Evaluation of two ELISA Assay Kits against RT-PCR for diagnosis of Dengue Virus Infection in a Hospital Setting in Karachi, Pakistan

Objective: To evaluate two commercially available ELISA-based kits against RT-PCR for the diagnosis of dengue virus infection in a Tertiary Care center in Karachi. Methods: During the 2006 Dengue outbreak, sera were collected from patients clinically classified as dengue fever and graded according to WHO grading. Out of these, 83 samples were selected randomly and analyzed using two different commercial kits (PanBio versus Calbiotech) and were compared with RT-PCR. Clinical charts of the inpatients were also reviewed. Statistical significance was considered at P ≤ 0.05. Results: Clinically, a total of 29 (69%) in-patients were diagnosed with dengue haemorrhagic fever, the remaining 13 (30.9%) were diagnosed as dengue fever. Diagnostic PCR was positive in 73 (87.9%) of the total 83 patients. PanBio capture ELISA had a sensitivity of 83.5%. Calbiotech on the other hand, had a sensitivity of 50.7%. The association of PanBio assay with PCR was found to be statistically significant (p<0.001). Conclusion: Although RT-PCR is considered as gold standard for diagnosis of dengue virus infection, serological methods play important role in diagnosis as they are cost effective and easily available, especially in dengue endemic countries. Sensitivity and specificity of commercial kits can be variable; therefore evaluation of commercial ELISA kits is important in local setting.