Dengue: The Origins

The Dengue virus (DENV) is a member of the genus Flavivirus of the family Flaviviridae. Dengue viruses are comprised of four distinct serotypes (DENV-1 through DENV-4) each DENV serotype can be divided in different genotypes. Which effectively means that there are 16 different ways of getting infected. Infection with one serotype likely elicits lifelong immunity to that serotype, but generally not against the other three[1].

During the past several decades, dengue viruses have progressively extended their geographic distribution, and are currently some of the most important mosquito-borne viruses associated with human illness[2].

[Picture: www.geog.ucsb.edu]

More detailed phylogenetic studies of the dengue viruses suggest an Asian origin[3]. The most recent common ancestor (MRCA) of all four serotypes of the dengue viruses can now be estimated at 888 AD. There is some tentative epidemiological evidence to support this, with the first reported outbreak of possible dengue-like illness occurring in China in the year 992 AD[4].

The contemporary genetic diversity seen in all four dengue serotypes is related to population growth, urbanization, and mass transport of both virus and its mosquito vector (Aedes aegypti, Aedes albopictus and Aedes polynesiensis).

[1] Midgley et all: An in-depth analysis of original antigenic sin in dengue virus infection in Journal of Virology -2011 
[2] Rico-Hesse: Molecular evolution and distribution of dengue viruses type 1 and 2 in nature in Virology -1990 
[3] Vasilakis et al: Sylvatic dengue viruses share the pathogenic potential of urban/endemic dengue viruses in Journal of Virology - 2010 
[4] Twiddy et all: Inferring the Rate and Time-Scale of Dengue Virus Evolution in Molecular Biology and Evolution - 2003