Dengue virus is a member of the Flaviviridae family, which includes viruses associated with human diseases such as yellow fever, Japanese encephalitis and hepatitis C. Dengue fever is transmitted by mosquitoes, principally Aedes aegypti. There are four serotypes of dengue virus, of which DENV-2 has been the most prevalent in many recent epidemics. Following primary infection, lifelong immunity develops, preventing repeated assault by the same serotype. However, the non-neutralizing antibodies from a previous infection or maternally acquired antibodies are thought to form complexes with a different serotype during a subsequent infection and cause dengue haemorrhagic fever/dengue shock syndrome, which can be fatal. There is no treatment or vaccine available today that can combat this emerging and uncontrolled disease.