Clinical Findings and Pro-Inflammatory Cytokines in Dengue Patients in Western India: A Facility-Based Study

Background: Descriptions of dengue immunopathogenesis have largely relied on data from South-east Asia and America, while India is poorly represented. This study characterizes dengue cases from Pune, Western India, with respect to clinical profile and pro-inflammatory cytokines. Methodology/Principal Findings: In 2005, 372 clinically suspected dengue cases were tested by MAC-ELISA and RT-PCR for dengue virus (DENV) aetiology. The clinical profile was recorded at the hospital. Circulating levels of IFN-gamma, TNF-alpha, IL-6, and IL-8 were assessed by ELISA and secondary infections were defined by IgM to IgG ratio. Statistical analysis was carried out using the SPSS 11.0 version. Of the 372 individuals, 221 were confirmed to be dengue cases. Three serotypes, DENV-1, 2 and 3 were co-circulating and one case of dual infection was identified. Of 221 cases, 159 presented with Dengue fever (DF) and 62 with Dengue hemorrhagic fever (DHF) of which six had severe DHF and one died of shock. There was a strong association of rash, abdominal pain and conjunctival congestion with DHF. Levels of IFN-gamma were higher in DF whereas IL-6 and IL-8 were higher in DHF cases (p<0.05). The mean levels of the three cytokines were higher in secondary compared to primary infections. Levels of IFN-gamma and IL-8 were higher in early samples collected 2-5 days after onset than late samples collected 6-15 days after onset. IFN-gamma showed significant decreasing time trend (p = 0.005) and IL-8 levels showed increasing trend towards significance in DHF cases (interaction p = 0.059). There was a significant association of IL-8 levels with thrombocytopenia and both IFN-gamma and IL-8 were positively associated with alanine transaminase levels. Conclusions/Significance: Rash, abdominal pain and conjunctival congestion could be prognostic symptoms for DHF. High levels of IL-6 and IL-8 were shown to associate with DHF. The time trend of IFN-gamma and IL-8 levels had greater significance than absolute values in DHF pathogenesis.