Dengue virus is a member of the Flavivirus genus, which includes yellow fever, Japanese encephalitis, and other arthropod-borne viruses that cause human disease.1 Dengue disease is transmitted to humans by several species of mosquito within the genus Aedes, principally A. aegypti. Dengue disease represents a major and growing medical problem.2 The World Health Organization (WHO) 2009 classification divides dengue fever into two groups: uncomplicated and severe.3 All four serotypes of dengue virus can cause clinical manifestations, ranging from a mild febrile illness to a life-threatening shock syndrome. Infection with one serotype is believed to confer immunity to subsequent infection with the same serotype, but it does not provide durable protection against infection with other serotypes.4 Epidemics of different serotypes can circulate simultaneously and, therefore, an individual can suffer secondary and tertiary dengue infections. More severe disease is thought to be associated with secondary infection with another serotype