RESUMO
The introduction of DENV-3 genotype III in Latin American countries has been associated with dengueoutbreaks, and the role of the virus with respect to the occurrence of dengue haemorrhagic fever (DHF)has been different depending on the country. We have conducted research on the relative abundance of DENV-3 in relation to the incidence of DHF in a Colombian endemic area. Additionally, it wasexplored using phylogenetic analyses whether or not viruses are genetically distinct in relation to the severity of dengue. Viral isolation was made from serum samples collected during the period fromJanuary 2007 to October 2008. Sequences from the envelope gene of viruses from Colombia andLatin American countries isolated from DF and DHF patients and submitted to GenBank were compared. We found that in 2007–2008 the predominance of DENV-3 declined as compared to 2002–2004(28.3% versus 87.8%), whereas the DENV-1 and DENV-2 predominance increased (54.7% versus2.7% and 16.9% versus 5.4%, respectively). This relative abundance of serotypes coincided with an increase of DHF compared with the period of the highest DENV-3 dominance (25.9% versus 4.6%).Phylogenetic analyses showed that: (i) there is no relationship between DENV-3 clades and the severity of the disease; and (ii) Colombian viruses clustered apart from those coming from countries where DENV-3 has caused severe dengue. The results suggest that DENV-3 could not play any important rolein the occurrence of DHF in Colombia, and that local viruses are genetically distinct from LatinAmerican viruses associated with epidemics of DHF.