Occurrence of False Positives during Testing for Antibodies to Hepatitis C Virus among Volunteer Blood Donors in India

Abstract

The hepatitis C virus antibody statuses of only 11 (21.5%) of 51 initially reactive samples from volunteer blood donors could be confirmed by using additional screening and confirmatory assays; 23 (45%) were negative by all subsequent assays. Seventeen samples (33.3%) gave variable results in the different assays. The core and NS5 antigens were most immunogenic. An algorithm for serological screening of volunteer blood donors in blood banks of developing countries is suggested.The high rate of chronicity and the debilitating cost of treatment for hepatitis C virus (HCV) infection make the use of highly sensitive immunoassays in blood banks imperative in preventing its transmission. Serological assays designed to detect antibody to HCV (HCV-Ab) are associated with a high degree of false positivity in regions with low prevalence and in low-risk populations such as nonremunerated blood donors (7). The low specificity of these assays results in the loss of apparently infected blood units.Though the phenomenon of the occurrence of false positives during HCV-Ab testing is well known (2), in developing countries like India where only 39% of blood donations are voluntary (5), every effort should be made to prevent false labeling of volunteer blood donors (VBDs). Based on this pilot study, which examined the rate of confirmation of HCV-Ab positivity in a blood bank setting, we propose a simple algorithm for on-site counseling and follow-up for donors in blood banks.Of 14,128 VBDs tested at the Blood Bank at the Christian Medical College in south India between February 1998 and December 1998, 110 (0.77%) tested positive for HCV-Ab. For the purposes of this study, blood samples from VBDs that tested positive were sent for further evaluation to the clinical virology laboratory. Of the 110 serum samples, 51 with adequate volume were used for further testing. The blood bank currently uses Abbott HCV enzyme immunoassay (EIA) 3.0 (Abbott Laboratories, Abbott Park, Ill.). This is a third-generation assay for the qualitative detection of antibodies to the core, NS3, NS4, and NS5 antigens of HCV. Currently, in this blood bank, all units are tested singly and HCV-Ab-positive units are summarily rejected with no further repeat testing. For this study, such HCV-Ab-positive samples were sent to the clinical virology laboratory for further testing. In the laboratory, serum samples were aliquoted and stored at 4°C for testing in a second EIA, UBI HCV EIA 3.0 (United Biomedicals, Inc.), and a microparticle EIA (MEIA), Axsym HCV version 3.0 (Abbott Laboratories). Additional aliquots were stored at Ϫ20°C for immunoblot or line immunoassay (LIA) testing. As samples collected from the blood bank were not appropriate for RNA testing, reverse transcriptase PCR (RT-PCR) testing could not be performed. One of the two kinds of assays, LIA (INNO-LIA HCV Ab III; Innogenetics, Zwijndrecht, Belgium) or immunoblot (HCV BLOT 3.0; Genelabs Diagnostics Pte. Ltd., Singapore), was used as the confirmatory antibody test.All UBI EIAs, Axsym MEIAs, immunoblot...

Intra‐host diversity and evolution of hepatitis C virus endemic to Côte d'Ivoire

“…An independent study conducted in the same locality at about the same time showed an HCV antibody prevalence of 3.3% in women of childbearing age [Combe et al, 2001]. However, the enzyme immunoassay used in the study has been associated with false-positive results [Njouom et al, 2003;Raghuraman et al, 2003]. A more recent report using molecular assays showed the prevalence of HCV infection in Côte d'Ivoire to be 1% [Rouet et al, 2004], which is three times lower than the rate reported here.…”

HBV and HCV prevalence and viraemia in HIV‐positive and HIV‐negative pregnant women in Abidjan, Côte d'Ivoire: The ANRS 1236 study

“…It suggests that: (i) an initial screening with a single G3 EIA is preferable in our setting since the combined use of two first-line EIAs did not allow to identify HCV seroconversion, and all discordant specimens had negative or indeterminate results on supplemental testing; (ii) the choice of a firstline G3 EIA must take into account both its analytical performance (including the definition of a cutoff breakpoint below which a positive result can be generally considered as non-specific) and its cost. Indeed, as indicated in package inserts from manufacturers and as described previously [Tess et al, 2000;Ampofo et al, 2002;Ayele et al, 2002;Njouom et al, 2003], anti-HCV positive specimens with low absorbance values are frequent in tropical areas, possibly reflecting the multiplicity of intercurrent infections occurring in these areas that lead to hyperglobulinemia contributing to false positive results with anti-HCV EIAs [Trepo et al, 1993;Raghuraman et al, 2003]. In our experience, a high frequency of non-specific positive samples was also observed with low positive S/C ratios ( 4) during the primary screening, especially with the Murex assay.…”

Comparison of an Immunochromatographic Rapid Strip Test, ELISA and PCR in the Diagnosis of Hepatitis C in HIV Patients in Hospital Settings in Cameroon

“…This phenomenon further reinforces the importance for investigating further before beginning treatment. False positives with ELISA cannot be completely ruled out in Africa where studies have shown that Africans produce antibodies that react non-specifically with ELISAs and have even prompted the development of newer generations of ELISA [8][9][10]. Figure 3.…”