Study of interleukin-6 and interleukin-8 levels in patients with neurological manifestations of dengue

CONTEXT: Pro-inflammatory markers play a key role in the pathogenesis of various Flavivirus infection. AIM: In this study, we evaluated the role of these markers in neurological manifestations of dengue. SETTINGS AND DESIGNS: Consecutive dengue cases with different neurological manifestations who presented between August 2012 and July 2014 were studied in hospital-based case–control study. MATERIALS AND METHODS: Interleukin (IL-6) and IL-8 level were measured in serum and cerebrospinal fluid (CSF) of dengue cases with different neurological manifestations and also in age- and sex-matched controls. Level was analyzed with various parameters and outcomes. STATISTICAL ANALYSIS: Statistical analysis was done using SPSS version 16.0 by applying appropriate statistical methods. P < 0.05 considered statistically significant. RESULTS: Out of the 40 enrolled cases of dengue with neurological manifestations, 29 had central nervous system and 11 had peripheral nervous system (CNS/PNS) manifestations. In CNS group, both IL-6 and IL-8 (CSF and serum) were significantly elevated (P < 0.001), whereas CSF IL-6 (P = 0.008), serum IL-6 (P = 0.001), and serum IL-8 (P = 0.005) were significantly elevated in PNS group. CSF IL-6, serum IL-6, and IL-8 were significantly elevated in poor outcome patients in CNS group (P < 0.05). CSF IL-6 and IL-8 were significantly elevated in CSF dengue positive cases as compared to CSF negative patients (P < 0.05). Cytokine level was not significantly correlated with neuroimaging abnormality in CNS group. Nine patients died and the remainder recovered. CONCLUSION: Elevated level of IL-6 and IL-8 is associated with different neurological manifestations and poor outcome, but whether they are contributing to neuropathogenesis or simply a correlate of severe disease remains to be determined.