What causes dengue fever and how is it transmitted?
Dengue fever (DF) and dengue hemorrhagic fever (DHF) are caused by dengue viruses (genus Flavivirus; family Flaviviridae). Dengue viruses are small, single-stranded, positive-sense RNA viruses. There are four antigenically-related but distinct serotypes, dengue 1, dengue 2, dengue 3 and dengue 4. Humans manifest dengue fever after being infected by the bite of an Aedes mosquito carrying any one of the serotypes. The primary infection is a severe, usually non-fatal disease. Subsequent infections with a different serotype can be much more serious. Dengue viruses are transmitted in a cycle between humans and mosquitoes. The mosquito species that is most responsible for transmitting the viruses is Aedes aegypti. There is no human to human (or mosquito to mosquito) transmission of the virus.
