. It is caused by four different but related viruses, the reason that it is difficult for an already infected person to become immunized against the disease. Dengue is prevalent in tropical and subtropical regions of Asia, Africa and South America and it is transmitted by the bite of the Aedes aegypti mosquito, a diurnal mosquito.
The viral infection causes varied symptoms similar to flu, like fever, malaise, myalgia (muscle pain); in hemorrhagic dengue high fever, with or without convulsions, and hemorrhages may occur leading to circulatory failure and death. There is no vaccine against dengue since there are four agent viruses and it is supposed that the severity of the disease is greater when the patient is already protected against one type of virus and is infected by another. The best prophylactic method is to eliminate the vector mosquito.