SURVEILLANCE: Monitor for symptoms. Realtime PCR assay can be used to quantitatively measure RNA number as an indicator of viral load in infection Footnote 6 . Dengue induced seroconversion can be detected using ELISA Footnote 5 . Detection of circulating secondary antibodies directed against proteins such as NS1, NS2, NS3 and NS5 in patient samples, indicative of prior dengue exposure, can aid in evaluating risk of DHF development Footnote 5 . RT-PCR can be used for direct virus detection Footnote 2 .
It is not clear where the word "dengue" came from. Some people think that it comes from the Swahili phrase Ka-dinga pepo . This phrase talks about the disease being caused by an evil spirit .  The Swahili word dinga is thought to come from the Spanish word dengue , which means "careful." That word may have been used to describe a person having bone pain from dengue fever; that pain would make the person walk carefully.  However, it is also possible that the Spanish word came from the Swahili word, and not the other way around. 
Infection by one of the four dengue virus serotypes has been shown to confer lasting protection against homotypic re-infection, but only transient protection against a secondary heterotypic infection. Moreover, secondary heterotypic infection is associated with an increased risk of severe disease. This and other observations suggest an immunopathological component in dengue pathogenesis, which is referred to as immune enhancement of disease. Due to these dengue-specific complexities, vaccine development focuses on the generation of a tetravalent vaccine aimed at providing long-term protection against all virus serotypes. Additional challenges are posed by the lack of an adequate animal disease model and the resulting uncertainty around correlates of protection. In spite of these challenges, vaccine development has made remarkable progress in recent years, and the current dengue vaccine pipeline is advanced, diverse and overall promising.