Investigating the 2005 Singaporean Dengue Outbreak

Abstract

Patienta??s clinical and immunological data were collected during the 2005 Singaporean dengue outbreak. The study aimed at distinguishing dengue fever from other febrile illnesses. It identified low white blood cell counts along with lower number of lymphocytes as clinical indicators and lower serum levels of IL-2, decreased levels of TNF-I?, but increased IP-10 and IL-10 levels as immunological markers for the early stage of dengue infection.We also aimed at accurately predicting disease severity in adult infections. Classification of severe patients based on low platelet counts identified viral load, secondary infection, IP-10, IL-8 and IL-10 as possible severity markers for dengue pathogenesis in an early stage of disease.Phylogenetic analysis of 54 DENV-1 and 40 DENV-3 full length genomes revealed high levels of similarity between strains within a serotype. Serotype 3 viruses persisted by silent maintenance since 2003 before the large 2005 Singaporean dengue outbreak. Investigations of identified clades within the two serotypes did not result in severity related genomic differences but detected IFN-I?, IL-8 and viral load as serotype specifics related to disease severity. Serotype 1 was more likely to cause severe disease than serotype 3.