Differential clinical symptoms among acute phase Indian patients revealed significant association with dengue viral load and serum IFN-gamma level

Abstract

Background: During last three decades, dengue (DF), an arthropod-borne viral disease is increasingly prevalent worldwide including India, resulting in serious public health problems.

Objective: This study was carried out during 2012-2013 to evaluate the association of WHO-classified dengue disease symptoms with viral load (VL) and serum IFN-gamma levels in dengue patients from India.

Study design: Blood samples were collected from dengue symptomatic febrile patients (n=127). DEN-VL was determined by quantitative real-time RT-PCR using RNA, extracted from plasma and anti-DENV-IgM was detected by ELISA. Serum IFN-gamma level was detected by ELISA among DENV infected and age-matched control individuals. Association between DEN-VL and IFN-gamma level in patient's sera with WHO-classified disease symptoms was statistically analyzed.

Results: DENV RNA and anti-DENV-IgM was detected among 94% (n=73) and 36% (n=28) of dengue infected patients (n=78) respectively. Fever, nausea, rash, aches & pains, leucopenia and persistent vomiting were significantly correlated with DENV infection (P-value<0.05). Only patients with high-VL exhibited leucopenia, persistent vomiting, abdominal pain and clinical fluid accumulation, which were warning signs of dengue infection according to revised WHO-criteria (P-value<0.05). Clinical symptoms of DENV infected patients, viz. leucopenia, abdominal pain and persistent vomiting were significantly correlated to each other (P-value<0.05). Increased serum IFN-gamma level was detected among dengue patients compared to control individuals. DEN-VL and symptoms like nausea, leucopenia, persistent vomiting and abdominal pain were significantly negatively correlated with serum IFN-gamma level (P-value<0.05).

Conclusion: Serum IFN-gamma level and dengue viremia among acute stage patients might be used as early prognostic marker for disease severity prediction.

Keywords: Anti-DENV-IgM ELISA; Dengue viral load; IFN-gamma ELISA; RT-PCR; WHO classification.