Characterization of Immunological Virological and Host Factors in Primary and Secondary Dengue

Abstract

Dengue is hyper endemic in most parts of India, so the risk of severe dengue infection is high in these regions. Dengue was classified based on severity such as dengue without warning signs, dengue with warning signs and severe dengue (WHO, 2009). However, primary and secondary dengue differentiation cannot be done accurately with clinical criteria. Similarly, this differentiation may not be accurately made serologically (NS1, IgM and IgG). Hence it is important to study the virological, immunological and host factors to differentiate primary and secondary dengue. Of the 96 study participants, (91%) had both IgM and IgG antibodies to dengue, in the acute phase of illness. This study classified dengue based on the reference cut off values of and#8805;1.1 (71%) of the study participants were identified as primary infection and (29%) secondary infection. Among the primary dengue, 78% of cases had dengue without warning signs and 22% of cases among the secondary dengue had dengue without warning signs. Among the primary dengue, 63% of cases had dengue with warning signs and 39% of cases among the secondary dengue had dengue without warning signs. Among the primary dengue, 70% had severe dengue cases and among the secondary dengue 30% had severe dengue cases. This study has standardized real time PCR for rapid screening of different dengue serotypes using uni-plex and multiplex methods. All four DENV serotypes are found to be co circulating in Vellore, DENV-1, 2, 3 were identified in the study. DENV-4 was identified from routine diagnostic samples in the laboratory. The genotypic prevalence was also observed and it was found to be similar to other studies in India. The S1P levels were found to be lower in secondary dengue, particularly severe dengue and statistically significant. There was no significant association in the levels of endothelial progenitor cells between dengue patients and healthy controls. There was significant decrease of endothelial progenitor cells in the secondary dengue as compared to primary dengue.