Low Specificity of the Third Generation Elisa for HCV Detection in Voluntary Blood Donors in India

OBJECTIVE: Third generation anti-HCV ELISA is currently recommended for the diagnosis of HCV infection. We determined its specificity in voluntary blood donors (VBDs) and patients with chronic liver disease (CLD) in relation to confirmatory line immunoassay (LIA) and reverse transcription polymerase chain reaction (RT-PCR). MATERIAL AND METHODS: 1926 serum samples of VBDs and 16 HCV related CLD patients were screened by ELISA. An optical density/cut-off ratio (OCR) of >1 was taken as positive for anti-HCV antibodies. Samples were confirmed by LIA and HCV-RNA detection by RT-PCR. Interpretation of LIA was done as: indeterminate, reactive or non-reactive. Every 50th VBD sample, negative for anti-HCV by LIA was subjected to LIA and RT-PCR to rule out false negativity of ELISA. RESULTS: Anti-HCV was positive in 34 (1.76%) VBDs and all the CLD patients. Only one (2.9%) VBD was reactive by LIA and 6 (17.6%) were HCV-RNA positive. Serum samples from VBDs with OCR >3 were significantly more often (p<0.05) PCR positive than those with an OCR of >3. In the CLD patients, specimens even with OCR between 1-3 were reactive by PCR. All ELISA negative samples were non-reactive by LIA and PCR. CONCLUSIONS: (i) There is a high false positivity of the third generation ELISA for the diagnosis of HCV infection in VBDs, (ii) Higher OCR should be used for improving the specificity of ELISA in VBDs, (iii) VBDs with an OCR of >3 should be subjected to HCV-RNA determination.